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Stena Teknik - Design A Ship's Hull Form with Minimum Resistance

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Thanks for looking into our challenge! STENA is always looking for ways to be more environmentally conscious, and one way to do that is to reduce emissions.

The challenge here is to be more sustainable by designing a ship’s hull form to be less resistant in the water, and thus reducing our consumption of energy and reducing our emissions to the atmosphere.

The goal of this challenge is to design a hull form with 16,000 tons of displacement.
What would be the hull design with the least resistance through the water?

Requirements

  • JUDGING CRITERIA

    1. Resistance through water
    2. Novelty of design
    3. Quality of calculations

  • SUBMISSION FILE FORMATS

    IGES Format
    Rendering files
    Speed - Resistance calculations & results
    Hull surface roughness assumption

  • TECHNICAL REQUIREMENTS

    Design speed 20 knots
    6.5 meter draft (harbour restrictions)
    Length over beam ration less than 8 (L / B < 8)
    Bare hull only - to be considered
    No propulsor/propeller to be included
    Surface ship (not submarine)
    16,000 tons of displacement

Rules

  • ENTERING THE COMPETITION

    The Challenge is open to everyone except employees and families of GrabCAD and the Sponsor. Multiple entries are welcome. Team entries are welcome.

    By entering the Challenge you:
    1. Accept the official GrabCAD Challenges Terms & Conditions.
    2. Agree to be bound by the decisions of the judges (Jury).
    3. Warrant that you are eligible to participate.
    4. Warrant that the submission is your original work.
    5. Warrant, to the best of your knowledge, your work is not, and has not been in production or otherwise previously published or exhibited.
    6. Warrant neither the work nor its use infringes the intellectual property rights (whether a patent, utility model, functional design right, aesthetic design right, trademark, copyright or any other intellectual property right) of any other person.
    7. Warrant participation shall not constitute employment, assignment or offer of employment or assignment.
    8. Are not entitled to any compensation or reimbursement for any costs.
    9. Agree the Sponsor and GrabCAD have the right to promote all entries.

    If you think an entry may infringe on existing copyrighted materials, please email challenges@grabcad.com.

  • SUBMITTING AN ENTRY

    Only entries uploaded to GrabCAD through the "Submit entry" button on this Challenge page will be considered an entry. Only public entries are eligible. We encourage teams to use GrabCAD Workbench for developing their entries. Entries are automatically given the tag "shiphullchallenge" when uploading to GrabCAD. Please do not edit or delete this tag. Only entries with valid tag will participate in the Challenge.

  • AWARDING THE WINNERS

    The sum of the Awards is the total gross amount of the reward. The awarded participant is solely liable for the payment of all taxes, duties and other similar measures if imposed on the reward pursuant to the legislation of the country of his/her residence, domicile, citizenship, workplace, or any other criterion of similar nature. Only 1 award per person. Prizes may not be transferred or exchanged. All winners will be contacted by the GrabCAD staff to get their contact information and any other information needed to get the prize to them. Payment of cash awards is made through PayPal. All team awards will be transferred to the member who entered the Challenge.

  • We will release the finalists before the announcement of the winners to give the Community an opportunity to share their favorites in the comments, discuss concerns, and allow time for any testing or analysis by the Jury. The Jury will take the feedback into consideration when picking the winners.

  • Winning designs will be chosen based on the Rules and Requirements.

  • This Challenge ends on February 25th, 2019 (17:00 EST.) Finalists will be announced March 4th, 2019, and winners will be announced March 11th, 2019.

Prizes

$15,000 in Prizes!

1st Place:

$7500

2nd Place:

$5000

3rd Place:

$2500

About the jury?

Stena Teknik

About Stena

Stena believes that sustainable business is long-term business and is based on the group’s common values. The three main areas within the Stena Sphere are shipping, ferry operations, and offshore drilling. We offer first class transport and logistics for our customer’s needs. Our Ropax and Roro vessels are an important part of Europe’s trade, while our fleet of tankers carries oil, gasoline, gas and vegetable oils all over the World.
Stena has 21 ferry routes with some 35 vessels in Northern Europe and Stena Shipping operates some 100 tankers.

Stena Teknik is a common resource for all maritime-related business in the Stena Sphere and has the role of an expert function primarily in marine technology. Stena Teknik conducts cutting-edge research to meet future challenges and to increase competitiveness.

324 comments

  • Larry V

    Larry V 8 months ago

    Can we submit a design with no calculations? :)

    Larry V has uploaded 124 CAD models & has left 33 comments.
  • Winston Jennings

    Winston Jennings 8 months ago

    Are there any particular threshold values we should aim for?

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Patrick Kittler

    Patrick Kittler 8 months ago

    Sometimes organic/intuitive skills of genius level in design occur in folks who may not have access to the fluid dynamics software. I do not have this skill, but the sponsor of the competition should accept designs without full calculations which they can process if they spot obvious skill. A tiny tiny investment if they ever actually use the design. A great initiative. Thanks

    Patrick Kittler has uploaded 0 CAD models & has left 1 comments.
  • Kesa

    Kesa 8 months ago

    Larry V the calculations are required for your submission. If you send in a model without it, the model most likely will not be considered.

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Ármin Fendrik

    Ármin Fendrik 8 months ago

    Is the 6.5m draft maximum, minimum, or exact?

    Ármin Fendrik has uploaded 55 CAD models & has left 106 comments.
  • Marco QM

    Marco QM 8 months ago

    Are there any specific measures to be considered? (width, length, how deep it's supposed to go...)
    Also, to those who do not have access to fluid dynamics software, I recommend Autodesk Flow Design, it's free and easy o use; will not give you any specifics as its not designed for boats but with the Cd and watching the airflow you'll get a good idea.

    Marco QM has uploaded 0 CAD models & has left 4 comments.
  • Nicolas Marc

    Nicolas Marc 8 months ago

    - 16,000 tons is the total in charge?
    - Single hull or multi hull?
    - 16,000 tonnes, this represents about a boat about 150 metres long and more, but it will depend on its use; perhaps we have to respect the specific dimensions of certain types of equipment?
    - What type of transport?
    - Bow bulb studied and classified for use in ice?
    - Are you looking for a hull for a multi-purpose vessel?
    - Use for ocean travel only? with occasional coastal traffic?

    Nicolas Marc has uploaded 65 CAD models & has left 956 comments.
  • Per Wimby

    Per Wimby 8 months ago

    6,5m max draft, single hull, RoRo cargo, no ice requirement and short international voyage.

    Per Wimby has uploaded 0 CAD models & has left 2 comments.
  • dima78

    dima78 8 months ago

    Создайте подводное крыло с возможностью прилипания (подхода) к килю судна при прохождении мелководных ( по осадке) русел для подхода к портам.

    dima78 has uploaded 11 CAD models & has left 22 comments.
  • Roger-Marie Couture

    Roger-Marie Couture 8 months ago

    I can not wait to see that.

    Roger-Marie Couture has uploaded 140 CAD models & has left 744 comments.
  • Ananth Narayan

    Ananth Narayan 8 months ago

    "The goal of this challenge is to design a hull form with 16,000 tons of displacement". I don't understand with term 16,000 tons displacement. Please clear my doubt anyone.

    Ananth Narayan has uploaded 62 CAD models & has left 235 comments.
  • Sava Savov

    Sava Savov 8 months ago

    @Ananth That means that the mass of the ship is 16 000 tons when the ship is fully loaded and its underwater volume will be about 16000 m^3. With other words: 16 000 m^3 of water (which is 16000 tons water) are replaced with 16000 m^3 underwater volume of the ship and the mass of all ship (not just the underwater part) is 16000 tons too.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Don Blankenship

    Don Blankenship 8 months ago

    maybe they are looking for new or another employee.... hmm? why not test the international waters for new talent?

    Don Blankenship has uploaded 0 CAD models & has left 1 comments.
  • j t

    j t 8 months ago

    Maybe they are looking for new calculation methods, besides it's not that hard to do some calculations.
    Either-way i'll wait a while before i submit my entries.

    j t has uploaded 8 CAD models & has left 5 comments.
  • Marco QM

    Marco QM 8 months ago

    Probably just looking for ideas for the hull, to get a basic shape and then get a well-paid team to fully develop it...

    Marco QM has uploaded 0 CAD models & has left 4 comments.
  • Husein

    Husein 8 months ago

    @Per Wimby Can you give us some rough dimensions of the hull instead draft and beam ratios. We are not all ship architects :)

    Husein has uploaded 18 CAD models & has left 24 comments.
  • Sumit Goski

    Sumit Goski 8 months ago

    What is the light weight of the ship ?

    Sumit Goski has uploaded 0 CAD models & has left 3 comments.
  • Jamie

    Jamie 8 months ago

    clarification - is the over displacement weight inclusive of the vessel displacement??

    Jamie has uploaded 1 CAD models & has left 14 comments.
  • Melville

    Melville 8 months ago

    Can we design the ship for North-Atlantic Harsh wave patterns ?

    Melville has uploaded 14 CAD models & has left 6 comments.
  • Melville

    Melville 8 months ago

    In any case the stiffness has to be optimized near mid stern portion to suit harsh wave patterns ? What about introduction of metal formed creases in this area

    Melville has uploaded 14 CAD models & has left 6 comments.
  • Sava Savov

    Sava Savov 8 months ago

    @Jamie The easiest way to find out what's going on is: Imagine a picture - we have only water. Everything is in balance. Then imagine that you see a ship that floats in the water. Again everything is in balance. What do we find? We find that some water that was on the first picture is missing, and in its place there is the underwater part of the ship. So, we can conclude that the ship has replaced the missing water by volume - with its underwater part and that the ship has replaced the missing water by weight - with its own weight.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Per Wimby

    Per Wimby 8 months ago

    North Atlantic is not an option; short international voyages, Total displacement (including deadweight and lightship) about 16.000 tonnes. Max LOA 200m

    Per Wimby has uploaded 0 CAD models & has left 2 comments.
  • Husein

    Husein 8 months ago

    Is the 6.5 meter draft (harbour restrictions) the vertical distance between the waterline and the bottom of the hull?

    Husein has uploaded 18 CAD models & has left 24 comments.
  • Guillaume Florent

    Guillaume Florent 8 months ago

    This is a question to Per Wimby, who is on the jury of this challenge and kindly added some comments to this page.
    Mr Wimby, I see some extra requirements in this comments thread from you: 200 LOA max, short voyages, single hull, RoRo.
    I guess these requirements from a jury member are 'officially' added to the technical requirements in the challenge presentation at the top of this page? 200 LOA max and single hull are pretty clear requirements/constraints. Yet, how would the fact that it is a RoRo for short trips translate into more measurable requirements in the context of resistance minimization?
    All the best.

    Guillaume Florent has uploaded 2 CAD models & has left 1 comments.
  • Nick Tracy

    Nick Tracy 8 months ago

    Ship Hull design has already pretty much hit a pinnacle when it comes to mono hull designs and cargo ships. You should try some other energy saving methods like optimizing the bulbous bow for the speeds and tonnage of the ship. Use air lubrication under the hull. Use a Hi-Fin on the prop. Use a hybrid system for power. Make use rotor sails... The list is extensive on new technology, The hull should be a multi hull for the absolute best design for energy conservation. Smaller footprint in the water and the least displacement means less drag coefficient.

    Nick Tracy has uploaded 0 CAD models & has left 8 comments.
  • walid youcef errahmani

    walid youcef errahmani 8 months ago

    Dear juror's
    This what we need,some challenges like this,its a good chance
    and opportunity for us to learn others stuff in this field,and discover our skills.
    Just a note,it was be great if you could add some specify value for the resistance,power,ship service,that can help us to work with a real criteria.
    thanks again

    walid youcef errahmani has uploaded 4 CAD models & has left 18 comments.
  • Adem Y

    Adem Y 8 months ago

    @Per Wimby, Requirements are clear, but you wrote a comment max loa 200m? Is it a another Requirements or not? if yes you have to publish it on main Requirements. do I check comments regularly what if you wrote something?

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Dario D'Amico

    Dario D'Amico 8 months ago

    I would kindly ask to extend the deadline by a week or so, the calculations are taking more than expected, I'm not sure whether or not I'll be ready by the 8th.

    Dario D'Amico has uploaded 11 CAD models & has left 19 comments.
  • Winston Jennings

    Winston Jennings 8 months ago

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Ashish Verma

    Ashish Verma 8 months ago

    Same here as @Dario D'Amico

    Ashish Verma has uploaded 30 CAD models & has left 16 comments.
  • Winston Jennings

    Winston Jennings 8 months ago

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Kesa

    Kesa 8 months ago

    Hello GrabCAD Community,
    Stena the sponsors of this Challenge have requested that we extend this Challenge to the 25th! So you have even more time to create high quality models and renders. Good luck to all participants.

    Best,
    Kesa
    GrabCAD Community Manager

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Pedro Henrique

    Pedro Henrique 8 months ago

    Kesa, would know when Finalists and winners will be announced?

    Pedro Henrique has uploaded 1 CAD models & has left 5 comments.
  • Laszlo Doro

    Laszlo Doro 8 months ago

    Great! I have just came to notice that this is going on.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Germano Pecoraro

    Germano Pecoraro 8 months ago

    Dears Stena Line Company,
    I am a little worried about some projects presented in the last days.
    Some projects besides the study of the hull, have also uploaded an idea of bodywork of the superstructures.
    I wonder: is not that then who presented only the hull analysis then will be penalized in the final competition?
    In other words "you did not draw the deckhouse, so you're out"!
    What should be done!?

    Best Regards
    Germano Pecoraro - Italy

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • Syamsiprop

    Syamsiprop 7 months ago

    is deadline extended?

    Syamsiprop has uploaded 76 CAD models & has left 13 comments.
  • Matt Firmani

    Matt Firmani 7 months ago

    Hey everyone! Stena Teknik has asked us to extend the challenge until February 25th, so we will be accepting new submissions until that time. It also gives everyone who has already submitted a design the chance to review their work. If you have any questions, just let us know!

    Matt Firmani has uploaded 2 CAD models & has left 38 comments.
  • Wellington Pires

    Wellington Pires 7 months ago

    Dear Stena Line team,
    All submissions will be evaluated together, as soon as the deadline is over, or the team is already fully checking the submissions already uploaded?
    Regards,
    Wellington

    Wellington Pires has uploaded 0 CAD models & has left 2 comments.
  • Vladimir Izmailov

    Vladimir Izmailov 7 months ago

    serious body design calculations cost a lot more than a prize, only two free offers (everyone knows): hydrofoil or air bubbles at the body

    Vladimir Izmailov has uploaded 55 CAD models & has left 27 comments.
  • Pedro Henrique

    Pedro Henrique 7 months ago

    Dear Stena Line team,
    As was not stated if the submissions will be evaluated together when the deadline is over, or when they are submited. I am kindly asking to have my team model revisited.
    Dominant RoRo - Stena Teknik Ship Hull Challenge
    Regards,

    Pedro Henrique has uploaded 1 CAD models & has left 5 comments.
  • Germano Pecoraro

    Germano Pecoraro 7 months ago

    Excuse me, Who is the Hull Winner?

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • Trent Pierce

    Trent Pierce 7 months ago

    Who is the 10th finalist? I only see 9 finalists on the results page.

    Trent Pierce has uploaded 1 CAD models & has left 9 comments.
  • Adem Y

    Adem Y 7 months ago

    I can't believe last 12, some design's unrealistic to building.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 7 months ago

    Not trying to stir anything up, but I am genuinely curious to what criteria these final 12 were picked. I looked through almost all of the entries and saw some really good analysis done with iterative designs that weren't picked, etc. It is why I spent so much time on this (and got a really pissed off girlfriend in the end). Was it just judged off of purely minimum resistance? A lot of these free hull shape calculators had very odd and low numbers and don't analyize the shape like CFD does.

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Since there are probably 3 winners already selected. The rest is just "stuffing". For example: Make It Real: The winners of the challenge are meaningless. It's not accidental ...

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Varga Norbert

    Varga Norbert 7 months ago

    Good luck to the all finalists ! :)

    Varga Norbert has uploaded 8 CAD models & has left 14 comments.
  • K'Tan

    K'Tan 7 months ago

    If the jury considered the resistance through the water of these 12 finalists, then the L009 would have a minimum (with a very large margin from the others). Although such a boat hull is unreal...
    In all other cases, this is just a new design. But, I congratulate all the finalists :)

    K'Tan has uploaded 0 CAD models & has left 1 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Really??? even not in 12??? Noooo )))))

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Sava Savov

    Sava Savov 7 months ago

    I am in! Yea! But I bet for STENA RO-RO by milan.kalajdzic-1 - I liked it immediately - just looks good and very clear

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Sava Savov

    Sava Savov 7 months ago

    Of course I wish luck to my friend Clix

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • farrux s

    farrux s 7 months ago

    Animation of my latest failure))
    https://m.youtube.com/watch?v=mN0oJNRrcLA

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    very good farrux s

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    I definitely have to agree with Adem Y and Jonathan Ziegler.
    With all the respect, some of the selected designs are very hard to imagine as a RoRo carrier or even as any kind of ship. For example, I mean some of them lacking buoyancy in the bow or aft or both, has boxy appendages or irrational stern...

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Adem Y

    Adem Y 7 months ago

    I agree with you Laszlo and Jonathan, how the jury shows other Stena chairmans to show we selected last 12 design in 120. Its like a joke. Respect all competitors but as a naval architect half of the designs are not even concept design. How the jury made a resistance test? I can't believe

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    Congrats! I tested many uploaded models and I hope jury tested them either, while the resistance of my model is lower than 10/12.

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Luis, I also used Numeca, and since I'm quite new to this software, I just stick to the wizard. You can see the results. I even run for 16 to 22 knots, in 2 knots steps. And that was all full separate calculation, not prediction.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Adem Y

    Adem Y 7 months ago

    Luis, It doesn't matter how many models people have, multiple entries are welcome and yes not validated cfd"s are just colored fluid Dynamics you know that. And why just holtrop, fung is also good for that ship range and speed. And definitely cfd results are different empirical formulas, we can manipulate easily maxsurf and others even they cant solve flaps, wedges,or duck bottoms.. therr are good designs but we're not happy to some selected ones.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Adem Y

    Adem Y 7 months ago

    I agree you too Luis but I dont believe all the ships has enough faired surface to consider building. It's not a nasa clamp challenge, we must design something looks like ship not 10 times scaled sailing boat if we're designing roro. If Per Wimby didn't write 200m max a loa designs would be different, because its a naval architecture question type some missing requirements, we should find what actually looking for after regressions :) anyway good luck to everyone it was good i read a lot of academic articles about roros and learned something.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    The challenge title is "design a ship's hull"... and then the requirements, and roro carrier.
    Or we could go just with something resembling a Sears–Haack body, cut in half and extrude above...

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Crazy selection of finalists. Some of them are perfect, but some it's hard to believe to be selected by professionals.... Shame...

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Some which is even hardly questionable for a decent cfd run. I mean how could you consider a wake, if the hull is an open shell (towards the stern)?
    (maybe I should cool down a bit, but there are so many questions...)

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    I hope, Stena's representative will be so kind to explaine something. Othervise this situation makes an idiots of large part of participants )). Stena Lines - is famous Swedish company, big name. Definitely, their high-level specialists will clarify the situation and rules at least now. So, let's wait, I'm sure Stena's representatives respects this society and will give explanation regarding rules ASAP.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Francisco Inglés

    Francisco Inglés 7 months ago

    I love the smell of BARRACUDA in the morning ;-) congrats to all finalists!

    Francisco Inglés has uploaded 1 CAD models & has left 8 comments.
  • Francisco Inglés

    Francisco Inglés 7 months ago

    Keep Calm and Let's BARRACUDA !!

    Francisco Inglés has uploaded 1 CAD models & has left 8 comments.
  • Germano Pecoraro

    Germano Pecoraro 7 months ago

    I am agree with Laszlo Doro.
    I have serious doubts that some of the selected hulls are able to operate in a difficult context such as that of the North Sea.
    Some have poor transverse buoyancy or lack the bow bulb.
    They were selected hulls with <600 KN of friction?
    Some hulls of mine have lower resistance than 600 KN!

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • Germano Pecoraro

    Germano Pecoraro 7 months ago

    Then also keep in mind that the lines of the displacing hulls cannot be modified too much.
    Several researches are aimed at reducing the resistance by placing an air cushion in a kind of rails between the hull and the water.
    From an energy point of view it would not cost too much, because it involves blowing exhaust gases under the hull (blowing, not compressing like a hovercraft).

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    Thanks Luis

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Adem Y

    Adem Y 7 months ago

    Luis ı hope jury read all comments.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Jesús Miguel Pérez Martín

    Jesús Miguel Pérez Martín 7 months ago

    This kind of comments do not contribute to longer publishing challenges by any other company. I think these challenges are perfect for people who wants to know which enterprises are searching for talent. It is a good place to proove your skills and show your capabilities compiting with people from all over the world. I will keep on participating in these challenges and I hope that Grabcad keeps doing a great job.

    Jesús Miguel Pérez Martín has uploaded 1 CAD models & has left 2 comments.
  • farrux s

    farrux s 7 months ago

    I took part in many engineering competitions and usually judges never clarify why they think my entry was not good enough. So I'm not expecting any comments here explaining the true logic behind the selection process.
    I'm only interested in one thing - what do you guys think about my work. I spent almost 2 weeks and performed maybe over 50 CFD simulations. I learned a lot during the process as I'm not from this field of engineering.
    I know there are also naval architects and other experienced engineers competing here, but nobody wrote a more or less detailed review about my entry. Maybe i tried to reinvent the bicycle, maybe there are some stupid mistakes but anyway I would be grateful to read your reviews and criticism. Just for myself. Thanks! :)

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 7 months ago

    Farrux, as a fellow engineer I feel you were one of the best entries into this competition. Your analysis was very thorough and you had a very innovative design. I agree that it is unlikely that the judges will give you any feedback but you definitely deserve the kudos!

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Most of these are completely irrational for any kind of ship:

    - Several has obvious stability issues, as practically no buoyant force is acting in the bow or stern or both. Such a design could produce nice values in a simulation, but is not suitable for a real ship, as it would very easily pitch, especially when loaded.
    - There is one that straight forward would tip over. By the way that does not even come close to the 16000t of the criteria (14000)
    - toy boat like shape (again, what is with the 16000t criteria?) with a simulation that has nothing to do with boat design.

    I do not want to make this personal, these are just a few examples that makes this selection questionable
    - if we were meant to stick to the defined technical requirements (as many did)
    - and assuming that the design should somewhat resemble something that is suitable as a mean of transportation on water (like not laying on it's side, or act like a seesaw)

    (Or what were these requirements for, and defining roro cargo?)

    Based on the above comments, I think I'm not the only one who is interested in what I was trying to express here.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • farrux s

    farrux s 7 months ago

    Thank you Jonathan! I really appreciate your assessment

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • Adem Y

    Adem Y 7 months ago

    Laszlo Doro %100 I agree with you there no more words. Farrux you made a great job 50 cfd models. Idk did you made a validation or didnt, idea is nice, there are some applications like that, but generally add some foils on bulb, most case in practical they are generating problems on ships, doesnt matter still idea is nice but they actually called energy saving devices, not a ship hull, like others, vedges, propelelr fins, interceptors sternbulb vortex generators, propelelr caps, fins even air lubrication.
    if one of unrealistic shapes who has lower resistance from all is win time to giving up from naval architecture and forget everything we learned.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • farrux s

    farrux s 7 months ago

    Thank you Luis!
    What really surprised me, most of finalists used very old designs, and some are just "industry standard" hull geometries. I couldn't understand what was the design novelty - a second criterion for judgement.

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • farrux s

    farrux s 7 months ago

    Thank you Adem! No unfortunately I didn't have time to validate my simulations.
    I named them as a hull and a damper but I see them as one entity - just a hull, like bulbous bow is not viewed separately from the hull.
    Actually, when I first read the contest requirements I didn't believe that I can create a better design than current hull geometries that are being refined and optimized over centuries. That's why I tried another approach - lowering hull's drag by replacing bulbous bow with another thing)

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • walid youcef errahmani

    walid youcef errahmani 7 months ago

    I guess stena want to make us less efficiency by the finalist results hhhh,anyway I just need to said to the jury's that this is not what we was waiting for,at least you had taken the spending hours in consideration and choose some excellent works to avoid this chaos,but unfortunately here we are

    walid youcef errahmani has uploaded 4 CAD models & has left 18 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    It is quite clear, that real resistance values -or how much the design could be accounted as the hull of a ship- did not take part in the selection process.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Publicity stunt? Here? For a company like stena?
    Highly unlikely. It is too much underground.
    I have a different concept regarding this, but yet I do not want to share.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Manish M C

    Manish M C 7 months ago

    Are we a joke to you did all the calculations manual and submitted ?

    Manish M C has uploaded 11 CAD models & has left 10 comments.
  • Pedro Henrique

    Pedro Henrique 7 months ago

    I can only agree with the critics made above, some of the results for resistance are completely unrealistic for a ship suitable to meet the competition demands.
    My team did not have a specialist in the area, but we're all engineers and we worked hard to research and study naval architecture and engineering, to came up with a design feasible after 21 CFD simulations.
    We're really displeased to see that not only us, but the majority of the entries we deemed as strong contenders didn't make it through.

    Pedro Henrique has uploaded 1 CAD models & has left 5 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Laszlo, I think I know what is in your mind. This grabcad challenges are highly cheating events...

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • farrux s

    farrux s 7 months ago

    I have a question for GRABCAD MANAGERS. Is it usual that challenge results generate so many negative comments or there's really something wrong with this particular competition?

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Previous supercarbody "challenge" was cheating another way - by specification in the rules that despite won your or not, anyway your entry is intellectual property of "sponsor" and grabcad adopt this. By this rule they can assign anybody as winner and want to use any design for free. Here it seems another cheating scheme is in use ))

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    I took my time and had a more close look on these so called finalists and it is kind of a suspicious selection.
    I hate to say this but it very much seems like, these were hand picked to make way for an obvious choice. Unrealistic design had been chosen and some feasible did not get in. If an idea itself was valued, how is it that Farrux's project did not made it to the top 10? Even if it is not suitable for a roro carrier, the idea and the quality of work behind it definitely finalist at least for the selection itself.
    Almost every model that is in this final selection has some obvious fault, like:
    - several which are at least resembling a ship, lacking buoyancy in the bow and aft section, so these would be prone to pitching, especially when loaded
    - not a real ship hull, more like a test piece for experimenting with a code
    - completely standard hull, like if it was taken straight from Delftship database
    - some have poor quality appendages
    - there are which really far from something like a realistic boat.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Here is Stena Teknik webpage: "This server could not prove that it is www.stenateknik.com; its security certificate expired 29 days ago. This may be caused by a misconfiguration or an attacker intercepting your connection." And this is their facebook page: https://www.facebook.com/Stena-Teknik-558488667961736/
    Very similar to this challenge... (

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Adem Y

    Adem Y 7 months ago

    @bogdan, building a ship is a really big thing and we're designed 200m ships and surface qualities of all files are rubbish for shipbuilding industry and and hull surface is %1 of ship there are a lot of works done to do, even I surprised is it hull design challenge? This is a million dollars od job. Anyway challenge is still unfair.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 7 months ago

    Some commentators here seem to have misread the requirements: "The goal of this challenge is to design a hull form with 16,000 tons of displacement.
    What would be the hull design with the least resistance through the water?".

    Nothing said about seakeeping, construction, docking, stability etc.

    Some other commentators have supposed that using conventional regression methods for unconventional shapes is a valid approach... yes they can be easily 30% out. RANS CFD is the tool to be using in 2019, FineMarine, CCM+ or OpenFoam, in sufficiently expert hands. Relative accuracy can be achieved within 1%.

    Almost certainly the lowest five resistances are within the short list, so if some others in the list are much higher resistance than some not in the list, it may be frustrating to some but it should not affect the to three.

    The yellow L009 design actually that has the least resistance of the fleet, being very low in both viscous and pressure drag. It also is the product of a real optimisation process, the only one. It certainly gets my vote. Sure its not practical as it is, but that wasn't a stated requirement.

    What this competition achieves is to show that it is possible to save a huge amount of drag (over 30%) compared to many 'typical' ship shapes, if the usual constraints are set aside. Basically the lowest drag of the short list has 2/3 the drag of the middle of the short list...

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Cad Cam

    Cad Cam 7 months ago

    The comments are correct. They probably chose unrealistic plans ... deliberately!
    There are several unrealistic challenge finalists.

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    YDT, somebody even read additional requirements in the comments:
    1. Per Wimby about 2 months ago
    6,5m max draft, single hull, RoRo cargo, no ice requirement and short international voyage.
    2. North Atlantic is not an option; short international voyages, Total displacement (including deadweight and lightship) about 16.000 tonnes. Max LOA 200m

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Fictitious people will win. And they'll steal ideas. It is possible ??

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Luis Caro
    I also checked. I'm much more interested in what's happening here!

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Adem Y

    Adem Y 7 months ago

    İnteresting, ı just googled stena elektra and this challenge dates are very close.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Yacht Design Technology Ltd:
    The challenge title is "design a ship's hull" not "design a large test piece".
    Anybody could come up with such an obvious shape, but since it was about designing the hull of a ship, for that purpose there are several other features exist that a ship hull should bear.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 7 months ago

    Its not my job to defend Stena/Grabcad but I think 'Ships Hull' as a competition title does not naturally over-ride the actual requirements stated.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Yacht Design Technology Ltd:
    It is not just "ship's hull" -which does not override the requirements- but the also stated "RoRo cargo" definitely asks for ship like properties. Like stability, and so on.
    Luis:
    I think that is impossible, that a company like this would validate test results with a data from a bunch of amateurs. It just does not make sense. They have their resources to experiment, while also most of what is presented here is completely unreliable.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 7 months ago

    Can anyone find a resistance value for finalist Michael Dimou? He has a nice rendering but I can't find anything in the report about resistance.

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • Sava Savov

    Sava Savov 7 months ago

    About this challenge - it seems the best way to find out if some shape is good or not is to make it in real shape and put it in real water. I hope that Stena Teknik will do it at least for the 3 winners or at least for the main winner. And I have this hope just because it will be a great spectacle for all participants.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 7 months ago

    Tank tests are still used to 'confirm' RANS CFD predicted gains, relative to a baseline hull, before expensive ships are built, but CFD at the right level of quality is a mature product these days so it would be exceptional if the gains differed from CFD predicted gains by more than 1%. Such a tank test for a single boat costs much more than the prize pool so not likely that Stena would entertain that idea. Possibly Stena Teknik have in-house CFD and are already ranking some of the finalists.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Luis Caro,
    It is very interesting... We don't know what's going on here. Starting to be a comedy.

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Cad Cam

    Cad Cam 7 months ago

    It would be appropriate for the leaders to respond and look over the finalists.

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Germano Pecoraro

    Germano Pecoraro 7 months ago

    Some of the ship's hull designs were taken by Delft Ship, Free Ship, Orca 3D CFD, etc etc!

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    Exactly Germano! And that effort was enough for being a "finalist".

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Luis Caro,
    I just hope you are not right. If it is, then this is a very unfortunate thing. Gordon Ramsay's kitchen...

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Cad Cam

    Cad Cam 7 months ago

    I'd like to start later in the challenge. I know that I am a person, but when I see them I have become uncertain. This is the second frivolous challenge.

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • Cad Cam

    Cad Cam 7 months ago

    Luis Caro,
    I can see that too... :D

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • farrux s

    farrux s 7 months ago

    after Yacht Design Technology Ltd's kind words about L009 (big yellow hull) i was really interested about this work and checked this model in Fluent. I was expecting from this algorithm generated optimal shape ~1,5 times lower drag than my simple "classical" hull.
    BUT this thing ruined all my expectations by having 13% more drag than my initial model and about 32% more drag than my optimized model.
    maybe I'm doing wrong simulations, or maybe there's something wrong with ANSYS Fluent))) I don't know)

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • Kesa

    Kesa 7 months ago

    Hello GrabCAD Community,
    Just wanted to say Thank you for everyone who participated in this Challenge and congratulations to our finalists.
    We also wanted to Thank Stena for creating and hosting this challenge with us. The Judges will be selecting the Winners in the next couple of days so be sure to keep your eyes open on this challenge.

    Best,

    Kesa
    GrabCAD Community Manager

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 7 months ago

    Farrux, I don't even think it was about lowest resistance. The finalist Michael Dimou does not even have a resistance in his report which is the most important criteria of this challenge. I tried reaching out to GrabCAD about what is happening here, but they have not replied.

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • Kesa

    Kesa 7 months ago

    @Jonathan Who did you reach out to? I haven't received any emails from you.

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 7 months ago

    @Kesa, Matt Firmani. I will send you the message I sent him to keep it offline.

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • Kesa

    Kesa 7 months ago

    @Luis I can see your frustration when it comes to the selection but screaming into the heavens of the comments section isnt going to change the fact that its Stena choice. GrabCAD is a place of creating models and learning new techniques from another and more. If you have an Issue with the challenge or have something that needs to be address take it offline and contact myself or Matt and we will look into it.

    Hope you have a great day,
    Kesa
    GrabCAD Community Manager

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Adem Y

    Adem Y 7 months ago

    Whaaat? Looks like stena want to escape and close it. This isn't announcement that we want? Dont you see Grabcad is there a problem on this challenge? Have you ever seen a such a kind of comment cloud in any challenge and many people says something going wrong?... Ridiculous.

    We take grabcad and stena seriously but I felt they are annoying us. We all know grabcad is in middle between us and them but grabcad need to do a move for community.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Sava Savov

    Sava Savov 7 months ago

    All of us can publish a lot of models for free. And it is understandably that it caress our ego when someone liked them. But when the money comes around, the anti human greedy essence rise up! The sick envy too... this is realy ugly! I hope to we soon overcome the savage instincts, but I'm not optimistic ...

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Kesa

    Kesa 7 months ago

    Stena has issued a statement passed on their finalists selection for this challenge.
    -
    -
    "The selection of the finalists for the GrabCad Challenge was performed in a fair and structured way especially as we didn’t know the identity of the participants.
    All responses were reviewed by a panel including two naval architects who used their extensive knowledge and experience in reviewing the submissions to choose who should be finalists. Every response was reviewed in a similar way."

    Best,
    Alan Gordan

    Kesa has uploaded 1 CAD models & has left 68 comments.
  • Sava Savov

    Sava Savov 7 months ago

    Well Luis, i understand your thoughts but i have nothing to answer - it is Stena turn. I hope they will give respect to "all the people that waste many hours" by answering them why they picked exactly these 13 models. BTW something appeared while writing my answer to you - the post over my post - from Kesa.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Kesa, you, as Grabcad, accepted absolutely not fair rules (requested by supercar system in passed challenge). In accordance to that rules all intellectual rights for all submitted entries are TOTALLY passed to "sponsor". This sows how grabcad respects the community. To kiss "sponsors" in all possible places - this is ok for grabcad, but to protect rights of participants - this is not about you. You tell to Jonathan Ziegler he haven't tried to rich you by mail or somehow else. But I've definitely tried to rich you regarding previous challenge. And do you know? You did't answer. No answer here, no answer by email. What is price for your words?

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    I've checked "Barracuda" by Miguel Cordero. Do you know what? 14 000 m3 of displacement under 7.7 m of draught. 10 300 m3 under 6.5m draught (as requested). It's already not meeting initial conditions. They says they got laminar flow on their hull. HOW they broke law of physic?? It is not possible ))! Most of it, there even no smooth transitions between surfaces under waterline! Even test has been made in limited volume where walls of tank have influence on the test. And somebody says NAVAL architects accept this one??? This is totally idiotic.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Basing on said above, as for my opinion, Stena Teknik is going to pay to their contestant and threw away all strong contestants to make more equal picture to chose their one as winner. I can understand them. Grabcad by their rules and attitude forced to run away from here all more-less professional engineers....

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    I've spent hundred hours for Supercar desidn, hundred hours for this one. For what?? To give away may work for free because of such kind of rules and judgement? All possible hull versions are 1000 times tested and studied. And optimal can't be very different from conventional ones anymore. Why everybody (and Stena etc) researching air lubrication? Because all possible ways to improve hydrodynamic of ship are exhausted 50 years ago. And they says NAVAL architects choosing totally laminar flow hull with 7.7 m of draught or some stupid dolphin nose as winners???? Show me these naval architects!!

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    It's good material to make sentence for some blogs and magazines. Should be very fun. )) I think Grabcad already wants to ban some contestants.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    Thanks Luis. Your work was also very good. But this place is not correct for fair play.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    agree with you Luis

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    Love the song. Frustrated? Little, but now I think I know why my boat is not in the finals. Stena teknik team are eagerly testing it for 2 weeks now ;)

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 7 months ago

    Surface of area of Guillaume Florent's L009 is 4228.3m2, ITTC Cf for 200m ship at 10.29m/s is 0.001408 which makes 323kN your 'Terminal Velocity' for that hull... perhaps someone can correct me. For pure shear drag of that hull FineMarine gave me 339kN. For my hull of 4534m2 that ITTC Cf gives me 346kN while FM gives me 364kN for shear.
    That implies a 'Form Factor' of 1.05 for both shapes, however when comparing to tank derived form factors you have to consider that the CFD pressure already includes the viscous pressure drag.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Husein

    Husein 7 months ago

    These competition here are a yoke. No one needs to meet any criteria and can win ;)
    But I learned something, its a huge waste of time that could be better wasted XD

    Husein has uploaded 18 CAD models & has left 24 comments.
  • Germano Pecoraro

    Germano Pecoraro 7 months ago

    Unfortunately, it became a worldwide malpractice to organize a contest "just to gather ideas and projects", carelessness.
    In this contest the organizers have made some slightness:
    1 - it should have published a precise list with the documents to prepare and publish, nothing more or less;
    2 - they gave us an available performance prediction softwars, VPP, CFD, etc equal for all competitors (of course it would also have needed a kind of basic webinar);
    3 - they should have provided more details about the type of ship to be designed (it is not enough to say a 16,000 ton RO-RO, draft of 6.5 or a length of less than 200 meters, ... ...);
    4 - should have given more importance to the conceptual concept.

    This contest for myself was not a waste of time, because I took the opportunity to keep the combat ready as a naval architect and learn and experiment new ideas.
    And then there was a lack of direct dialogue a Stena Teknik's spokesperson with, whom they could asks questions and comments to.

    However this is the first contest in GradCAD of mine.

    Germano Pecoraro has uploaded 10 CAD models & has left 15 comments.
  • Laszlo Doro

    Laszlo Doro 7 months ago

    "The selection of the finalists for the GrabCad Challenge was performed in a fair and structured way especially as we didn’t know the identity of the participants.
    All responses were reviewed by a panel including two naval architects who used their extensive knowledge and experience in reviewing the submissions to choose who should be finalists. "

    What???
    Some does not even met specified design requirements and resembling more like a soap holder than a boat hull.
    This is ridiculous.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Phillip Shapiro

    Phillip Shapiro 7 months ago

    I agree with most of the posts you need more data LWL draught, stability requirements, curve of areas for loading constraints etc .. Or else a very long rowing skiff shape with elliptical / circular sections will be a great entry off hand. Thanks for the challenge but it's not very serious.

    Phillip Shapiro has uploaded 0 CAD models & has left 1 comments.
  • dejan jayasinghe

    dejan jayasinghe 7 months ago

    exactly, next time I will draw a 200m kayak or america's cup boat from 2000 with quick start module in maxsurf in 15min. Stena should wrote down sinkage allowance in criteria.

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 7 months ago

    At first Stena should not make themselves and us an idiots chosing as finalists entries which are absolutely not fitting requirements and even common sense. It's f*ng shame. And they talk naval architects chose that entries. It is so stupid. When I saw Stena name I thought - this will be professional and fair. But it was the worse challenge ever.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Manish M C

    Manish M C 6 months ago

    i think stena gave its selection criteria to the security in the office that is if below 600 KN of resistance select them and he did the selection . i'm feeling guilty that i gave my 400 dollars worth resistance to stupids like you .

    Manish M C has uploaded 11 CAD models & has left 10 comments.
  • Adem Y

    Adem Y 6 months ago

    Hahaha Luis, absolutely perfect. I also want to face to face that naval architects and stena to tell them fire that 2 naval architect. Are we talking about bottle shape, 16000 dwt kayak? Even tell 5 years of child know how to wrıte roro on google and look images, and guess what child wont see and soap bottle or veri big kayak, 7ne of the gauchely challenge ı have ever joined.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Michael Dimou

    Michael Dimou 6 months ago

    Hey guys, relax. We are here for one purpose, to make a better world. We can not change the results. Please respect each other. It is not make sense this discuss. Focus to your try and not to the result. Obviously, there are guys with less knowledge but with more passion. Please discuss with a purpose to help each other, instead to show the knowledge to each other, the knowledge is free, but the aesthetic and the passion are unique for every person. Cooperation guys, cooperation!!!

    Michael Dimou has uploaded 18 CAD models & has left 33 comments.
  • farrux s

    farrux s 6 months ago

    With a kind help of Mr. Jason (YDTL) i now understand that all my CFD calculations were wrong because of wrong input of unscaled velocity for a sclaed model. That is to say, I used 20 knots velocity with a 1:10 scaled model which turns out to be the same as testing full scale model in 65 knots flow. That's the reason why hull models generated very high waves and this in turn explains why my hydrofoil wave damper worked so well.
    I also want to take back my words about L009, as that CFD had the same scaling flaw.
    I don't regret for all my wasted effort, at least I have learned something new.
    Thank you Stena and GrabCAD for this opportunity.

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • farrux s

    farrux s 6 months ago

    And BIG thanks to Jason)

    farrux s has uploaded 1 CAD models & has left 13 comments.
  • Sava Savov

    Sava Savov 6 months ago

    Why the hell someone will scale his model when it will be tested with computer?

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Sava, The mesh size issue is related to a large ship needing more mesh layers at the wall of the ship in order to achieve an optimum Y+ value for the mesh. (see https://en.wikipedia.org/wiki/Law_of_the_wall) and sometimes also related problems with extreme aspect ratio of the boundary layer mesh, requiring tighter spacing of the mesh in the flow direction.
    That said, its becoming more common to simply use very large Y+ values for full size ships to avoid the mesh size issue and this serves to keep full size problems to a practical mesh size. I haven't fully explored that approach so my tried and tested setup uses model scale results expediency, followed where necessary by full scale runs.
    The scaling of tank model results is a complicated process because you don't exactly know the break down between pressure and viscous forces. Scaling of CFD model results is by contrast very easy as you can scale the exactly known pressure and viscous parts separately. It is also very easy to check the accuracy of such a CFD result scaling because you can also calculate the full size ship when you need to...

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Sava Savov

    Sava Savov 6 months ago

    btw, it seems i have clicked "report spam" to somebody's post - sorry.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Sava Savov

    Sava Savov 6 months ago

    Jason, I promise to try to understand this tomorrow. As you have probably seen, English is not my mothers language :) But I know I can do it. Thanks

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Bogdan, I have assumed that the request to state 'hull roughness assumptions' is so that all entrants can be equalised to the same assumption. For simplicity I chose to use zero roughness, and if Stena choose to compare competitors including 0.000x roughness coefficient they will do so.
    I see no reason that air lubrication is not allowed, and some types can be applied to all the competitors more-or-less equally, others are patented and others, particularly the 'air cushion' type, require a specially designed hull form and a very complicated analysis (probably full scale trials) to prove effectiveness.
    Probably if you have created a hull form for lubrication that does not infringe anyone's patent and you have shown by detailed analysis that it provides less than 400kN, then you should win the competition, (and kick yourself for not keeping it private and patenting it yourself...)

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    I would credit Stena Teknik with the capability of being able to equalise the competitors to the same roughness...

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    @ Yacht Design Technologies ltd. Seems you are professional in this area. I have few questions. Here you says: "Surface of area of Guillaume Florent's L009 is 4228.3m2, ITTC Cf for 200m ship at 10.29m/s is 0.001408 which makes 323kN your 'Terminal Velocity' for that hull... perhaps someone can correct me. For pure shear drag of that hull FineMarine gave me 339kN. For my hull of 4534m2 that ITTC Cf gives me 346kN while FM gives me 364kN for shear". But how you got 0.0014 of Cf. For Fr=0.23 it is 0.00165. 17% more. And 405 kN of Rf instead your 346 as result.... Where you found in challenge conditions air lubrication use is prohibited? Can you show?

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    The Cf is based on the reynolds number, so if the ship is shorter the reynolds number reduces and the ITTC Cf increases. I used 200m length at 10.29m/s. To get 0.00165 your ship would need to be only 55m long.
    As far as I know lubrication is not mentioned so is permitted. My comment in the report was basically saying 'if anyone is saying they've got air injection, sign me up for some of that also..., or I suggest discount it'. Inventing and proving a new lubrication system is, in my opinion, a very big task, for which the first prize would be a very small compensation.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Bogdan,
    reynolds number (Re) for 200m is speed * length * density / dynamic viscosity
    Re = 10.29 * 200 * 1025 / 0.001063
    ITTC 57 Cf = 0.075 / (log10(Re) - 2) ^2

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Sava Savov

    Sava Savov 6 months ago

    I start thinking that it is not a good idea to confine the prizes to only three finalists -why not to 10 or 20? less money will be for the best, but other participants will feel appreciated.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    @Yacht Design Technology Ltd. This what you say in your rapport: "Any of the competing designs can have an air injection or similar system fitted, so unless someone proposes something genuinely new and provides detailed supporting analysis, we feel that it should not be a factor in the competition."... Ok....
    But why you talk the length of your hull is 200m? The length of waterline there is only 188m. And 15 700 disp. on 6.5m draft...
    Yes, I've used a little bit another interpretation of Cf formula. And for my hull I've got 0.0017. Holtrop calculates 594.5 kN for your hull, and Series 60 - 320 kN.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Bogdan, 200m is the dynamic length from the front o the bulb to the transom. It is arguable that for some parts of the boat that is correct but for others its less. For my analysis it is unimportant because I am only using a ratio of the ITTC values to scale the viscous component of my CFD drags from model to full size. Ratio of 20m to 200m gives 0.6311 while ratio of 18.8m to 188m gives 0.62995 so my full size predictions would reduce by 0.2%.
    I guess you may be taking volume as displacement, you need to consider the density of sea water is approx. 1025kg/m3 and multiply your volume by the density to get displacement.
    Holtrop's method is in his own words 'approximate', it is based on statistics. Probably on average it is correct for the top half of the competition fleet, much too low for the bottom half and much too high for the first few boats.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Holtrop method still has its place, some people will continue to use it for early stage concept evaluation, I don't see anyone disputing that. For detailed wave drag comparisons, like ranking the first 12 competitors in a 120 entry competition it is way out of place, I would not expect to see any professionals claiming otherwise and I'm sure the people at Marin would not be using Holtrop method for that purpose.
    Wave drag for the finalists varies by more than 1000%... there is no way for Holtrop method to understand the double bow wave on one of the forms...
    Agree, minimum possible drag for comparison purposes (excluding lubrication) is flat plate + a common roughness coefficient for the purposes of resistance ranking, probably 0.0 or 0.0004

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    When running a static CFD simulation one must carefully monitor the vertical force. This Force must balance the mass force or else you don’t satisfy the citation given in this competition. I think this Is one of the biggest source to error.

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, for high speed planing calculations that are not fully converged or are oscillating a lot I would agree, but for these low Fn calcs they should converge within 0.5% quite quickly. For example https://www.dropbox.com/s/uf08e42sem69jnh/YDTL_Fz.JPG?dl=0 that is newtons for half hull at 0.1 scale.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: I think you are talking about the pressure reflection from the boundary? I am talking about the sum of force in gravity direction = mass x gravity, and that this should be equal.

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, we're talking about the same thing. This is the result for your hull: https://www.dropbox.com/s/ddvv5r4699dccxi/StenaBlue_Fz.JPG?dl=0
    If I take 78280N (by eye) divide by 9.81 to get KG, multiply by two for the other half of the boat, and then multiply by 1000 for the scale factor cubed, I get 15,959,000kg That is 0.25% too light, close enough though.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: And what about you design?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    that was the first link, about 0.1% too light...

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    I've uploaded almost all calculations with formulas on page "3", my Reynold number is 1,526 * 10(9) and my Coefficient of frictional resistance Cf is 0,001453. I got magic number <600KN with Holtrop (592,9KN) and slender body method (551,8KN).

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: You got a really good match, have you tried it in full scale?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, I haven't on this project but have many times before, converging Fz is never a problem for low Froude numbers whatever the scale, but at high Froude numbers it can take a while.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    200m LOA can't be a criteria, people. It has been written by Per in comments. C'mon
    https://www.stenaline.com/ships/stena-superfast-VIII stena ship example: LOA: 203,3m B: 25m Displacement: 30285t not 16000t, ladies and gentlemans. Maybe 200m ship with 16000t displacement would be possible whit carbon-kevlar composites instead of iron. :D

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    dejan, tonnage is not related to displacment, see https://en.wikipedia.org/wiki/Gross_tonnage

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: Yes it is much easier with displacement hull =) I am getting a 7% off in the vertical force, do you use 6.5m as draft in your simulation ?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    YDT Ltd and Louis, I know that. I misread.

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Ok, I can't find displacement values for stena ships, but I want to confirm what I said in my comment above with the following chart: average displacement for various types of ships:
    https://www.researchgate.net/figure/Number-of-passages-and-average-speed-length-and-displacement-per-ship-category_tbl3_324613163
    Passeneger, L 191m, D 23118 t

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, re. 'do you use 6.5m as draft in your simulation ?' I used 6.4 for your hull as a starting point, but the simulations are free in sink and trim.
    https://www.dropbox.com/s/g22tjev99nzh8bj/StenaBlue_Sink%26Trim.JPG?dl=0

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: Nice, what was the final trim and displacement?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond - Trim was -0.0233 degrees, sink was 0.231m at the center of mass.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    (boat was travelling in positive x, y to port, z up.)

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: you are talking about your design now, right?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, I was talking about yours. My design had 0.075 degrees trim, -0.20m sink
    (your ship -0.231m sink)

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: Ok, and COG calculation is based on?

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • Matt Firmani

    Matt Firmani 6 months ago

    Hey everyone! Just a reminder to keep things friendly in chat.
    .
    It's always been implied that our Community Values & Guidelines (https://help.grabcad.com/article/149-community-values-and-guidelines) apply to Challenge pages too. However, from now on, this will be explicitly laid out in the Challenge Rules as follows:
    .
    "Do not be rude to your fellow Community members. This includes insults towards another GrabCAD member for the quality or content of their work. If you have legitimate concerns about the selection process, please report it to us right away, and we’ll pass it on the the judges. But any insulting posts found in the Challenge comments are subject to removal without notice."
    .
    Let's please be respectful, and join together in congratulating our finalists. Stay tuned - our winners will be announced shortly!

    Matt Firmani has uploaded 2 CAD models & has left 38 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Trond, LCG was based on measurement of the volume at 16,000 tonnes, I just used zero for ZCG and YCG.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Trond Svandal

    Trond Svandal 6 months ago

    Yacht Design Technology Ltd: OK =)

    Trond Svandal has uploaded 1 CAD models & has left 9 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Luis, yes, I think it is very difficult to get 16000t with L 200m. Totally Absurd it is and yeah, I am pretty sure you figured it out. Soon!

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Adem Y

    Adem Y 6 months ago

    Matt Firmani if you read all comments from to begining noone said anything wrong each other all we shouting about jury and how they made a selection. I wrote Kesa and nothing changed and stena still didnt made a announcement for us.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    hahaha, smoking rizla +, bravo Luis, you made my day :-)))

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Adem Y

    Adem Y 6 months ago

    Luis that is the point, of course if they say someting not far from your words, but it shows us how grabcad act if something going wrong. as we see they didnt do anything :) event they show comments to stena is enough :)

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Luis, Yes, it looks like shipbuilders don't prefer to share displacement values, I was a cadet on a 148m heavy cargo ship backdays (18000t DISP). Interesting formulas you found, I remeber this one DISPL=LWT+DWT

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    Did anyone else run full scale simulation?
    (It is not completely clear by the above conversation...)

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Manish M C

    Manish M C 6 months ago

    People ! dont worry on your failure, i'm personally a Naval Architect, and many of the other Naval Architects are rejected in this contest. They are Biased based on my perception . If you dint trust my words, i personally make design for people internationally, and after my model didn't get selected i removed all my calculations.Because it is worth much more than this prize. My designs are accepted by classification societies and my designs are alive in Indonesia, United States, Malaysia, Australia and India.As i said dont think you are rejected. Think that these companies are not worth for your designs .Thank you.

    Manish M C has uploaded 11 CAD models & has left 10 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Laszlo, Alexander Mrugowski ran full size Numeca FineMarine calculations. He originally published his CFD result of 292.7 kN for a half-hull (585.4kN for a full hull). I calculated his hull, also with FineMarine at 1/10th scale and for half model got 90.926kN and 318.97kN for pressure and viscous. Scaled to full ship using my ITTC ratio approach you get 2 * (90.926 * 0.631 + 318.97) * 10^3 = 584.39kN
    That was a 0.17% difference.
    Considering the huge spread of drags even within the short list, this shows that scaling subtleties are not so relevant.... as long as the same assumptions of CA are made.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • phickey

    phickey 6 months ago

    Good Day. Wondering when the winners will be announced?

    phickey has uploaded 2 CAD models & has left 9 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    Are you ready to be winner? ))

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    it seems like finalists are frustrated too :-)))

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Good day everyone. From past experience, the results are just what I expected, nothing new. I agree with everyone's comments about this competition and I also share your frustration. That being said, I would kindly ask for some feedback on my entry HAT Concept. I'm curious to see if it's possible.

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Sava Savov

    Sava Savov 6 months ago

    Winston, I can’t say anything valuable about the design and the hydrofoils because I am far from ship expert, but I saw that you made your calculations with DELFTship. And you got 164 kN for resistance force which is too low to be truth. I made similar mistake using DELFTship to find the resistance for my boat - I got very nice low resistance force, but after that I saw that the draft was set to 1 meter for the calculations although the design draft was 6,5 meters.
    Here Stene Teknik Recent Development Ship Hull Design
    I post a picture, in the comments, where to check if your draft is set properly.

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Thank you Sava for your response. I wasn't sure about the calculations because in my case it is more complex and I have no such experience. My main concern was the concept itself. Can any expert please weight in your comments, I would really appreciate it and we can all learn something. Thank you for sharing.

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    I'm sorry to say Winston, but for a displacement hull this is just not the way to go.
    Unfortunately this is just a method for creating unnecessary drag.

    (also I'm not a qualified naval engineer myself, maybe someone will be so kind explain it more precisely, but nevertheless that is the matter.)

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Thank you Laszlo. They actually use hydrofoils on cruise ships on a smaller scale for stability. It produces enough force to be effective. I believe with careful engineering, it can work for this application as well.

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    Dynamic stabilizers are also increasing drag, but there the gain is stability. You want to reduce drag by lifting the hull, but seems like you do not take into account the relatively large surfaces of the added appendages. There is also energy lost where it goes for lifting the hull and also what is needed to push the increased cross section in the water. And even though if you could generate considerable lifting forces it is still a large displacement hull, and reducing the waterline -which seems to be one of your goals- means reducing the theoretical hull speed also.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    I hear what your saying, but by that logic, airplanes, helicopters should not fly either. Only testing can prove or disprove my concept. But I assume you agree it's possible.

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Hi Winston, the benefit of your wings would be in reducing wave drag, but the cost in friction and induced drag would be much higher. A modern 787 aircraft has a lift to drag ratio of about 21, but a smooth RORO shape can be closer to an L/D of 400 because a 200m long ship is so efficient at carrying weight.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Thank you everyone for the insights. I really appreciate it. But how much different is hydrodynamics from aerodynamics. It may be difficult to see but lets say compare the hydrofoils on a submarine, they're small but effective and in proportion, very little induces drag to the vessel.

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Yacht Design Technology Ltd

    Yacht Design Technology Ltd 6 months ago

    Hi Winston, fins on a submarine are there for dynamic stability and control, at the cost of drag. The Submarine is usually neutrally buoyant. Aerodynamics and Hydrodynamics are both 'fluid dynamics', essentially the differences are the density and viscosity of the fluid.
    As regards your specific solution, hydrofoils are beneficial for much higher Froude numbers, for example a small powerboat at high speed could have an L/D nearer to 6 than 400, so hydrofoils are then very beneficial.

    Yacht Design Technology Ltd has uploaded 2 CAD models & has left 24 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    If I knew what I was doing, I'm sure I can make it work, just play around with shapes and different physics principles and effects, i.e (Conanda effect, Magnus effect, Bernoulli principle, etc). We are all engineers here and I'm sure if this was actually the challenge, everyone would have a solution. Thank you again everyone for the discussion while we wait on the results!

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    "That's the spirit, George..."
    ;)

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Guess we all knew what we signed up for...

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    (sorry, Luis I just deleted it, did not see your answer)
    So: It became quite void for the final, that is for sure.

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • Adem Y

    Adem Y 6 months ago

    Whats happening here :D

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Laszlo Doro

    Laszlo Doro 6 months ago

    fckd up LVL9000
    :D
    (I feel sorry for you Louis, of course.)

    Laszlo Doro has uploaded 7 CAD models & has left 38 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    I just can't believe it Luis, what the hack. Anyway, here is a link of what can go wrong on the ro-ro ships from yesterday. https://gcaptain.com/burning-conro-grande-america-sinks-in-bay-of-biscay/

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    So, is this radio silence?

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    Grabcad banned Luis... It's going lower and lower..

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Andreas Morch Hildershavn

    Andreas Morch Hildershavn 6 months ago

    The winner was supposed to be announced on the 11th. What's up with the delay? Must be difficult to select a winner.

    Andreas Morch Hildershavn has uploaded 0 CAD models & has left 2 comments.
  • Adem Y

    Adem Y 6 months ago

    Must be hard selecting winners in 200m bottles and kayaks 😅

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Sava Savov

    Sava Savov 6 months ago

    If I had some experience before this challenge I could make my bottle with even smaller resistance. I experimented a little with Maxsurf – it is not difficult to make a boat with the requirements of this challenge. I made a new “boattle“ in 10 min by using a yacht from Quick Start. I first deleted all but the main surface. Than with a little scaling I came close to the desired dimensions. But the displacement was small. I healed this by decreasing the surface stiffness. And after several relocations of some points, I got a hull with the following results for resistance:
    Holtrop – 568,5 kN
    Fung – 597,2 kN
    Slender Body – 574,2 kN

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Cad Cam

    Cad Cam 6 months ago

    This is a fallen challenge. I'm sorry. :)

    Cad Cam has uploaded 1 CAD models & has left 26 comments.
  • phickey

    phickey 6 months ago

    Good day Matt. Any idea when the winners will be announced?

    phickey has uploaded 2 CAD models & has left 9 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Sava, like I said in comment up above 10min is enough.

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • KUKI PEREZ

    KUKI PEREZ 6 months ago

    hi boys, I follow this challenge since the beginning, I haven´t participated cos' I'm not an expert in ships, but after read comments, it made history in Grabcad, and not for good of the community and the website ;-) I think that in future, could be good change somethings, if not, the people run away from this site and it's a pitty. BTW congrats to the winners when it happens bye! xoxo!

    KUKI PEREZ has uploaded 0 CAD models & has left 3 comments.
  • Sava Savov

    Sava Savov 6 months ago

    Dejan, yes, but you know what? It is very easy and faster to use Quick Start to make a cargo hull too – without any graphical changes I adjust 16032 t displacement, 6,5 m draft – just with scaling the Quick Start hull.
    And the results (without touching the model!) for resistance are:
    Holtrop – 641 kN
    Fung – 748 kN
    Slender body - 899,3 kN

    Sava Savov has uploaded 17 CAD models & has left 47 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    @ Kuki, Grabcad is degradating... Administration here is very strange guys. No feedback. It's useful to perform challenges tasks for yourself. But stupid to publish them here... After 2 last challenges reputation of local challenges got -100 points.

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Bogdan, exactly. These challenges offers us a way to make better products and then patent and develop it yourself. Not because they didn't acknowledge it doesn't mean its not good. I find I make good solutions to their problems thanks to these challenges and only publish them for my portfolio. Perhaps in the future I will keep the ideas to myself and earn more than the change offered here. Here's my key example WJDAE - Click Lock Revolution

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Sava, of course, I know that, I use maxsurf for a long time now, but I prefer modelling in Rhinoceros and then testing it with maxsurf modules.

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Adem Y

    Adem Y 6 months ago

    I guess they're waiting 1april :)

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Matt Firmani

    Matt Firmani 6 months ago

    Hey everyone! My sincerest apologies for the delay. Unexpected circumstances have arisen, and we are waiting on the Stena judges to choose our three winners. We will announce them here as soon as we are notified. Thanks for your patience!

    Matt Firmani has uploaded 2 CAD models & has left 38 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    Simple, rock, paper, scissors!

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    They waiting when attention to this "challenge" faded and then to cheat ))

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • phickey

    phickey 6 months ago

    Matt. Do you know how much longer before the winners are announced?

    phickey has uploaded 2 CAD models & has left 9 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    You are winner, don't worry )

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Adem Y

    Adem Y 6 months ago

    Poor grabcad, worst challenge ever made. :)

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Matt Firmani

    Matt Firmani 6 months ago

    Hey everyone!

    My sincerest apologies for the delay. The winners of the STENA Design Challenge have been announced, and we'd love it if you could help congratulate Sava Savov, Guillaume Florent and Yacht Design Technology Ltd or their had work and dedication in this challenge.

    We are aware that things got a little bumpy this time, so we thank each and every one of you for your patience and understanding. We would also like to thank STENA for sponsoring this challenge.

    We hope to see you all for our next challenge. Stay tuned!

    Matt Firmani has uploaded 2 CAD models & has left 38 comments.
  • Adem Y

    Adem Y 6 months ago

    Absolutely shame challenge for naval architecture. Bye grabcad and ı hope stena teknik tried to buıild that hulls of tjey have enough face.

    Adem Y has uploaded 1 CAD models & has left 18 comments.
  • Michael Dimou

    Michael Dimou 6 months ago

    Bravo guys!!!!

    Michael Dimou has uploaded 18 CAD models & has left 33 comments.
  • phickey

    phickey 6 months ago

    Congrats to the winners.

    phickey has uploaded 2 CAD models & has left 9 comments.
  • phickey

    phickey 6 months ago

    Matt - I don't think I'll be doing any of these challenges in the future.

    phickey has uploaded 2 CAD models & has left 9 comments.
  • KUKI PEREZ

    KUKI PEREZ 6 months ago

    oh my gosh, we have winners!!! congrats to the kayaks boys ;-)

    KUKI PEREZ has uploaded 0 CAD models & has left 3 comments.
  • Jonathan Ziegler

    Jonathan Ziegler 6 months ago

    This has been by far the most confusing contest I have ever been in. Congrats to the winners, I hope you get paid.

    Jonathan Ziegler has uploaded 4 CAD models & has left 8 comments.
  • dejan jayasinghe

    dejan jayasinghe 6 months ago

    Congrats winners!

    dejan jayasinghe has uploaded 1 CAD models & has left 22 comments.
  • Bogdan Tovstonog

    Bogdan Tovstonog 6 months ago

    I hope Stena will really build their Electra on the winning hulls ))

    Bogdan Tovstonog has uploaded 9 CAD models & has left 59 comments.
  • Winston Jennings

    Winston Jennings 6 months ago

    That's the goal of the challenge. It will be exciting to see these new hull forms sailing the seas in the coming years 😌

    Winston Jennings has uploaded 275 CAD models & has left 879 comments.
  • Clix

    Clix 6 months ago

    Congrats to the Winners!, Thank you Stena for the opportunity !

    Clix has uploaded 13 CAD models & has left 265 comments.
  • abu adil khan

    abu adil khan 6 months ago

    how to know about the winner ?

    abu adil khan has uploaded 5 CAD models & has left 7 comments.
  • phickey

    phickey 5 months ago

    Good Morning All. I received an email from Stena asking if I could send them my model and info. Did anyone else receive a similar email from Stena?

    phickey has uploaded 2 CAD models & has left 9 comments.
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