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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?
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
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.
$15,000 in Prizes!
$7500
$5000
$2500
Stena Teknik
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.
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585bf3f5
Jacob Norrby
0ec86086Have an awesome idea for this competition? Want to win cool prizes? Sign-up now to upload your entries.
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229 comments
UniqueCAD almost 7 years ago
Can we submit a design with no calculations? :)
Winston Jennings almost 7 years ago
Are there any particular threshold values we should aim for?
Patrick Kittler almost 7 years 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
Kesa almost 7 years 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.
Ármin Fendrik almost 7 years ago
Is the 6.5m draft maximum, minimum, or exact?
Marco QM almost 7 years 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.
Nicolas Marc almost 7 years 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?
dima78 almost 7 years ago
Создайте подводное крыло с возможностью прилипания (подхода) к килю судна при прохождении мелководных ( по осадке) русел для подхода к портам.
Roger Couture almost 7 years ago
I can not wait to see that.
Ananth Narayan almost 7 years 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.
Sava Savov almost 7 years 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.
Don Blankenship almost 7 years ago
maybe they are looking for new or another employee.... hmm? why not test the international waters for new talent?
j t almost 7 years 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.
Marco QM almost 7 years 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...
Husein almost 7 years ago
@Per Wimby Can you give us some rough dimensions of the hull instead draft and beam ratios. We are not all ship architects :)
Sumit Goski almost 7 years ago
What is the light weight of the ship ?
Jamie almost 7 years ago
clarification - is the over displacement weight inclusive of the vessel displacement??
Melville almost 7 years ago
Can we design the ship for North-Atlantic Harsh wave patterns ?
Melville almost 7 years 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
Sava Savov almost 7 years 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.
Husein almost 7 years ago
Is the 6.5 meter draft (harbour restrictions) the vertical distance between the waterline and the bottom of the hull?
Guillaume Florent almost 7 years 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.
Nick Tracy over 6 years 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.
walid youcef errahmani over 6 years 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
Adem Y over 6 years 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?
Dario D'Amico over 6 years 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.
Winston Jennings over 6 years ago
https://www.youtube.com/watch?v=WzIXz0Zc-Io
Ashish Verma over 6 years ago
Same here as @Dario D'Amico
Winston Jennings over 6 years ago
https://www.youtube.com/watch?v=tNxzDQRk2CE
Kesa over 6 years 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
Pedro Henrique over 6 years ago
Kesa, would know when Finalists and winners will be announced?
Laszlo Doro over 6 years ago
Great! I have just came to notice that this is going on.
Germano Pecoraro Designer over 6 years 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
Syamsiprop over 6 years ago
is deadline extended?
Matt Firmani over 6 years 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!
Vladimir Izmailov over 6 years 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
Pedro Henrique over 6 years 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
Regards,
Germano Pecoraro Designer over 6 years ago
Excuse me, Who is the Hull Winner?
Trent Pierce over 6 years ago
Who is the 10th finalist? I only see 9 finalists on the results page.
Adem Y over 6 years ago
I can't believe last 12, some design's unrealistic to building.
Jonathan Ziegler over 6 years 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.
Cad Cam over 6 years 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 ...
Bogdan Tovstonog over 6 years ago
Really??? even not in 12??? Noooo )))))
Sava Savov over 6 years 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 over 6 years ago
Of course I wish luck to my friend Clix
farrux s over 6 years ago
Animation of my latest failure))
https://m.youtube.com/watch?v=mN0oJNRrcLA
dejan jayasinghe over 6 years ago
very good farrux s
Laszlo Doro over 6 years 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...
Adem Y over 6 years 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
dejan jayasinghe over 6 years 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.
Laszlo Doro over 6 years 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.
Adem Y over 6 years 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 over 6 years 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.
Laszlo Doro over 6 years 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...
Bogdan Tovstonog over 6 years ago
Crazy selection of finalists. Some of them are perfect, but some it's hard to believe to be selected by professionals.... Shame...
Laszlo Doro over 6 years 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...)
Bogdan Tovstonog over 6 years 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.
Francisco Inglés over 6 years ago
I love the smell of BARRACUDA in the morning ;-) congrats to all finalists!
Francisco Inglés over 6 years ago
Keep Calm and Let's BARRACUDA !!
Germano Pecoraro Designer over 6 years 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 Designer over 6 years 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).
dejan jayasinghe over 6 years ago
Thanks Luis
Adem Y over 6 years ago
Luis ı hope jury read all comments.
Jesús Miguel Pérez Martín over 6 years 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.
farrux s over 6 years 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! :)
Jonathan Ziegler over 6 years 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!
Laszlo Doro over 6 years 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.
farrux s over 6 years ago
Thank you Jonathan! I really appreciate your assessment
Adem Y over 6 years 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.
farrux s over 6 years 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 over 6 years 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)
walid youcef errahmani over 6 years 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
Laszlo Doro over 6 years 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 over 6 years 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.
Manish M C over 6 years ago
Are we a joke to you did all the calculations manual and submitted ?
Pedro Henrique over 6 years 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.
Bogdan Tovstonog over 6 years ago
Laszlo, I think I know what is in your mind. This grabcad challenges are highly cheating events...
farrux s over 6 years 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?
Bogdan Tovstonog over 6 years 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 ))
Laszlo Doro over 6 years 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.
Bogdan Tovstonog over 6 years 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... (
Adem Y over 6 years 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.
Yacht Design Technology Ltd over 6 years 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...
Cad Cam over 6 years ago
The comments are correct. They probably chose unrealistic plans ... deliberately!
There are several unrealistic challenge finalists.
Bogdan Tovstonog over 6 years 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
Cad Cam over 6 years ago
Fictitious people will win. And they'll steal ideas. It is possible ??
Cad Cam over 6 years ago
Luis Caro
I also checked. I'm much more interested in what's happening here!
Adem Y over 6 years ago
İnteresting, ı just googled stena elektra and this challenge dates are very close.
Laszlo Doro over 6 years 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.
Yacht Design Technology Ltd over 6 years 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.
Laszlo Doro over 6 years 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.
Jonathan Ziegler over 6 years 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.
Sava Savov over 6 years 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.
Yacht Design Technology Ltd over 6 years 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.
Cad Cam over 6 years ago
Luis Caro,
It is very interesting... We don't know what's going on here. Starting to be a comedy.
Cad Cam over 6 years ago
It would be appropriate for the leaders to respond and look over the finalists.
Germano Pecoraro Designer over 6 years ago
Some of the ship's hull designs were taken by Delft Ship, Free Ship, Orca 3D CFD, etc etc!
Laszlo Doro over 6 years ago
Exactly Germano! And that effort was enough for being a "finalist".
Cad Cam over 6 years 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 over 6 years 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 over 6 years ago
Luis Caro,
I can see that too... :D
farrux s over 6 years 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)
Kesa over 6 years 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
Jonathan Ziegler over 6 years 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.
Kesa over 6 years ago
@Jonathan Who did you reach out to? I haven't received any emails from you.
Jonathan Ziegler over 6 years ago
@Kesa, Matt Firmani. I will send you the message I sent him to keep it offline.
Kesa over 6 years 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
Adem Y over 6 years 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.
Sava Savov over 6 years 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 ...
Kesa over 6 years ago
Stena has issued a statement passed on their finalists selection for this challenge.
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"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
Sava Savov over 6 years 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.
Bogdan Tovstonog over 6 years 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 over 6 years 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 over 6 years 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 over 6 years 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 over 6 years 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 over 6 years ago
Thanks Luis. Your work was also very good. But this place is not correct for fair play.
dejan jayasinghe over 6 years ago
agree with you Luis
dejan jayasinghe over 6 years 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 ;)
Yacht Design Technology Ltd over 6 years 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.
Husein over 6 years 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
Germano Pecoraro Designer over 6 years 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.
Laszlo Doro over 6 years 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.
Phillip Shapiro over 6 years 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.
dejan jayasinghe over 6 years 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.
Bogdan Tovstonog over 6 years 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.
Manish M C over 6 years 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 .
Adem Y over 6 years 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.
Michael Dimou over 6 years 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!!!
farrux s over 6 years 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 over 6 years ago
And BIG thanks to Jason)
Sava Savov over 6 years ago
Why the hell someone will scale his model when it will be tested with computer?
Yacht Design Technology Ltd over 6 years ago
This comment was removed
Sava Savov over 6 years ago
btw, it seems i have clicked "report spam" to somebody's post - sorry.
Sava Savov over 6 years 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
Yacht Design Technology Ltd over 6 years 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 over 6 years ago
I would credit Stena Teknik with the capability of being able to equalise the competitors to the same roughness...
Bogdan Tovstonog over 6 years 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?
Yacht Design Technology Ltd over 6 years 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 over 6 years 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
Sava Savov over 6 years 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.
Bogdan Tovstonog over 6 years 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.
Yacht Design Technology Ltd over 6 years 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 over 6 years 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
Trond Svandal over 6 years 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.
Yacht Design Technology Ltd over 6 years ago
This comment was removed
Trond Svandal over 6 years 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.
Yacht Design Technology Ltd over 6 years ago
This comment was removed
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: And what about you design?
Yacht Design Technology Ltd over 6 years ago
that was the first link, about 0.1% too light...
dejan jayasinghe over 6 years 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).
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: You got a really good match, have you tried it in full scale?
Yacht Design Technology Ltd over 6 years 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.
dejan jayasinghe over 6 years 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
Yacht Design Technology Ltd over 6 years ago
This comment was removed
Trond Svandal over 6 years 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 ?
dejan jayasinghe over 6 years ago
YDT Ltd and Louis, I know that. I misread.
dejan jayasinghe over 6 years 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
Yacht Design Technology Ltd over 6 years ago
This comment was removed
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: Nice, what was the final trim and displacement?
Yacht Design Technology Ltd over 6 years ago
Trond - Trim was -0.0233 degrees, sink was 0.231m at the center of mass.
Yacht Design Technology Ltd over 6 years ago
(boat was travelling in positive x, y to port, z up.)
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: you are talking about your design now, right?
Yacht Design Technology Ltd over 6 years ago
Trond, I was talking about yours. My design had 0.075 degrees trim, -0.20m sink
(your ship -0.231m sink)
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: Ok, and COG calculation is based on?
Matt Firmani over 6 years ago
Hey everyone! Just a reminder to keep things friendly in chat.
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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:
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"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."
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Let's please be respectful, and join together in congratulating our finalists. Stay tuned - our winners will be announced shortly!
Yacht Design Technology Ltd over 6 years ago
Trond, LCG was based on measurement of the volume at 16,000 tonnes, I just used zero for ZCG and YCG.
Trond Svandal over 6 years ago
Yacht Design Technology Ltd: OK =)
dejan jayasinghe over 6 years 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!
Adem Y over 6 years 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.
dejan jayasinghe over 6 years ago
hahaha, smoking rizla +, bravo Luis, you made my day :-)))
Adem Y over 6 years 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 :)
dejan jayasinghe over 6 years 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
Laszlo Doro over 6 years ago
Did anyone else run full scale simulation?
(It is not completely clear by the above conversation...)
Manish M C over 6 years 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.
Yacht Design Technology Ltd over 6 years 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.
phickey over 6 years ago
Good Day. Wondering when the winners will be announced?
Bogdan Tovstonog over 6 years ago
Are you ready to be winner? ))
dejan jayasinghe over 6 years ago
it seems like finalists are frustrated too :-)))
Winston Jennings over 6 years 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.
Sava Savov over 6 years 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.
Winston Jennings over 6 years 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.
Laszlo Doro over 6 years 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.)
Winston Jennings over 6 years 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.
Laszlo Doro over 6 years 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.
Winston Jennings over 6 years 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.
Yacht Design Technology Ltd over 6 years 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.
Winston Jennings over 6 years 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.
Yacht Design Technology Ltd over 6 years 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.
Winston Jennings over 6 years 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!
Laszlo Doro over 6 years ago
"That's the spirit, George..."
;)
Winston Jennings over 6 years ago
Guess we all knew what we signed up for...
Laszlo Doro over 6 years ago
(sorry, Luis I just deleted it, did not see your answer)
So: It became quite void for the final, that is for sure.
Adem Y over 6 years ago
Whats happening here :D
Laszlo Doro over 6 years ago
fckd up LVL9000
:D
(I feel sorry for you Louis, of course.)
dejan jayasinghe over 6 years 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/
Winston Jennings over 6 years ago
So, is this radio silence?
Bogdan Tovstonog over 6 years ago
Grabcad banned Luis... It's going lower and lower..
Andreas Morch Hildershavn over 6 years ago
The winner was supposed to be announced on the 11th. What's up with the delay? Must be difficult to select a winner.
Adem Y over 6 years ago
Must be hard selecting winners in 200m bottles and kayaks 😅
Sava Savov over 6 years 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
Cad Cam over 6 years ago
This is a fallen challenge. I'm sorry. :)
phickey over 6 years ago
Good day Matt. Any idea when the winners will be announced?
dejan jayasinghe over 6 years ago
Sava, like I said in comment up above 10min is enough.
KUKI PEREZ over 6 years 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!
Sava Savov over 6 years 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
Bogdan Tovstonog over 6 years 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.
Winston Jennings over 6 years 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
dejan jayasinghe over 6 years 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.
Adem Y over 6 years ago
I guess they're waiting 1april :)
Matt Firmani over 6 years 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!
Winston Jennings over 6 years ago
Simple, rock, paper, scissors!
Bogdan Tovstonog over 6 years ago
They waiting when attention to this "challenge" faded and then to cheat ))
phickey over 6 years ago
Matt. Do you know how much longer before the winners are announced?
Bogdan Tovstonog over 6 years ago
You are winner, don't worry )
Adem Y over 6 years ago
Poor grabcad, worst challenge ever made. :)
Matt Firmani over 6 years 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!
Adem Y over 6 years ago
Absolutely shame challenge for naval architecture. Bye grabcad and ı hope stena teknik tried to buıild that hulls of tjey have enough face.
Michael Dimou over 6 years ago
Bravo guys!!!!
phickey over 6 years ago
Congrats to the winners.
phickey over 6 years ago
Matt - I don't think I'll be doing any of these challenges in the future.
KUKI PEREZ over 6 years ago
oh my gosh, we have winners!!! congrats to the kayaks boys ;-)
Jonathan Ziegler over 6 years ago
This has been by far the most confusing contest I have ever been in. Congrats to the winners, I hope you get paid.
dejan jayasinghe over 6 years ago
Congrats winners!
Bogdan Tovstonog over 6 years ago
I hope Stena will really build their Electra on the winning hulls ))
Winston Jennings over 6 years 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 😌
Clix over 6 years ago
Congrats to the Winners!, Thank you Stena for the opportunity !
Er. Abu Adil Khan over 6 years ago
how to know about the winner ?
phickey over 6 years 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?
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