Ship hull Loft Problem
Hi there recently i am workin upon a ship hull project and i am facing a problem with the loft feature and specifically some kind of anomaly. Dont have in mind what is the fault. Possibly need more guide lines??
I present you 2 photos with the problem.
The construction made up of many profiles each of them is connected with guideliness.
Looking at the additional images, I see you're attempting to construct a bulbous bow hull. This hull typically has a flat bottom portion, not a 'V' and though ships are typically drawn as lofted sections for construction purposes, they are rarely constructed in CAD this way.
Let me just put it this way... the more sections you have, the greater the chance for anomalies in the surfaces of your 'loft'. It's better practice, IMO, to build surfaces with fewer sections (enough to define the transition of desired shape) and 2 guide curves.
Your ship 'sheer plan' and 'half breadth plan' are typically what you'd use to construct the section splines. Half breadth gives you 1 spline. Sheer plan gives you another. The two are combined into 1 3d spline. Build the sides, then build connecting surfaces to g1 continuity to the flat-bottom portion.
I may go into this with an example if I can find the time.
5 Other answers
In SW, it helps hull lofts a whole lot to create guide curves for whatever number of cross sections you use. For example, use the sheer corner points as points in a 3D spline, separate splines for each side. Your cross sections seem to have a flat side throughout, so the tangent between the flat side and fairing curves of the profile will give you a very useful guide curve, since any unevenness will clearly show up in a 3D spline and can be isolated and corrected for each profile in relation to the rest.
The guide curves make fairing the hull much easier. Smoothness is the name of the game in hull contours. Use the keel bottom point for yet another guide curve (all the above curves will be very handy when creating the structural members. It is generally more practical to create your hull shape as the inside surface of the plating (if metal) or planking (if wood). I hope this helps.
The first thing you need to do is to adjust the color scale in your curvature, because when you look at the way it is now, you cannot see anything. Go to options, document, model display, Curvature. set black to 0.0001, grey to 0.0004, blue to 0.001, green to 0.01 and red to 1.00. If that does not work, use view, display, zebra stripes.
Yes, you need to use more curves and more cross sections, for boats you can get away with 20 segments or so (21 cross sections including both extremes). I cannot tell from your pictures what is the general shape you are after, and the choice of curves is totally specific; it may be that you need curves to better define the bottom as well as the sidesif you could post a picture showing all your curves I may be able to help you further.
A couple of things that come to mind. One being the number of segments in each section. You will want an equal number in each sketch. If not, you may use a tool that combines segments creating one 'spline'. Sorry, SWorks was about ten years ago for me so I can't provide the exact tool name.
The other solution might be to build two sections, then build a bridging type section between, in which you can control the continuity.
Posting the SWorks file might get you more exact answers. Good luck.
Alexander this is the ship hull construction.
A big part of your problem is apparent. Once again, I have no way of knowing what the actual geometry of the cross section is - are you using arcs, splines, straight lines? Do all the cross sections have a different number of segments/points?
Where are your tangent points in each cross section?
One thing is sure. You will never get one surface that will maintain a smooth curvature with your cross sections -the shape changes too much for that.
You need to produce a surface (or surfaces) that connects the bow dome and bow profile to the rest of the bow, say, up to your second cross section. The shape of the rest of the hull actually needs to match the tangencies in that surface. because of the changes in the shapes o f your cross sections, you may need to produce three other separate surfaces in order to keep the shape smooth.
With a radical shape as yours, you may want to seriously consider producing your surfaces for only one side of the hull first and then mirror it - complex curves can have minor but significant differences from one side to the other, even with perfectly symmetrical cross-sections.
Also, in your cross-sections, if part of the profile is a straight line, you do not want to create them as part of splines-they would never work as a straight segment.
That is about all I can tell from your pictures.