Best Marine Design Software for Hull Design? (2001-2005)

More Hollows Info

The Solidworks program doesn't use a "net" like Max Surf to dictate the shape. You draw in your sections at the stations you want then loft between the sketches.

Adding half and quarter stations at the bow helps, as does using a waterline as a guide curve. However, the spline still tries to reverse on itself.

I'm sure the program was never intended to perform this function. I'm sure changing the type of "spline" in the program would help. To my knowledge that isn't available yet.

Thanks for the suggestion.

 

The problem with hollows in the bow of designs done with B=spline or NURBS surfaces is common to any program that uses these surfaces, that includes Maxsurf,Autoship,Fastship,Prolines and Prosurf (Nautilus).

The problem is caused by the topology of the surface being rectangular - a corner of the surface is very sensitive to a small amount of twist in the quadrilateral formed by the corner and the three control points adjoining the corner point.

As an example, imagine a design with a plumb stem with the corner point at the bottom of the stem. If you want U shaped sections in the bow, the line formed between the lowest two points in the column of control points just aft of the stem will need to be close to horizontal (viewed in the body plan) coming into the hull centerline. However the second lowest point in the stem will be verticaly above the corner point.

If you just consider the quadrilateral formed by these four points, it will have to twist through 90 degrees over a small distance. It is this extreme twist that causes the waterline (and sectional) hollow.

The simple fix for this is to move the second lowest point down so that it is co-incident with the corner point. The quadrilateral is transformed into a triangle, and a triangle cannot exhibit twist. The less twist you have in a corner quadrilateral, the cleaner the surface will be in this area.

It is difficult to explain this problem in words alone. I have attached a jpeg which I hope illustrates the problem and its fix.

Andrew Mason
Technical Director
Formation Design Systems

 

:idea: Thank you Andrew, I have to go try this right now.

Gary

 

Thanks Andrew

Outstanding!

Your description was very clear, even without the jpegs.

I hope everyone here recognizes your significance in this whole "design boats with CAD" era. You have really been a trailblazer. The group here is lucky to have guys like you and Mr. Vacanti stopping by here.

You probably don't remember me, but I worked in a California design office in '85/86 when you first provided MaxSurf for boat design. I believe a race boat linesplan developed in that office was subsequently used in your early advertising. I know you worked very hard to make the program useful to real, working designers. Your support was terrific, even before the internet.

Again, thanks for the answer.

 

Paul

Thanks for the kind comments. I'm pretty sure I remember you, I certainly remember the boat. It has been one of our standard sample designs for over 15 years and has been used as the starting point for more yacht designs than I could count, including several America's Cup winners.

regards

Andrew

 

I think you were fortunate to hook up with the right designer at that time. Working with genius is often a plus.

I think that linesplan you used would look something like this in SW:

 

Paul

I can't get that link to work, can you try it again.

Thanks

Andrew

 

Pics

Sorry Andrew, the Yahoo Photo gallery is acting up. I could see the picture until I cleared out my cache. I'll put up a couple of shots in my gallery for you to see.

 

Paul

Look familiar? maybe a bit wider in the transom, but pretty similar.

 

Very familiar

I've hidden my cut off on the stern profile and deleted the bottom paint. The shapes look quite similar now. I'm posting the photo in my gallery since I can't seem to get Yahoo Briefcase back up and running today.

I think you are definitely working with the better tool, and perhaps even more skill!

 

Re: Best Marine Design Software for Hull Design?

The only mentioned program I worked with is Defcar. The module for hull shaping is rather good, but in my opinion there should be some additional options for making surfaces like cone or cylinder. There is also no possibility of smoothness checking (except an optical method). As I know all these functions are available in MaxSurf.

Adam Slipy
SeaTech Engineering
Poland

 

My experience is almost exclusively with AutoShip/Yacht (DOS->8), but I've never really had a problem with hollow waterlines. After several thousand hours I've probably figured out how to avoid most of the problems and forgot about them.

Most problems with hull surfaces are caused by using too many control points. I got pretty good with AutoShip at uni and several of my classmates asked me to help them fair their horrifically lumpy final year projects. In every case the first thing I did was delete between 60% and 80% or their control points. Just doing that improved their designs dramatically (I did a lot more of course ).

A good way to start a hull surface is to have one more column and row than the degree of the surface, so for degree 3 use 4x4, for degree 4 use 5x5. It's almost impossible to make such a surface unfair. Just use that to get as close as you can to your desired shape then tweak it by adding extra colums or rows with the 'refine' function, which starts them out perfectly fair.

And speaking of fairing, the 'porcupine plot' is only useful if the curvature of a surface is of a similar order, so if you want a radiused stem or something, just leave it off and have an open pram style bow until you're happy with the rest of the hull, then add columns to the front and build the radius. Otherwise you'll have 'quills' sticking out around the bow radius and nothing at all on the hull itself.

Just felt like sharing that - lol

I tried posting a pic here but it doesn't seem to work on this forum for some reason.

 

if anyone knows how works tha model maker 5.1.0 in aytohydro please contact with me in to my mail......................thanks

 

Folks,
I'm proficient with CATIA V.5 software. Is there anyone using this software for marine design???
Darryl

 

I think a mix of multiple programs provides the best results.

for example, to develope a good set of lines you need a program like Fastship, MaxSurf, of AutoYacht. Yet to develop an internal arrangement, deck, and superstructure you need a program like Rhino, Solidworks, or Pro/Engineer. In addition, to make pretty pictures of your conceptual design you need a rendering program like Flamingo of 3D studio!

It seems as though Rhino is the best at importing lines from other softwares and definitely deserves two thumbs up in terms of ease of use! It is also super affordable and interfaces seamlessly with its rendering pakcage Flamingo!

My two cents....