Lofting Technique

[tuhin.name]

Dear Members,

I am a novice in the field of construction. The problem i am facing is, i have

- A lines/Frame plan i. e. station at every frame in AutoCad system.

Now i want to develop the shell plates for a particular plate size and want to have templates for checking during bending so that it can easily fit on the hull.

And particularly one thing, Marking of the frame line on the straight shell plate so that after bending it resembles the real frame.

I know there are many software that can do it. But i want to understand the process. If any suggested readings or document please name it. I am waiting to have an answer.

[alangluyas]

Hi Tuhin.name

I think we need more information on what you are trying to achieve. Is the hull a chine form or round bilge? You say bending the plates. Do you mean rolling?

From the brief information you have given I would suggest you download a free version of ProBasic, ProSurf or ProLines from New Wave Systems and plug your offsets into that to re-create the hull. With one of these progarms you will be able to develop any of the plates shapes and mark on it any lines you want to.

The geometry of doing it from the beginning is tedious but not difficult but I can not see why you would bother to "re-invent the wheel"

If you are familiar with Rhino3D, then by all means use Rhino as it is avery powerful and flexible tool, but if you can't, then the learning curve is steep.

Good luck

Alan Gluyas
Professional Marine Surveyor and Amateur Designer
Fremantle Western Australia

[tuhin.name]

Dear Alangluyas,

Many many thanks for your reply. The hull has a round bilge, a bulb and a skeg. And instead of bending it would be rolling. I have attached a JPEG image of lines plan for clear understanding.

I have only one tool available and that is AutoCad! And i can not affort to buy a software. As far i knew in Shipyard peoples have some techniques to develop the shell plates from lines plan. I want to learn that but no loftman is available around me. May be this procedure will involved some error but that will not bother me.

Actually, I want to learn the techniques, i do not care if these are tedious.
I really need help in this regard.

Thank you for your reply again.

[daiquiri]

Hello,
I suggest you to look out (www.google.com :) ) for papers written by Martin Kilian. He is a mathematician at Vienna University of Technology (Austria) working actively on new algorithms for developable surfaces and has written a number of papers which explain the problem from mathematical point of view. If you are so eager to learn more, you could contact him and ask for help.

[alangluyas]

Daiquiri - thanks for that - this one is beyond me.

Tuhin.name - you sure like big projects. While I am sure that there is a science that will do this, I am a mere amateur designer and boatbulder, and I am accustomed to dealing with much simpler hull forms than this, which appears to have a combination of flat panels, cylindrical and conic develpments and some extreme compound curvature in the bulbous bow and stern sections. I don't know of any commercial software that will allow you to achive this accurately but I don't have any experience with construction on shipyard scale.

I would be very interested to hear how you fare with this problem and I am sorry I cannot offer any advice.

Cheers

Alan