View Full Version : flat plane dimension from scale model - literature source

12-09-2013, 02:47 PM
literature Source ?? I was just reading "Devlin on Boat building" and there is a chapter about making a small scale model of a boat. From the model, one can get the flat plane dimensions of plywood slabs for the hull. ???? Is there another literature source explaining this method/procedure ???

I want to know what type material, readily available, (not $150 sheet per half sheet of 1/8" super plywood) a person might use and the procedure for making the scale model and the full size surface.
I do not want to know the second derivative of a Gaussian surface and conic projections philosophy.

Peerie Maa
12-09-2013, 02:49 PM
What do you mean by plywood slabs for the (full size?) hull?

Gib Etheridge
12-09-2013, 04:42 PM
Sounds like a hard chine hull where you can scale what you need for plywood panels for sides and bottoms from the model. One way to do that would be to remove the planking from the model and trace it onto a grid to scale. Another would be to mark a grid to scale on the panel before fitting it to the model then get your dimensions from the grid once it's on the model if it's glued on and can't be removed.

12-09-2013, 04:55 PM
What you talking about is Multiconic Development of hull surfaces. This is the process of turning curved surfaces into flat (Developed) patterns or turning flat patterns into curved surfaces (a boat hull of one or more chines. The classic literature on the subject and it's use in boat hulls was written by Samuel S. Rabl but Sam Devlin also wrote a good illustrated piece on the subject for WoodenBoat.

http://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CC0QFjAB&url=http%3A%2F%2Fwww.boatdesign.net%2Fforums%2Fatt achments%2Fboat-design%2F57463d1306296049-need-formula-figure-out-blow-aluminum-hull-plates-side-plates-rabl.pdf&ei=izumUuOMNpLnoATxm4LIDA&usg=AFQjCNEvCP7cVRNc_M0EtYmpmSK2nhDv5A&sig2=SqD_AsBk1Z73iPSO1CWYDA&bvm=bv.57799294,d.cGU

12-09-2013, 05:07 PM
Another source on the subject.....


12-09-2013, 05:11 PM
^Bookmarked, thanks for the Rabl article, Tad.

The article by Sam Devlin is in WB 106 entitled "Converting to Stitch and Glue" wherein he converts the Ted Brewer 22' Cape Cod catboat to stitch and glue.

To think of all the work that Jim Ledger could have saved:D

12-09-2013, 05:44 PM
What do you mean by plywood slabs for the (full size?) hull?

I mean one piece of plywood to make the side of a skiff. No lapstrake stuff.

Peerie Maa
12-09-2013, 05:55 PM
I mean one piece of plywood to make the side of a skiff. No lapstrake stuff.

OK, the word "slab" confused me, I am used to them being called panels.
You can build a model, and wrap stiff paper or thin card around it, then when the card lays flat you will get close to your shape. When you scale up, leave some "green" around the edges to allow for inaccuracies.

Or you could follow Bruce's system and start with flat card panels like this: http://forum.woodenboat.com/showthread.php?146586-Wizbang-MK-2-new-build&highlight=wizbang

12-09-2013, 06:10 PM
The Gougeon Brothers on Boat Construction book has a chapter on tortured ply at the model level. They offer the book fro free as a pdf download now. And when you get around to building it, you can get some model airplane plywood to do the build (it's expensive for a big sheet but you'll use little of it). I'd try to get close first using cardboard though.

Mad Scientist
12-12-2013, 05:54 PM
Link to the Gougeon Brothers' book: http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook%20061205.pdf


Tom Lathrop
12-12-2013, 06:45 PM
Sam uses the "lift" method from the offsets to build the model. Just follow his directions and you can do the same. Excellent aircraft plywood in proper scale thicknesses of 1/32", 1/16", and thicker is available from Aircraft and Spruce Supply as well as Wickes aircraft supply. I like 10mil Mylar to take off the panel shapes but greeting card stock (Staples) also works well if kept dry. Card stock is even better if you put on a protective coating like shellac or varnish.

Peerie Maa
12-12-2013, 06:53 PM
Or you can put the offsets of the keel, chines and sheer into Free!ship, and have the software do it for you.