Replies to This Discussion

Permalink Reply by Duane Doran on September 16, 2012 at 5:46pm

We do this all the time and you are correct in that it saves a lot of time. Most 3D CAD systems allow you to export a 2D view of your drawing to make a paper template. If you want to go really high tech then find someone with a CNC Router Table. You can create a tool path right from your drawings and cut your pieces without ever toughing a saw. And they will be perfectly sized if drawn correctly.

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Permalink Reply by Dave Z on September 17, 2012 at 5:13pm

Michael,

I'm an engineer by background, I use Autocad, Pro-e and a slew of other modelling programs.  Guess what.... When I design my hulls, I make a manilla folder model, however, it is not haphazard- I can usually get it right pretty close to the first time now. I built a few scaled-lumber models, but have recently skipped that step and went straight off the paper hulls.   

When I design a hull, I sketch it out on paper, but I am always aware of my material limitations, and actually design my boats around the material sizes-  4x8 sheets of plywood, accounting for a scarf, etc... I want the maximum use of the wood with the minimal amount of waste.  (why design a sheer of 16 ft - 0 in when you will actually have to scarf twice to get there?)  If you look at any of the lines for my designs, you will find the measurements and station lines are in obvious and even intervals.  That is on purpose.

Dynamite, as mentioned formed half hulls, this is what ship builders did and actually still do in some cases.  The carved wooden slug allows exacting measurements to be taken (paper boats flex!).

Many ways to do it... Some guys can visualize the 3D renderings on a computer screen, others of us have to see it in form.  Good luck.  No wrong ways.

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Permalink Reply by Sandy Pittendrigh on September 29, 2012 at 7:36am

I just noticed this thread.  No one mentioned full size models. 1/12th scale models are easy and useful too.  I'm a retired software engineer, among other things, so I'm not intimidated by software. But I still don't like it.  I spent three years writing 3D imaging software in OpenGL and OpenInventor.  So I know the ropes.  The good software is too expensive and the cheap too cumbersome.  And I never really know by looking at a monitor whether I'll be happy with the eventual boat or not.

With full size models I know.  I use adjustable ribs, splined in the middle and hinged at the sides. Then I cut out some tentative side panels and attach them to the ribs.  Attach tentative transom and stem (all with sheetrock screws) and mess with it until it looks right.  Then I attach a bottom and slobber it with resin, cover it with fiberglass and then paint it and row it. Works every time. A more detailed account can be found here: http://montana-riverboats.com/?page=Driftboats/NewHullDesigns

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Permalink Reply by Duane Doran on October 3, 2012 at 1:18pm

I can't speak for TurboCAD but most 3D programs I've used include the ability to print 2D drawing files and create templates on a large format printer. We use Alibre Design from 3D Systems and for the boat's we've designed creating a tool path and using a CNC Router is far faster. There are a number of companies who will take your files and do the cutting for you. It will vastly expedite your build time and provided the files were drawn correctly will provided amazing precision.

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Permalink Reply by Brian whitus on October 16, 2012 at 6:51am

if you only have a 2d cad program, it is possible to create flat patterns using 2d drawings and a process called triangulation.  the process is tedious but it will work...

basically it works like this - let's say you want a pattern for the bottom -  

1. you break the bottom surface into triangles,

2. obtain measurements from known points on the bottom surface using 2d profiles like a plan view and side view (these points make up the triangles and you have to be able locate them on your drawing profiles),

3. calculate true lengths between these points (you will need the distance between 2 points in the plan view and the elevation change between these two points from the side view)( I use excel to calculate the lengths - length = sqrt( (Lxy)^2+ Z^2), where Lxy is the distance between two points in the plan view and Z is the change in elevation between the same points. 

4. reconstruct your bottom surface using the true lengths between points.

The smaller the triangles, the more accurate the pattern, but also the more tedious... there is information on the web that explains this better than i can.  i have tried this method only a couple of times and was able to make a flat pattern that i printed out at scale. the sides and bottom were attached and fit together perfectly. You will need good 2d drawings of your proposed boat with developable surfaces and a lot of patience.

Sandy makes a good point about building with adjustable ribs to change the shape during construction.  It is easy to spend a lot of time on a computer trying to get a perfect design or shape, when you could use that time to construct your boat.... you can get hung up and spend a lot of time on the computer for minor things...

For me it is the challenge / process of design that I enjoy. plus when using the computer, it allows me to construct a boat digitally without investing in the materials.... i have built one stitch and glue and the wife doesn't yet see the need for another boat....

Good Luck.

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Permalink Reply by Michael Rosso on October 16, 2012 at 7:13am

Brian,

If you already have a boat, I doubt your wife will EVER see the need for another unless you sell your current boat, or damage it beyond repair.   Women are inconveniently practical like that..

Your approach does seem a bit tedious.   As far as Sandy's approach, I have a nicely sized workshop but when there's a boat being made it gets decidedly smaller!   If I begin to build a boat it will be designed in full beforehand in order to minimize it's time in my shop.   This is one of the biggest reasons I would rather not use a strongback again.   I like the idea of cutting, scarfining, then finishing sides, bottom, transom and ribs BEFORE they go together.  

Thanks for your input!

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