23' Ply Sports cruiser

Looking at building a boat using the Stitch and Glue Method. My design looks a little like a baby Wally power, with an 8' beam, 1 double cabin and head, sterndrive.

Are there any short courses anyone would recommend I enrol on? Most courses and websites look sail-boat orientated.

 

Read Payson's "Build the New Instant Boats", it's a great introduction to the tack-&-tape method (a variation on stitch-n-glue, except with panels that fit together perfectly without the wire stitching). I'm not aware of any courses dedicated to this type of design, not in your area at least.

 

Tack and Tape uses polyester resin. Is this an advantage over epoxy? I'm not worried about price.

 

Both of these techniques (t&t or s&g) can use polyester, vinylester or epoxy resins. In general: Polyesters are the lowest grade resins; vinylesters add considerably more water resistance, and epoxies are very waterproof and are the strongest of all.
Epoxies are also the easiest to use, in my experience. A typical boat epoxy will be perhaps a 5:1 ratio of resin to hardener, and many systems come with pumps or measuring cups that automatically give you the right ratio. -ester resins use more like a 200:1 catalyst ratio, so 10 or so drops of MEKP must be perfectly, uniformly mixed with each working can of resin. Mess it up by a drop or two and it'll either set in the working can, or take a week to cure. They're also very temperature sensitive while laying up and curing. So if you can afford it, epoxy is the way to go, regardless of whether you use t&t or s&g methods.
The main advantage of tack&tape over stitch&glue, imho, is that with tack&tape plans there is no wire stitching- the panels are shaped to fit perfectly with simple bending only. It is the glass that holds all hulls of this type together, the wire and nails are just to hold things in place while the fibreglass is applied.

 

Cheers Marshmat; Another question is weight-what is the thinnest marine ply I can get away with?

 

Actually, Billymac, you are likely going to have a succession of over a hundred questions. Not that anyone here wouldn't step-up to help you with any of these, you may want to do some significant research into the methodology of S&G building by doing some reading.

Start with any proper book on the subject such as Devlin's Boatbuilding and read it through to get the flow of things. Any Google search or Amazon search will yield plenty of others. I woudl also suggest you look at Renn Tolman's, Alaska Skiff, book. It includes plans for a couple of his designs, I believe.

As to scantling needs for a serious offshore powerboat... well, that's another entirely different animal and requires a lot of work to get the whole picture. What would be far better would be to trust in the services of a competent designer of boats of this type and/or get your hands on a set of plans for something that gets you in the ballpark as to your needs.

Learning boat design to do one boat is a pretty unusual way to spend your time when there are already tons of good boats out there waiting to be built from nicely drawn plans.

If you really want to go the schooling route, there are a couple of correspondence courses you can take in boat design. Westlawn and the Yacht Design program from Macnaughton are very good starting points in your search.

 

S+G

1) Make/Buy Plans
2) Cut pieces
3) Wire together
4) Run Fillets (epoxy/filler mix)
5) Grind off Wires
6) Fiberglass tape over fillets
7) Sand + Paint
8) Go Fishin'

See its easy!