64 in Custom Mono-Hull Build, Help!!
 

Hey everyone, I'm kind of stuck on finishing my hull and would like some advice. I'll include more detail below but here's TLDR. I have the hull frame for a heavily built large monohull done and I need to sheath the hull with something. I need to cover the fames with something, balsa, plastic, thin plywood etc. to smooth out the profile before I finish and seal it with some carbon fiber and epoxy resin I have laying around. If yall could recommend techniques you've used or better yet link to a build thread showing said technique that would be awesome! Thanks.

Enjoy the build pics, and yes I know its way over built but this isn't for a traditional application.


1) 64 inch LOA planing stepped monohull hull form designed in CREO
https://cimg6.ibsrv.net/gimg/www.rcu...0df62edfc9.jpg


2) Hull framing keel and stringers cut from the solid hull form. Complex geometry around bow and hull steps retained to be made on 3D printer
https://cimg7.ibsrv.net/gimg/www.rcu...6a99d4fe04.jpg

3) Arrangement and numbering of frames and stringer
https://cimg8.ibsrv.net/gimg/www.rcu...b427d1703a.jpg

4) Placement of 3D printed complex geometry sections
https://cimg9.ibsrv.net/gimg/www.rcu...b81a9ea50a.jpg

5) Placement of 3D printed bracing pieces
https://cimg0.ibsrv.net/gimg/www.rcu...838f9ba8b5.jpg

6) Frames and stringers cut out of plywood, A sections in 1/4 and B sections in 1/2 in all birch
https://cimg1.ibsrv.net/gimg/www.rcu...5cf785cb3e.jpg

7) Stern frames and stringers along with transom and keel comes together. Grey 3DP parts are used to add strength as well as correct relative angles.
https://cimg2.ibsrv.net/gimg/www.rcu...a1394c1a5f.jpg

8) Frames B section are installed moving up from fore to aft
https://cimg4.ibsrv.net/gimg/www.rcu...641deb52fb.jpg

9) Front stringers are added
https://cimg5.ibsrv.net/gimg/www.rcu...4a23ab473f.jpg

10) All 1/4 inch A sections are wedged between the B sections for test fit. All parts dissembled and then reassembled with waterproof wood glue
https://cimg6.ibsrv.net/gimg/www.rcu...901e1b4244.jpg

11) Glued and dried hull frame with 3DP complex geometry areas test fitted.
https://cimg7.ibsrv.net/gimg/www.rcu...9be5e42e16.jpg

I was tremendously pleased with this result as this is my first time building a boat and doing much woodworking at all. It came out very strong for its weight and will serve my purposes fantastically.

I am unfortunately a bit at a loss as to where to go from here. I went off a bit half cocked on this project assuming that sheathing and finishing the hull would be the easy part. I need to sheath the hull with something. I need to cover the fames with something, balsa, plastic, thin plywood etc. to smooth out the profile before I finish and seal it with some carbon fiber and epoxy resin I have laying around. So far, I have tried the thin flexible plywood. I didn't seem to conform to the shape too well with a geometry I tried to cut. Before putting too much time and frustration into it I figured I'd throw it out to the web and see if you guys had seen or done something similar If yall could recommend techniques you've used or better yet link to a build thread showing said technique that would be awesome! Thanks.

Aircraft grade 1/16th inch thick plywood works well for your application. I use it to skin hydroplanes like the one linked below:
https://www.rcuniverse.com/forum/att...4&d=1375582341

I was always taught that it was customary to use mahogany not birch in boat structures. I always used mahogany in mine, even as a kid in high school 60 years ago.

There are several issues with building out of mahogany:

• it's heavier
• it's much more brittle than birch
• in the thickness' we use for models, it won't bend around compound or tight curves without breaking
• unless you buy mahogany door skins, which are pretty much a cheap grade of three ply plywood, it's much more expensive

I don't know of anyone that's built an R/C boat using mahogany for skin panels. What I have seen, numerous times in fact, is to build the boat out of birch plywood and then glue veneers that are almost paper thin to the outside. The birch is used to take the stress and the veneers give the appearance of a mahogany boat.
With that said, I know many of the classic hydroplanes and earlier Gold Cup boats were made from mahogany. The catch was that they were skinned with .25" thick plywood with brass, copper or aluminum bottom sheathing to protect the wood. When I helped restore the Slo-Mo-Shun V, that was how we did that boat as well, the exception being that we used plywood that was custom cut at a 45 degree angle to the wood plies instead of the standard 0 and 90. Needless to say, the custom cut plywood was close to $100 per sheet so we had to make sure we were very careful on how we used and cut it to keep costs down since we used roughly 14 sheets to deck the hull. The results of how well we did in restoring the boat speak for themselves when you see it at the Hydroplane and Raceboat Museum