Questions about kayak building

[ctoddh]

I am working on a kayak for duck hunting in flooded timber areas. This needs to be a relatively flat bottom kayak due to the area it will be used in. I am planing to build the ribs out of marine plywood cut on the bot and use cedar strips covered in fiberglass for the shell. My biggest question is about the bottom, since it is a flat bottom boat is there any advantage to using a solid piece of marine plywood or other plywood covered in fiberglass, or should I use the strip cedar on the bottom also. I am not sure about how this would affect the weight and stability. I am new to boat building and was wondering if anyone out there could give me some suggestions or pointers. Thanks,
Todd

[Wdyasq@yahoo.com]

Gee Todd,

Recommending boats is sort of like recommending girlfriends......

That said, I like plywood. The toughness of plywood is hard to beat. It is also a good topside material. Cedar strip and glass is a fairly labor intensive method and you have the opportunity to bathe yourself in epoxy and inhale cedar dust. This is loads of fun and can invite health problems...OK, I lied about the fun, but this is an opinion.

If I were building a boat for this purpose I would build all plywood. I would use poly-propylene (I think) cloth as bottom sheathing. The boat would be as light if not lighter than a strip-plank boat and more durable.

If you haven't been to Bill Young's site, http://www.seasidesmallcraft.com/ it is worth your visit. I would also visit WoodenBoat's catalogue and see what plans they had to offer.

And, when you buy the plywood, buy the "Good Stuff". The imported metric plywood built of Occume or some other good wood, properly built and glued is, in my opinion, far superior to the fir plywood sold as "marine plywood".

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[billp]

Todd, I'll second Ron's thoughts on the matter. The only real advantage cedar strips have over marine plywood, is that if you do a neat job, it looks better..Yes you might be able to creat some curved shapes that plywood won't twist itself into, but it sounds as though you aren't going for a Whitehall or similar hull shape.
Ron is also on the money about using the good plywood as well. I use Okume plywood exclusively, and I bond it with MAS epoxy. I have tried ALL the other brands over the last 30 years, and it is the best, no question. Sands easily, and you can clean up your hands and tools with white vinegar too.
Two last thoughts to consider; if you go to www.clcboats.com, you'll see the web page for Chesepeake Light Craft. They have sold about 8,000 kayak/canoe kits to date, ALL in plywood. And you should defineately contact Bill Young and ask about "Scout", which is a kit he produces for a beautiful, flat bottomed, "gunning" boat which sounds exactly like what you are looking for. If it's your first boat, go with a kit. What you will learn in the process will allow you to make up your mind regarding future marine endeavors..Bill P.

[Wdyasq@yahoo.com]

Todd,

Bill is more familiar with recient developments in the boat kit industry than I am. The designs were built to work on the water and that hasn't changed. Kits take a lot of the time and trouble out of a person's first boat. Just knowing the proper epoxy can save a lot of headaches.

Building a boat from scratch takes a lot of time. There are many learning steps. Each takes just a little more time.

Thanks for the tip on MAS epoxy Bill. I have never used that brand. My favorite right now is System3.

And, so what is so dificult about a Whitehall? Other than the lofting, the reverse in the frames, the twisting of the garboards and a few other minor things......

Ron

[bill.young]

Todd,

I've got to agree with Bill P. and Ron. Plywood is a great boatbuilding material that can be used to build some very interesting hull shapes; check out http://www.stillwaterboats.com for a neat example.


I personally would recommend building the whole boat out of plywood, but I would definitely use it if my design had a large, relatively flat bottom panel. It would be a lot stronger and would give a smoother finish with MUCH less work.

Good luck and let us know how it turns out.

Bill Young

[billp]

Todd, just in case we haven't convinced you of plywood's capabilities, you might want to try these two web sites:
http://carlsondesigns.com, and http://home.clara.net/gmatkin/hullstut.htm
On the first site Gary Carlson has actually posted a FREE boat design program called "Hulls'which has a library of existing hull shapes ( including the infamous Whitehall, etc.). You can not only edit, and change any dimension you'd like on the screen, but you can also save the plans as .dxf files, and cut them on your 'Bot!!!I have done so before, and it sure beats reinventing the wheel.
The second site is another great freebie from Gavin Atkin in England. He has written a tutorial on using the "Hulls"program which should get you designing pretty quickly. As with any program like this I'd try to create my shape in a smaller scale, (and a less expensive material such as 1/8"ply ) first, before getting out the Okume..
If there is any more interest in boatbuilding stuff like this, please let me know via the Forum, and I'll paste some great links that will give anyone planning to build a boat some great info...

[billp]

OOPS. the URL I just posted for Gary Carlson is incorrect. It should have read-http://www.carlsondesign.com, sorry for the typo

[ctoddh]

Thanks for all the great links and suggestions. All the info I had to date was from duck hunter resources and I figured it would be better to seek advice from boat builders. You guys have given me lots to think about. Thanks again.
Todd

[Wdyasq@yahoo.com]

Todd,

I do want mention one thing about stability and boats. Round bottom boats are squirrelly. I used to have a light, round-bottomed dingy I would loan to folks and take bets with the locals if the person would end up in the boat or the water when the person borrowing the boat stepped in. I always took the water end of the bet. It wasn't long till no one would take the bet.

If you have never been gunning in a boat, put a life vest on BEFORE you get into the boat. Until you get the hang of it - tie the gun to the boat.

There are several factors involving stability on flat bottom boats. The most noticeable is how wide the bottom is compared to the sheerline width. That is, how vertical the sides are in the center. The more vertical the sides, the more stability the boat will have. Some workboats have wider bottoms than the sheer. They are extremely stable.

Ron Brown - wdyasq@yahoo.com (mailto:wdyasq@yahoo.com)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers