plywood jonboat

[nc2ron]

i have been researching (constantly) building a plywood jonboat. i plan to make it 4' at the bottom and 16' long. i have the basic design in my head just from looking at so many websites but i have a tech question that i haven't seen an answer for. " i'm thinking of using 3/8" plywood for the bottom with a 2"x2" framing system on top of that with 1 1/2" styrofoam building insulation in the framing voids with 1/4" plywood on top of that as my floor. will the styrofoam insulation help enough with flotation enough to offset the added weight of the double floor system? there are a lot of gators and snakes where i fish and i would prefer more between them and myself than just a piece of 3/8" plywood. thanks in advance for any input.

[cyclops]

As for your worries of snakes. They do fall into a boat if you startle them in a tree and they try to drop into the water, but plop into your boat by accident. Cure? Do not cruise or stop under trees. Gators and Crocks pick on a smaller and easier meal than something 4' X 16' X 2' with a ugly thing in the middle .-------------------------------- DO not drag a stringer of fish around in Gator waters. The struggling sounds of the fish will draw attention. Use the kill and put them on ice routine. Anything COULD happen. You would REALLY REALLY have to be the unluckest person in the world.

[cyclops]

Oh yes. I was stationed in Dam Neck, Virginia. DO NOT sit still on a dock with a stringer of fish after sundown. Never saw so many water snakes chomping on them in the water. Became a daytime fisherman.

[nc2ron]

the snakes and gators was more sarcastic than anything. i know to leave 'em be and they'll do the same. still gotta think about that sometimes, though. anyway, any comments about my subject question?

[cyclops]

Single bottoms are the normal, in the size and type of boat you want. Use the best sheets of EXT. AC out of a stack , REAL plywood, and Enamal paint. You may want to screw a 2" X 2" keel down the middle for taking beaching and rocks. Concrete ramps eat paint and ply if dragged on them. Most center roller trailers do less damage if the 2 x 2 is there. Screws, a small bead of Silicone Rubber on the pre-painted keel and fill the screwholes. Done

[Deering]

Answer: yes. The foam will be plenty of flotation, but you want some flotation up higher under the gunnels as well. to provide upright floatation when swamped.

[nc2ron]

don't plan on swampin' it in the calm waters i fish. but that is a good idea anyway. i'll have to think of a way to add that to the design i have in my head. got so much info inside there already, i better start writing some of it down. thanks

[Chris Ostlind]

Here are a couple of jonboat derivatives I have done specifically for fishing applications. The orange boat is just shy of 16 feet in length to take advantage of getting the hull panels from a two sheet layout. The blue boat is an 18' design that has a raised deck with a stringer matrix underneath for hull integrity and the ability to carry a larger engine.

As you can see, there is a bunch of enclosed volume with the different styles of fishing platforms and side boxes. You can permanently enclose any or all of these spaces for needed flotation according to the designed loads you will be carrying (including the weight of the engine) The rest of the volume can be used for gear storage, bait tanks, catch tanks, ice boxes, etc.

Chris Ostlind