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Re: 3 mm vs 4 mm plywood?
By:lee
Date: 10/13/1999, 1:04 am
In Response To: 3 mm vs 4 mm plywood? (Nathan)

hi nathan, a quick answer with tangents, yes, but not if you don't need the strength. Go ahead and make test panels then break them. The other part of the question is , what strength do you need? If you are a heavy person or someone that is not delicate that affects your requirements for strength. If you never intend to carry lots of stuff or land on rocks or lever another boat on top of yours then you can make your boat a lot lighter than one that is used for all of the above plus more. I figure i should be able to walk any where on my boat and not freak out. Haven't done it, but I like sturdy.

I built a North Bay with 4mm bottom,3mmsides and deck. I used fewer carlins and more light glass as reinforcement for the back deck, but i added toerails and an extra layer of reinforcement down the center bottom 2" that was painted with lots of graphite epoxy(don't ask why, it was late)I sealed all panels lightly before assembly and made sure to use only the epoxy necessary. So i have a pretty sturdy,average light boat, shifting priorities kept it from being super light. When the boat was finished i had lots of epoxy left over. I also had a slightly darkened deck by the middle of summer because I forgot to open the hatches for a week, the 3mm deck was not sealed well enough. The hull is not as ding resistant as other boats that i have made that were well wetted out on bare wood. Some of that has to do with 4oz cloth but not entirely, a coho i made had the same cloth, the wood was saturated more. I think you could save weight by not bothering with bulkheads/hatches and going for a sea sock or nylon float bags,just make sure to eliminate any sharp edges! Make a boat without shear clamps or, plane them down to what is needed. 1/2"x3/4"? then planed at an angle to take off another 3/8" at the inside edge. Make endpours minimal as necessary. Don't use glass tape (except for deck/hull butt seams) just slice up pieces of 4oz cloth, for boats with fillets, mask the width deemed necessary for the fillet before gooping the stuff in. In my opinion there's a balance that you can't get away from ,, If you weigh 175 lbs you need more boat material than a person that weighs 135lbs. and less than a person that weighs 215 lbs. My gut tells me if you use less wood you have a lighter weaker boat,if you use less glass/epoxy you have a lighter/weaker boat,and the converse is true, the trick is to decide where the boat needs to be made strong and where it isn't needed. These boats are used for classes and trips so my bias is to make things sturdy. Funny thing is that the boat still feels heavy at the end of the day and light at the beginning.

Messages In This Thread

3 mm vs 4 mm plywood?
Nathan -- 10/12/1999, 1:14 pm
Re: 3 mm vs 4 mm plywood?
lee -- 10/13/1999, 1:04 am
Re: dings
lee -- 10/13/1999, 11:20 am
it's a question of glass/epoxy lay-ups
Dean Trexel -- 10/12/1999, 5:29 pm
Overall weight of finished boat
Scotty -- 10/13/1999, 12:59 am
Re: 3 mm vs 4 mm plywood?
Mike Scarborough -- 10/12/1999, 4:12 pm