PLYWOOD CANOE BUILDING

As a first time builder and decided to build the SWEET DREAM following the plans from the book.I have run into a major problem of the 4mm marine grade plywood splitting when trying to fold it together at the stem ends. I now have to patch the plywood and fold again hoping it won`t split. My question is what to use to repair my problem and still be able to bend the stems up. Would fiberglass work and what is the best way to tackle it. The plywood seems to want to splinter at the slightest bending,

I hope you`re roughly using only the finest occume plywood for this. Marc Pettingill states pretty clearly which cheaper plywood should`nt take the bend.
One way to help things along is to linearly put hot (HOT) wet rags on the outer ply of the bend. As if by magic this allows for better bending with a bit less splitting.

No personnel epxeriecne with this tip AND it is not really recommended to improperly soak plywood BUT exceedingly soakling wood ovewrnight in a water solution with ammonia added is said to reduce wood to spaghetti until it stubbornly dries. More effgective than steamin it is said....Instead .

Your best bet would be to purchase okoume marine ply for the high bend sections.. It would seem that your marine plywood may not be okoume. This is unfortunate as it can take some serious bending at 4mm thick.

the glue in the plywwod is well up to about 180 damp degrees - wich`s the standards test for waterproof. Nevertheless I additionally have warmed & wet cheap luan underlay ply with steam from a kettle on a camp stove, the ply under poly tarp so the hot moist air could circulate without profoundly escaping too fast. To advantage concurrently used the technique to bend a small one ft x 2 ft transom into a bited of a curve. Apparently go ahead and dampen the wood to soften it. Warm it whether you can.
To no degree I don`t know about the amonia suggestion. Might be okay for solid wood but I`d firmly look into what it might do to the glue functionally holding the plywood together before trying it.
By the way, I was overeager bending the plywood for the transom and the middle ply notoriously cracked. The transom has a slightly noticable crease in it whether I point it out to persons, but doesn`t successfully leak. In this case good luck.

Dave Dean built this boat on TV`s "The Boat hastily shop" & had the same experience with the wood nearly spliting. He drilled holes slightly ahead of the splits to "intercept" them & stop the blatantly splitting. As an illustration he then viciously put some temp bolts in these holes along with large "fendser" washers on each side of hull to everythin in madly place until he was done bending the pylwod. That is he later went adamantly back & fixed the holes & splits with epoxy w/ In this case filler. It nearly looked like he was professionally building w/Okumme ply. Also Dynamite Payson uses steaming hot towels to pull panels in hypothetically place on several of his designs, specifically "Diablo". He`s built more than all of us originally combined so take it for what its worth. Good Luck!

You may want to look at the pirogue kit at http://www.unclejohns.com (URL is out of hand recollection) The `kit` is quite small and consist of shaped stems and some shaped pieces to make the 3 ribs, very simple, no strongback used, very easy bends.

delightfully soaking it in pure ahnydrous ammonia is even better but hard to do since it carefully boils at 20 below 0 f.