16 yr old restoring a wooden boat..HELP!!!!

so i bought this peterborough cheap last summer in hope of restoring it, but the bottom is a little more rotted than i thought...my plan was to start on the outside by using "zip-strip" and a chisel to remove the paint and varnish, then sand it down thuroughly and add a few layers of urothane..then the rot was just on the bottom 2 planks..so if i bought green plywood i could curve it into place and screw it in somehow right?part of the strip of wood sticking out on the bottom(keel?) is missing too so i was going to do the same sort of thing...and i havent put much thought on the inside yet...does anyone have any suggestions? i was told it was made in 1930s..and the 2 wooden boat fanatics im related to, looked at it and never seen a model like it..ive been trying to research it since i bought it but was unssuccesful
some questions:
1-i believe the keel and gunwales are white oak, so i plan to replace the rotted portions with the same.theres about 3 ft length under the rotted keel thats also rotten(against the canvas)can i chisel out the rot and fill the gap with waterproof non-shrink wood filler, then place the new keel over it?or do i need to replace that "under-keel" strip?
2-the transom was previously replaces with pine plywood. its ugly, but ive been told not to mess with a working transom. would it make sense to glue some cedar veneer on the plywood?
3-I'm told that standard polyeurethane isnt truly watertight.what is a good, durable, clear finish?do i need shellack?
thanks for your time and help, Seth

 

You could use plywood to repair the garboard strakes, but you live in Vermont and you should have access to some cedar. Small knots would be okay if they are tight.
Save what you can of the rotted planks and use them to copy onto replacement boards. Match the thickness (probably 3/8" or so) and attempt to shape the edges to match the original bevels. A good tool to buy, available anywhere, is a bevel or bevel square as they call them now. With it you can transfer angles from old to new.
Take your time. It's worth it to do it right, and here you've got a lot of help along the way. One step at a time, and if you can upload some pictures, that would help alot.

 

ok thanks ill do that this weekend(i go to a 5 day/wk boarding school and the boat doesnt quite fit in my room)

 

OY..that's dedication...can't fit the boat into his room he says! Son...WELCOME ABOARD!!!!

 

haha thanks =D