Re: First attempt at boat repair
Use TiteBond3 & you'll only need to leave them clamped for an hour or 2....
@4layer stringers, glue 2 layers together, and use modified WOG transom clamps & screws to hold them together. Do 1 set, & set it aside to dry. Do another set, set it aside. And do that twice more. You'll have 4 short sets of 2layer stringers.
@2layer stringers, glue 2 layers together, and use modified WOG transom clamps & screws to hold them together. Do 1 set, & set it aside to dry. Do another set, set it aside.
By now the 1st couple of sets of 4layer (that are each currently 2layers) should be cured. Once cured, glue 2 sets together to make a total of 2 4layer @3 1/2' stringer
If you have access to a decent table saw I'd make all the stringers slightly wider to allow you to trim them down to final size after you get them glued up into 2 or 4 layers.
Lookup a post by WoodOnGlass, the transom clamps are listed w/ his Deck, Stringer & Transom fabrication link...... Something similar but on a smaller scale can be used clamp your stringer pcs together.
The other choice is to get quite a few batteries, paint cans, lifting weights etc & use just enough screws to hold the parts together, stack them & weight them down all at once.
Your truck tire may sound like a good idea, but it is too much pressure, not well distributed. W/ TB3 you only need to securely clamp the parts together, too much pressure is as bad as not enough. The weigh of the truck may in fact warp the plywood as it cures, and squeeze some of the glue out of the joint....