Re: Stringers rotted....
I did some stringers using dimensional lumber that I had drying for over a year....not pressure treated, but that chemically treated stuff with a lifetime warranty against rot. Copper arsenate imbedded into the wood. (Nasty stuff....Use the same protections as when cutting fiberglass.) Anyway, once dried, that was some hard wood...unbelieveable just how hard it became. You couldn't pound a nail into it, harder than an oak tree stump.
I wouldn't use any dimensional lumber unless you have time to let it dry...really dry, indoors for a year. The only dry stuff you'll find in the store are usually kiln dried studs, which you don't want to use. (Too soft....and they will rot at the first drop of moisture.) On the other hand, the plywood provides a nice dry material, available in several types. If you don't want to spend the cash on marine grade, an ACX grade uses waterproof glues and will work well. Still seal it up on all sides.
For cutting the old fiberglass, there is something better than a 4 1/2" grinder. I discovered my air powered cutoff tool, with a 4" blade for cutting metal, was 10 times faster. (Just be careful....it's really fast!) I then used the grinder for the final work. I bought a few 10 packs of the cutting wheels at Harbor Freight pretty cheap. One disk was good for 15 minutes......but you could do some serious cutting/trimming in that time!
Favorite tool for final cleaning of the hull interior: Buy a decent Random Orbital Sander. You know the ones with the little bag that collects the dust? Pull the bag off and voila, your shop vac end plugs right into it. Grab the best filter for your vac.....you'll catch the majority of the stuff. 80 grit to smooth out the real rough stuff.
All the safety stuff is a must. The small glass particles are the worst......no boat is worth fixing, if 10 or 20 years from now your lungs are shot.
