Transom & Stringer Replacement

[I'll Go]

I sure could use some help. I have a 1982 V20 Steplift. I want to replace my stringers and transom and I can't decide if I want to go Composite, Treated Plywood with Fiberglass, ArJay or SeaCast. My other struggle is not being able to find out about the flotation. From what I can tell there is the "upper deck" that sits on the stringers and bulkheads then vast amounts of open area then the hull. So, how much floatation is actually in this boat? When I rebuilt my Chaparral it was relativity easy; remove the deck, remove all the old foam, fix the stringers then work backwards. I'm having a hard time figuring out the design - no one that I've talked to has prints for this boat and everything I've seen on YouTube looked a little different than what I have. Any help you can offer would be much appreciated -