TOPIC: first deck rebuild

I have a 1978 mark twain 19' with I/O merc 165. I have completely gutted the floor, stringers and all down to the hull. Now I have fiber glassed before, and done a bunch of research. but i still have a few ?'s. can i make my own stringer system? i am thinking 2x4 and 2x8's does it have to sit on the bottom or can i like bridge it across the hull like a platform? with my idea the wood would be out of the water almost completely(yes i would still cover with FG). it just seems running it vertical from the bottom instead of horizontal would keep it directly in contact with the water. and i am wanting to limit that. i guess its hard to explain. And what is floatation foam for, doesnt a boat float either way.I know that may seem like a total noob ? but i am. first boat, first time in a boat first time driving a boat. i got it for cheap, and with a chevy 250 motor, i can work on all that as im a mechanic by trade. just worried about the deck. but props for knowing half the correct terms right

hpcma1,

First, WELCOME ABOARD.

Also, I see NO reason why a framework "up out of the water" wouldn't work in "OUR boats", as most of the 1950s and 1960s glass boats are HEAVIER/THICKER FG than more "modern" glass boats are. Otoh, the 1970s & beyond depend on the stringers to stiffen the bottom/sides.

What I've wondered is WHY the floatation isn't installed under the gunnels, as logically that is where the flotation SHOULD be.= a "swamped boat", with flotation foam under the sole is PROBABLY more stable "bottom up" than right side up.

Also, ImVho, you have THE "class" I/O set-up as the 160/165HP Chevy-based engine is thrifty on fuel, relatively powerful & long-lived.

yours, satx

Welcome aboard hpcma1,
Satx hit the nail right on the head, floation foam is for bottom up situations so it doesn't sink. As for the deck idea, IMHO stringers touching the hull is a good thing for strength. but Iwould go with 2x4 as the 2x8's are going to be really heavy! matt

matty83; hpcma1,

I've been thinking for some time that:
1. Floatation in the bilge is better for saving the BOAT than the PERSONS therein
and
2. stringers made of marine or MDO plywood, sealed with epoxy, will be both stronger and longer lasting than made of natural timbers.
(Plywood is to lumber as Velveeta is to cheese.)

yours, satx

The hull is reliant on the stringers mounted longitudinally for strength , they need to be there . "Bridging" the hull to keep the wood out of the water will compromise the structural integrity of the hull , not a good idea . Rebuild it like it was built . As for stringer material use Doug fir . If your concern is with rot remember how old your boat is and how long it took for those stringers to rot the first time . If installed correctly a new stringer/ floor will last thirty years maybe more .

ok so i guess if it is for hull support i should replace then as they were. see i know of house and cars, i was trying to use my flooring exp. in the boat lol. so now this has turned into a worrisome job. i am already worried about removing the drivers side console, whole lots wires, and some have no connectors. the guy i bought the boat from thought i was nuts. apparently its a big boat and project for a beginner. but i got it and the tandem axle trailer for 400 motor runs fine and had new 20 gal. fuel tank installed last yr. the floor only had 1 soft spot, but i wanted to try and do it right rather than just FG that one spot. while i have ur attention though. how the hell did they attach the seat backs to the bow, they were so rotten they just pulled off, and they were attached buy a nut behind the fiberglass. i have no way of getting my arm up there no extensions has been able to get up there. there are 5 seat cushions, could i cut a small hole that would be covered by the next seat cushion? also i called my local marine shop and he said epoxy resin not polyester, and not to use pourable foam, but rather rigid foam. due to the fact that 99.7% close cell wil turn into a sponge. which i noticed when i took old foam out it was soaked???

The best way to get the advice you need to complete your project is to get pictures up . Its a lot easier to see the issues .
The choice to use epoxy or polyester is up to you both will do the job just fine with epoxy being a lot more expensive than polyester .