Stringer and floor replacement

[jpstude]

I'm replacing the center stringer and floor on a '66 18' Fiberform. It had a Mickey Mouse piece of 5/8" wood for a center stringer. I have decided to replace it with a 2"x12". I want to do that for hull strength. I will bull-nose the top edges so I can wrap it in glass. The other stringers and transom are good. I will only re-glass the other stringers in, after bull nosing them. I think I'll also install flotation, as they didn't put it in back then.
So, is the 2x12 too much overkill? Of course it'll get scribed and cut to fit. I'm also installing a 8' 4"x6" on each side of the engine mount stringers. Those, I'll stainless steel lag bolt and glass in. So, what do you guys think? Army tank?

 

[mrdjflores]

Re: Stringer and floor replacement

that would be a tank....

depending on how you build up a stringer, depends on where you want ot get the strength from. some people will use the pink rigid foam from your handy dandy home store as the stringer center and use many layers of glass on top of it. in this case, the foam is just acting as a form for the glass to lay up on, the strength of the stringer comes from the glass...but you have to use alot of glass. i have seen other people use 5/8 or 1/2 (x2) ply as the core of teh stringer and glass over them moderately. in this case, the strength of the stringer comes from a combination of the ply and the glass

others should chime in soon

 

[HVAC Cruiser]

Re: Stringer and floor replacement

Hi jpstude,
For the stringer I would use ply instead of dimensional lumber, it is more stable. I would go with 1 - 3/4" should be fine if you want overkill laminate 2 pieces together to give you the 1 1/2" although you really don't need it. For the motor mount stringers what is there now, are they 8' long? For my one project I used some microlam I had along with plywood used PL to put it together and glassed it in with 1708

 

[jpstude]

Re: Stringer and floor replacement

Thanks guys! All of the stringers are dimensional lumber. I guess I could use ply and stagger the seams for strength. I'm used to building commercial fishing boats where "there is no success like excess". The engine mount stringers are full length from the transom to the bow, so 8 footers will fall considerably short of the bow. I just figured I'd beef them up a bit. Even though it's only a 250 six, I thought it might be a good idea, after all, the wood in the stringers is 44 years old. Additionally, I'm going to run 2X's between the stringers at each seam of the flooring (every 4') so I get a little more strength as well as a better seal on them.