Part floor repair opinions

Good day

I have an older 1988 Mirage and am having the interior done in it. After removing the rear seat and starting to clean up under it I found an issue once I removed the small square fuel sender access cover.

I do not have any pictures but at the very rear of the floor before where it stops to enter the bilge there is a square cut back (3 sides open to the bilge) on top of the fuel tank for sender access. The expossed wood under the molded cockpit insert was sealed but the edge towards the front of the boat must have wore away causing water intrusion to rot the wood under the cockpit insert. The other 2 sides seem solid and not wet. Hopefully it has not spread too far forward.

I was thinking about doing a spot repair on that area of wood mind you I am unsure how far it has spread yet and it is on top of the fuel tank I suspect. I dig out some of it with my hand and it goes forward at least my hand length.

My plan is to do a few small hole core drills with maybe 1/8 to see if I can determine how far it has gone. Then using a thin rotary blade attempt to slice a larger square through the cockpit cover layer and seperate from the floor with minimal cut into the floor. Cut and remove the rot back to decent wood and add a new piece into the section. Glass resin the removed cover back down to the replaced section.

My question what is the best way to replace the piece structurely as I can not get under it do to the fuel tank and using cloth above would not allow the cockpit cover to replace level, can the new piece be adhered in somehow to the edges of the floor left in or reduce the new piece width and glass over top?

Thanks
Mat

Re: Part floor repair opinions

Can you get to the underside a couple of inches away and around the repair spot? If you can put some wood or aluminum strips under the edges. screw them up under the floor around the edges making a platform to set your repair wood on and screw the repair piece down.

Re: Part floor repair opinions

Thanks for the reply

I have not cut and pulled the cover out yet but I would doubt it. It has 100 gal fuel tank in it and by the looks of it it is directly above the tank with little to no clearance, which probably explains why there appears to be no give in it.

Would it hurt to use the tank as the support, make sure the new piece sits right on the Alum tank?

Re: Part floor repair opinions

I would never use the tank for support, but that's just me.

Re: Part floor repair opinions

It sure does not sound like the most optimal.

Any thoughts on 45 cutting the mating edges and glassing to that joint, hopefully when I get into a little some bright idea will come to me. Since the area is directly under the rear seat where storage is it is not a load bearing surface, I am hoping I caught it before it got too far.

Mat

Re: Part floor repair opinions

45 degree cutting sounds like a good idea.

Re: Part floor repair opinions

A 45* bevel and some PL adhesive, weight it down until the adhesive cures and then glass it in tying back into the old glass.

Re: Part floor repair opinions

Okyay guys now I am a tad confused. I have only dealt with Ply floors before and this molded floor has me a little baffled.

I went out and did a few core drills to see what I was looking at as the rear part of the under ply was pretty wet which makes sence most water would drain there and get trapped by the fuel tank.

When I was taking the samples I was expecting to see a thin glass molded floor section with a thick ply wood under floor.

What I found was a very thick molded floor section, it has the anti slip pattern in it, with a very thin ply back which seemed okay but very hard to tell due to the very little ply shavings I could get before I hit the top of the fuel cell.

The amount of ply under this thing is very thin, I think it would be hard pressed to be .25 inch, the molded floor is .5 or more in glass thickness.

I doubt the ply does anything for the structure, can someone tell me how these molded floors are put in and the purpose of the ply, is it just for the molding process, or some other purpose?

I doubt I could even seperate the ply layer I would have to cut that section of the molded floor out which sems like a bad idea.

Mat

Re: Part floor repair opinions

Is the rotten/wet spot soft under foot?

It sounds like you have maybe 1/4" plywood under there and it was probably just put in as a base to hold the glass and resin until in cured, I'm not sure about this... but it's the mental pic I drew from your description.

The thing that would bother me is, how much water has been getting in? and for how long? and what has it done to the below deck structural members and foam?

Re: Part floor repair opinions

There is no soft spots under foot.

The ply is maybe 1/4 could be even less and it does seem as though it is used for molding process.

The boat is a 1988 and I am sure there is some water under the structure not sure to what extent.

Stringers are encapsulated mind you that does not mean much at the rear but from what I see if anything the motor boxes would be the first to go. I am unsure about the foam, I thought these models did not use foam in them? If so there cant be much room for much as there is a lo of tank under there. The survey that is due will tell me a little about the rear as he has a moisture meter.

I read somewhere these were a very high end built hull, molded cockpit, blah blah.

Not really sure where to go with this but I am now interested in the manufacture of this thing and the actual structure under the floor area. Any idea other than forums where to get some info?

Mat