Fiberglass/wood repair techniques?

[blinkerfluid]

We're about to start a pretty major refit on our new-to-us boat and one of the big items on the list is to replace the holding tank (it's aluminum).

Replacement of the tank on our boat will require cutting the floor, which I *think* is composed of fiberglass over a 1/2" plywood core (based on some low resolution photos I've seen of sister boats).

Cutting the floor out is pretty straightforward, but I'm not sure what the best way to reinstall it is. If I had access to both sides, I'd probably taper the edges of the cut, epoxy in a new piece of wood, then glass over the top.

Only thing I could think of is installing a flange on the underside of the floor for the piece I cut out to sit on when installing. If I did that, I could potentially just bolt the floor to the flange so it'd be a large access hatch. There's a 2nd piece of plywood with a teak veneer that goes over the fiberglass floor, so aesthetics won't be compromised. Only concern might be the loss of any structural integrity the floor provides.

So, Any tips/techniques for replacing a cut in the floor with only one sided access?

[Chotu]

Originally Posted by blinkerfluid

We're about to start a pretty major refit on our new-to-us boat and one of the big items on the list is to replace the holding tank (it's aluminum).

Replacement of the tank on our boat will require cutting the floor, which I *think* is composed of fiberglass over a 1/2" plywood core (based on some low resolution photos I've seen of sister boats).

Cutting the floor out is pretty straightforward, but I'm not sure what the best way to reinstall it is. If I had access to both sides, I'd probably taper the edges of the cut, epoxy in a new piece of wood, then glass over the top.

Only thing I could think of is installing a flange on the underside of the floor for the piece I cut out to sit on when installing. If I did that, I could potentially just bolt the floor to the flange so it'd be a large access hatch. There's a 2nd piece of plywood with a teak veneer that goes over the fiberglass floor, so aesthetics won't be compromised. Only concern might be the loss of any structural integrity the floor provides.

So, Any tips/techniques for replacing a cut in the floor with only one sided access?

You’ve got it. That flange is what you should be doing. As long as the floor is not in some way structural to your boat, The flange will allow you to drop it into place and glass the top. Also, the idea of bolting it and having a large access hatch is even better.

I think you don’t have many answers because you have answered the question already. LOL. These are good ideas.

[mike d.]

What Chotu said ! I can imagine who had the shortsightedness of covering a tank, with a sub floor, and floor so you had to do that kind of demo to get at the tanks ! When you get at it think about how to get at the tanks with out structural demo !

[blinkerfluid]

Thanks to both of you, glad to hear I'm on the right track.

I wish it was just a matter of the 2 layers of flooring I had to contend with.. half of the tank is also under the fwd berth. So half of the floor cut I'm going to have to make is going to be underneath the berth structure.

[coopec43]

You don't say the design of the boat but I don't think the floor would be structural. If it isn't I suggest you make it a removable panel for safety reasons (in case of a leak). Of course it would have to be held in place by clips in the event you went ass over kettle.

I could think of nothing worse than knowing you have a leak somewhere and not being able to do anything about it. (All my floor boards and the bottom of lockers are removable)

[Uncle Bob]

Originally Posted by blinkerfluid

We're about to start a pretty major refit on our new-to-us boat and one of the big items on the list is to replace the holding tank (it's aluminum).

Replacement of the tank on our boat will require cutting the floor, which I *think* is composed of fiberglass over a 1/2" plywood core (based on some low resolution photos I've seen of sister boats).

Cutting the floor out is pretty straightforward, but I'm not sure what the best way to reinstall it is. If I had access to both sides, I'd probably taper the edges of the cut, epoxy in a new piece of wood, then glass over the top.

Only thing I could think of is installing a flange on the underside of the floor for the piece I cut out to sit on when installing. If I did that, I could potentially just bolt the floor to the flange so it'd be a large access hatch. There's a 2nd piece of plywood with a teak veneer that goes over the fiberglass floor, so aesthetics won't be compromised. Only concern might be the loss of any structural integrity the floor provides.

So, Any tips/techniques for replacing a cut in the floor with only one sided access?

I reckon that you have it covered (pun intended), just make it so it is removable in order to eliminate any need to remove it ever again.