mystery floor surgery on Trillium 4500

[Steve Hague]

Purchased our 1979 Trillium 4500 Gaucho one month ago and well into renovation. Windows out and damaged plywood frames removed. Floor plywood intact except for curbside rear corner, which has been excised.
Fiberglass floor running along kitchenette has been cut and then screwed down. Plywood underneath seems solid to probing and appears intact. I plan to grind down fiberglass along the cut, then lay in new fiberglass woven to patch.
I'm curious why this cut was done and if I might be missing something. Of note, I have pulled out the fridge, which is probably larger than the original since the opening has been enlarged and it is still a tight fit.
Any thoughts about why this cut was made?

[John in Michigan]

The "cut" or gap in the Trillium 4500 fiberglass floor along the front of the kitchenette is actually original factory. Its not actually a cut. Its the result of the fact that the interior fiberglass benches, cabinets, walls and floor were all pre-formed into several components before installing inside the camper outer shell. The "cut" in the floor is actually a seam between two of those pre-formed components. My 4500 has exactly the same seam.

[Steve Hague]

Thanks John, that's a relief.
Still thinking of doing the "repair", just seems it would be better to have that sealed some way. Since I will already be doing fiberglass lamination over the plywood replacement under the dinette bench, it would be easy to do this at the same time.
Does that make sense or totally unnecessary.

[John in Michigan]

The floor seam in my 4500 has the same screws stuck into it. Here is another thread where someone asked the same question. As you can see in these photos, some type of filler (maybe gelcoat?) was applied. This appears to be the case in my 4500 as well.

https://www.fiberglassrv.com/forums/...elp-69354.html

[John in Michigan]

Not necessary to fiberglass over the seam, but it would serve a purpose if this is to be the finished, exposed floor.

The plywood flooring inside all of my benches appears to be firmly attached to the bottom of the outer FG shell using polyester resin, then the plywood flooring has a thick coating of pigmented polyester resin on it.

Unusually, the plywood flooring under the front bench has been bent at a ninety degree angle in order to continue 6 to 8 inches up the front wall of the trailer.

[Steve Hague]

It doesn't look like they took any extra effort to conceal this seam in our trailer, other than laying carpet over it. Guess I'll proceed with laying in fiberglass and a brush-on gelcoat. Its a wonder that the plywood underlayment has survived 40 years with the open seam right below the sink.
Thank you for solving my mystery and giving me confidence to proceed.

[Steve Hague]

This is what it looks like under our dinette bench, before and after plywood removal.

[John in Michigan]

That looks familiar. Its the curbside dinette bench looking forward. Looks OK. I would attach the new plywood to the shell bottom using epoxy or waterproof construction adhesive and heavy weights. In the 4500, there are 8 body to frame bolts, 4 in the front bench, and 2 in each rear bench. I replaced all of them with 3/8" stainless hex head bolts and nylock nuts. I used large square washers to spread the load.

[Steve Hague]

Sounds like a good plan. I'm making a template to cut the plywood this afternoon.