Rebuilding '82 Crestliner

[csdisme]

Hello everyone,
I have an '82 fiberglass Crestliner that I came across and couldn't pass up. I knew it needed a new floor at minimum and a bit of engine work. I have helped on a couple of boats that needed a new floor so I jumped right in. The old floor came out easy, removed it from the transom to just under the front deck. I was somewhat surprised to see that the plywood that was used was only 1/2". Instead of using marine ply and glassing both sides, I found several 5'x10' solid 1/2" fiberglass sheets and thought I would try that instead. A friend of mine has a pontoon boat and thats what that floor is, so I figured I go with it.

My dilemma is, I am about to the point where I am going to make a template and I was cleaning up some of the edges where the old floor was glassed to the sides and I noticed the one of the stringers was not as tall as the other. I ran a straight edge across the beam and the port stringer comes just about to where the bottom of the new floor will be, but the starboard stringer is about 2" shorter. I would like to support the new floor across its width so there is no flex. The stringers are hollow fiberglass and are foam filled. My first instinct was to build up the starboard stringer so it was level with the port one and then go from there. But I have read where the floor in some boats in supported using foam.

My thought is to lay the floor panel in place and glass it around the perimeter then fill the space underneath with foam. I plan on putting an access panel in between the seats for some added storage, so I would be able to get the foam in pretty easily working through the hole for the access panel.

I attached a couple of pictures, the red outline is the access panel opening, it will be 13"x40". The yellow is where I thought i would put the foam and let it expand out over the stringer once the floor is in place. The other picture shows the gap I'm talking about.

Any serious issues with doing it this way? If so, what are some alternatives?
Thanks in advance for any suggestions and comments, I appreciate it.

Cullen

 

[alldodge]

There would be no issue with filling with foam and would add strength. I would not use FG sheet instead of plywood, I don't think it will be as stiff.

In most cases its best to use a whole saw and cut holes in several places to pour foam in. This also allows for it to expand and come out showing there was a full pour. Also need to place weight on the deck so the foam does not break the deck away from the hull during expansion.

This is mine after the pour, note the foam holes. The boxes have steel in them

 

[alldodge]

Do check the stringers for moisture using a 1/4 inch drill into the sides in a few places.

 

[csdisme]

Thank you much for both of your replies.

I will have to check with the supplier of the fiberglass panels. When I was there looking at them they had one on a pallet with about 3' over each edge. I stepped on it and it flexed about halfway from the pallet to the ground. It weighs about 3 times what a comparable plywood panel does, and I cant lift it by myself. I'm going to give it a try as the price for a 1/2" 5' x 10' panel was $60 and I figure the amount of time and money I'll save by not having to epoxy both sides is worth trying it out.

After a bit more trimming and scraping I noticed that my first assessment of the problem was incorrect. I had the edge of the tube above where the panel is supposed to lay. I have added a couple of pictures to explain what I'm seeing.

The floor was rotted out so badly, I did not realize there was basically a "shelf" (red line in second pic) for the floor panel to rest on at the sides of the hull. When I put the tube where it should go, I noticed there is a gap between the tube and the shelf of about an 1" on the port side. What really threw me off was the first picture where the piece of 1/2" ply in the bow looks like it fits correctly, but when I looked closer there is a gap on the port side. My initial fear was that the boat had torqued or twisted without the floor throwing everything off. I decided to measure the height of the stringers and found that the port stringer is about an 1 1/8" taller than the starboard stringer. I cannot figure how a boat builder could have done that.

The stringers are foam filled, I found several holes in the top to allow the foam to expand out. I would like the new floor to lay in the position it is supposed to. My question is, if I were to cut the top of the starboard stringer off and trim it down to the proper height, would I be causing and structural issues? I could then replace the top using the heavy woven mat that the factory used, drill a couple of expansion holes and refill it with foam.

Like I mentioned in my original post, I have helped on a couple of these projects, but I wasn't the decision maker, and none of them had any issues. But I am curious if anyone had run into anything like this and if so what their resolution was.

Thanks again and I appreciate the insight.
Cullen