[steven_p]

Bear with me, this is my first fiberglass project. Thankfully it's in an area that will never be seen unless you're underwater

The swim platform on our boat was badly water logged so I cut the bottom layer of fiberglass out so I could remove the wood core. I was expecting to uncover a piece of marine plywood but instead it was many small blocks (1"x3"x1/2" thick) glued together like a butcher block.

I was planning on using 1/2" marine grade plywood as a replacement core, but I have to wonder why they used the butcher block approach instead of plywood. My only thought was that it would cure flat with the resin, and that plywood might warp as the resin cures?

The swim platform is about 9' long. Should I install one solid piece of plywood as planned? Or should I cut the plywood into strips? Any other ideas?

Here's a picture of what it looks like with core removed:

[steven_p]

From what I've read tonight the old wood core was balsa. There appears to be no advantage to balsa over plywood except for weight, and weight is not a concern in my application. Not to mention a balsa core is also more expensive than marine plywood.

It sounds like a single piece of ply is the way to go. I'm hoping that if I coat both sides in resin/glass mat, the expansion will be equal on both sides thus preventing any warpage.

Again, I'm new to fiberglass repairs and I apologize if this question has already been asked a million times.

[oops!]

hi.....welcome to i boats.....

chances are there is a slight curve to the platform.........thats why the blocks.


as far as your intended method.....yep!.....go for it.

make sure the wood is good and dry.....(let it sit for a week with a fan and a heater on it.

and if you use poly resin, use the chopped strand matt next to the wood).

if you read about how to do a transom......the process is almost identical.

cheers
oops