cabinside core

[Redbeard33]

I am replacing the ports on my H33C with NFM trimatrix, my question is once I fill and prep the opening for the new port i will have to re-drill through the outer skin exposing plywood core again. Is there a way to seal the inside of the new fastener holes without over-drilling/filling/re-drilling to protect the core? I would like to avoid having to do that hundreds of times. Also along the whole inner edge the core is exposed, is there anything beyond just painting it with epoxy to protect it? I was thinking of wrapping the edge in a thin glass tape. I will try to get better pictures soon.

 

[walmsleyc]

I did a full port replacement recently (lots of rot and water in the core). I used a router and a bit like this to remove the plywood core to a depth of about 1/2". Using a small epoxy brush, I reached in a sealed the plywood core with epoxy, and then filled the space with thickened epoxy. The mounting bolt holes then passed through only fiberglass and/or epoxy. Any future leak should not be able to find a way to the core.

Bot sure if that's faster that doing each hole individually, but it certainly eliminates places where water can get to the core.

Chris

 

[Redbeard33]

That idea crossed my mind but i was unsure, I'm glad to hear it worked out. How did you get the entire core thickness? Was it a stacked "dado" type arrangement or did you adjust the collar and do it in two passes?

 

[walmsleyc]

At each window I checked and re-checked the depth settings on the router primarily because the thickness of the outer layer of glass/gelcoat on the cabin was not consistent. Sometimes, the forward and aft end of the opening had significant enough differences that I had to take account of. Anyway ..

- First pass, adjust router depth to remove mostly wood, but just a touch of glass on the outer skin. Give the epoxy something clean to bond to.
- Make a second pass to do the same for the inner layer of glass
- I don't think I ever needed a third pass.
- The core space was inconsistent either due to different thicknesses of plywood used, or because the wood core has rotted/de-laminated and allowed the skin, and inner glass layer to separate.

Your cabin sides need to be reasonably flat around the windows without any fittings or other obstructions. A little curve shouldn't be a problem. Taking off a little extra glass shouldn't be a problem because with the addition of epoxy, you easily exceed the original bond strength of the glass to the wood core etc. The increase in strength around my windows was enormous. Before repair (windows removed), I would grab the opening and flex things a little bit in or out. Afterwards, I couldn't budge anything. That's good, because a reduction in flex should extend the life of the window sealant.

Cheers
Chris

 

[jorgefife]

At each window I checked and re-checked the depth settings on the router primarily because the thickness of the outer layer of glass/gelcoat on the cabin was not consistent. Sometimes, the forward and aft end of the opening had significant enough differences that I had to take account of. Anyway ..

- First pass, adjust router depth to remove mostly wood, but just a touch of glass on the outer skin. Give the epoxy something clean to bond to.
- Make a second pass to do the same for the inner layer of glass
- I don't think I ever needed a third pass.
- The core space was inconsistent either due to different thicknesses of plywood used, or because the wood core has rotted/de-laminated and allowed the skin, and inner glass layer to separate.

Your cabin sides need to be reasonably flat around the windows without any fittings or other obstructions. A little curve shouldn't be a problem. Taking off a little extra glass shouldn't be a problem because with the addition of epoxy, you easily exceed the original bond strength of the glass to the wood core etc. The increase in strength around my windows was enormous. Before repair (windows removed), I would grab the opening and flex things a little bit in or out. Afterwards, I couldn't budge anything. That's good, because a reduction in flex should extend the life of the window sealant.

Cheers
Chris

These were good exchanges, and as I one day intend replacing some ports, it was indeed good information(I have the same boat as Redbeard)
Thank you both
And good luck with your modifications: take lots of pictures for dummies like myself!

 

[Redbeard33]

thanks chris, no matter how much foresight one may have its always nice to get an explanation for someone who has tackled the same project before. Thats whats great about this forum, I'll be sure to bring my digital camera and take plenty of pics. for the owners mods section.