Cabin roof/deck repair

[HotChocolate]

Hi all,
This is my first post here.
I have a 1978 catalina 22 which is in need of some repair work
On the cabin roof, between the poptop and the front edge of the cabin.
Over the summer I notice some flex on the cabin roof when raising the mast. There is also flex when you push up onto the ceiling of the cabin forward of the mast post.
With the repair of this issue in mind I began removing all of the deck fittings today so the through holes could be visually inspected for signs of water ingress as well as to re-bed all deck fittings.
What I found regarding the deck fittings around the area of flex in the cabin roof has left me puzzled. After probing around in all of the thru holes for the turning blocks etc, the timber samples I got back didn't appear to have suffered any rot. I checked around this part of the deck by tapping and found that it all sounded solid around all of the fittings as well as the mast foot, while the hollow/ flexing area is up to 100 mm from any fittings.
I had initially thought that I would remove the top side of the cabin roof around the non-skid area and replace the timber in this area in total. Now I'm not so sure.
Can anybody suggest what the best approach should be.
I'm open to all suggested solutions for this repair.

Regards,
Nicholas.

 

[caguy]

Is your compression post tight?

 

[HotChocolate]

Hi Frank,
yes the compression post is tight. the boat is very sound with this one issue.

Regards,
Nicholas.

 

[caguy]

I posted a few years ago about some water based epoxy. The stuff is really thin and flows like water. The capillary action of the porous wood draws the epoxy in and soaks it up. It then hardens in few hours. I used it on the rotted out floor boards in my Model A and it worked great. It is available at the Lowes paint dept.

 

[HotChocolate]

What was the technique you used to deliver the epoxy into the core of the floor? I am guessing a whole grid of holes on the upper surface?

 

[caguy]

A large paint brush.

 

[HotChocolate]

Well I've established there is no rot in the core material. What got me investigating the deck issue in the first place are a couple of cracks in the non slip part of the deck 100 mm behind the mast foot, running across the beam of the boat. This is where the flex in the deck skin is happening at its most severe. Today I cut a small inspection hole into the deck ( 25mm Dia) over one of the cracks, with a hole saw. I was surprised to see that the ply core, what I could see of it was in perfect order, it appears that the core only extends from the front edge of the cabin to about 100 mm back from the mast foot toward the pop top.This is a bit of a game changer. I am now back to square one regarding what to do with the void between the inner and outer fiberglass skins of the cabin.
I was thinking that the void could be filled with a thickened epoxy and the de-lamination of the inner skin could be repaired using the technique described on the West systems website, ie injecting slightly thickened epoxy into a matrix of holes around the are of de-lamination.
Any comments or advice on this plan of attack.