Soft squeaky spot

[Dubo]

One of my ports had a leak that the PO didn't take care of which allow water to make its way into the deck core. I rebuilt the interior port wall after removing the rot where the port is. Now I would like to fix a soft spot on deck from this leak which I am reminded of every time I step on it. Is there a reason I can not attack this from inside the boat rather than cutting through the top of the deck? My plan was to make a beveled rectangular cut through the interior FG lining in the head. (see pic) This would give me access to the core from underneath rather than topside. My estimated cut is about 9" x 20". Once FG is cut out, I would remove whatever water damage there is and replace core with either marine plywood or starboard. Replacement would probably be sections since I want to remove as much old core as possible. Once the area is dried out, I would then epoxy the replacement material in place and then take the interior FG cutout and bond that with epoxy to the new core. Hopefully this can be done with minimal cosmetic issues since the beveled cut would help with fitting the cutout back in place.
Does this sound doable or is there a reason most people seem to do this repair topside? I assume the interior liner has no structural value.

Attached pic shows planned area of cutting.

TIA for any thoughts or words of caution.
Dubo

 

[geek_guy]

I too have a nice soft spot. I believe the main reason it's mostly done from the top is gravity. As in the epoxy will fall down into the crevice rather than wanting to drop down out of your dug out space.

 

[finefurn]

Had this same problem with the boat I just finished restoring. (CRI Ensenada 20) I Needed to replace a good third of the cabin ceiling due to a rotted plywood core. I chose to tackle it from the inside because the outside FG skin was much thicker than the interior skin, and it would be difficult to keep the correct curvature of the deck if I removed the outside skin. I also thought that I could cut out the interior skin and just epoxy it back in place, but the rot extended beyond the skin I cut out. I ended up layering several layers of FG cloth to build up a new skin to the thickness of the original. Long story short, Its a messy job but doable. Forget about saving the FG skin you cut out and epoxying it back on and not seeing the cut line, can't be done, you got gravity working against you. Think every last detailed step through and get everything laid out ahead of time. Pay attention to the tackiness of the epoxy and wear a full TYVEK suit with a full face shield