Tricky (?) centerboard cabinet repair advice needed

Please excuse me if this isn't an appropriate post here. I'm new to this site and it looks like the place with the experience I need, but I may be way off.

I have a 70s era Mutineer 15' with a slow leak on the aft end of the centerboard cabinet. I pulled the centerboard cabinet cover off and, when I looked inside, I saw what you see in the photo I've attached. The view is looking downward into the centerboard cabinet. It looks like a mass of grungy fiberglass mat that is somewhat rotten. I can rip some of it up with my hands and, if I could get in there, I could probably rip up even more. This is about where I think the leak is. My questions are:

1. Does this look like a poorly-attempted earlier patch job that I'll need to re-do?
2. Is this the original fiberglass that has rotted out (seems unlikely)?
3. In this tight and weirdly-shaped space, how would you recommend I approach sealing this area?

Thanks, in advance, for any help you can give.

 

Welcome Tom

Tricky indeed.
Unfortunately, your pic is too dark for me to see inside of box.

It appears your vessel has a liner pan. If so increases difficulty.

Does the outer hull project up into the cabinet?

 

Blueknarr,
Thanks for you interest. First, yes, outer hull projects up into the cabinet. You can see this in the new images I've added.

I have added some photoshopped images where I lightened and annotated the problem spots. When you say 'liner pan' do you mean the coarse mesh fiberglass shown in the images? If you look at the annotated images you'll see that there's an abrupt edge to the coarse mesh material, like it overlays a smoother, cleaner, and darker fiberglass material. I can almost peel up the coarser stuff at this edge, as if it has lost some of its bond to the material below. I was wondering if this may have been a repair job (the coarse mesh material). I think my leak is somewhere under this coarse stuff, just aft of the centerboard cabinet. I don't think I can get a grinder down there to get rid of the funky material. I was wondering if there are any sealants that I just pour or paint over this to get a temporary seal. Coming at it from the underside of the hull would mean cutting out a very odd shaped portion of the hull for a big fiberglass repair. You can click on the image thumbnails to get a larger view.

 

I brain darted and didn't realize it is a dinghy involved. Larger boats may have separate deck and interior constructs. If they are separate, then the interior piece is called a lining pan. There can also be an overhead liner. So you have a deck and cockpit liner combined into one piece.

As you can imagine, it is impossible to make the hull interior and cockpit bottom mate perfectly. Often the gap is somewhat filled with flop out of a caulking tube. Sometimes, sheets of CSM are used as the bonding medium.

It appears that CSM was used in your hull. Unfortunately, the pieces did not mate well enough
I don't see evidence of an earlier repair. Just faulty original pore craftsmanship.

It would be best if as much as possible of the less than effective glass was removed. I know it will be slow and awkward difficult, but worth the effort. The bond strength with the new sealant is dependent on how clean you can get the surface.

One of my die grinders has a one foot extension. Perhaps .You could find a similar tool. Otherwise, coarse sandpaper on the end of a stick is always an option.

I would brush neat epoxy on/into the cleaned questionable surface.

I'll post a picture of my grinder extension when I get to the shop tomorrow.

Paul

 

I wouldn't think you'd cut out anything, just grind the bad area and repair. You should be able to tell where the leak is coming from by looking at it from the outside and probably make a much better repair by doing it from the outside. Patching it on the inside won't solve the problem of water getting into the laminate.

Looking at the pics and the shower stall type chop gun construction, I thought I'd invented a new word but the urban dictionary had it covered...

I think I got glass splinters just looking at the pics.

There was a leak on the shaft log of a large boat and nobody could find the source. It was fairly hard to reach so the repair was rudimentary sanding of an area that was sure to contain the leak. 5200 was then putty knifed on maybe 1/2 - 1" thick. That stopped the leak and after the 5200 sat overnite and hardened up a little it was covered up with a few layers of mat to do I'm not sure what, I think mainly it made the pile of 5200 look a little better and was paintable. It stopped the inside leak good but it didn't stop the water from having access to the inner laminate. The boat was eventually hauled and the leak fixed from the outside also.