Brown spot bleeding through paint in cabin ceiling

[OLDSON]

Don't know where's it coming from. Spots were painted over and then bled through. Construction of hull is fiberglass sandwich with balsa core in middle. Boat is a 1970 Buchan, maybe it's from rusty fasteners from wooden frame? Did these boats have a wooden frame that they laid fiberglass on? Or were these mold boats?

[atoll]

sometimes staples were used to hold cflex or matting in place using airex or balse core

[Blackie Swart]

Hi Oldson
I have found that when there are water leaks coming through fittings, cracks etc, the water is brown from it going through the Balsa - the balsa even rotting a bit. It also seems to travel - that is the leak may be in another area altogether but comes through in the brown areas. Anyway, that was the case with my boat.
Cheers.

[MarkSF]

That was my first thought... that there's a leak into the core, and it's finding it's way out where your brown stains are.... not good at all

[DeepFrz]

I'm afraid that you are seeing the signs of a rotting core. You will have to start checking for soft spots on the cabin roof and on your deck. Any fastener that goes directly into or through the core without an epoxy annulus will/can cause that.

[OLDSON]

I had a funny feeling about that. It's probably from some fasteners on the slider for the hatch for the companionway. I am doing a full on assault on my wet core this summer. I will post pictures. Is there any new threads with people doing this? It looks like I will be investing in a lot of fiberglass. There are a few soft spots on the boat which obviously need to be recored and then there are some spots that make crunching noises under your feet, like the fiberglass seats in the cockpit, I am hoping I can just sand those down to the fiberglass and add more layers to thicken it up and make it stronger?