What is this black stuff?

[davidpm168]

We have a leek in a 1987 Catalina 27'. We started grinding and this picture shows an area at the very top of the keel on the starboard side about in the middle of the boat. This boat has a glass skeg keel of about 12? with the lead keel affixed to the bottom of that. The lead glass joint looks good. This picture is taken from the center of the glass skeg on the starboard side about in the middle. From the bottom looking up the picture clearly shows:
1. Red bottom paint
2. Gel coat,
3. Large Dark green band (very hard)
4. Small White band (Caulk like but rather soft)
5. Large Black band (Like putty very, very soft)
6. Tan, Pink (Very Hard)
It looks to me like #6 is good glass.
What is #5 it is worthless?
What is #4 it is not much better?
What is the #3 layer
The two layers of softer material white and black (about 1/8?) is between the solid dark green layer and the tan pink layer #6 from the shaft log to as far as we have ground, which is now mid keel.
Also about half of the #6 layer is spider cracked and crumbling and we ground through the hull.
This boat was grounded before by the previous owner and repaired by the yard in an area of about 6? by 24? primarily with bondo directly behind the keel.

 

[davidpm168]

Re: What is this black stuff?

This shot is from the starboard stern side. A couple of inches out of frame to the left is the engine saltwater intake. The first shot it at the same elevation (just at the point where the bilge of the boat curves down to the skeg) about 6" to 12" to the right.
I just never expected so many colors and don?t know what they mean. The black spots under the hole are solid so the blackness itself may not be evidence of rot.
This location is a few inches forward of the engine water intake. It was covered with the soft black layer and had soft glass underneath so it had to be ground out.
Some of the black layer is hard Some is hard and over solid glass, some is soft over solid glass and some is soft over delaminated glass.
I'm leaning towards the theory that it was repaired more than once. That would explain the normal glass at the deepest layer and the blue glass near the surface. Still don?t know what the black layer is.
My current theory is that the black part is a layer of a prior repair that went wrong. Maybe the glass that got too hot. Some kind of patch material improperly applied or cured. I can't imagine what happened exactly as I have not seen a layer that looks like this before.

 

[DJ]

Re: What is this black stuff?

What is the consistancy of it? Can you scrape it out?

 

[oops!]

Re: What is this black stuff?

hey dave welcome to i boats!
merry christmas!

sa dj suggested what is the consistancy?

could it be a rotten area in the glass?

keep us informed

 

[davidpm168]

Re: What is this black stuff?

Yes some of the black stuff will scrape off, some peel off in good size slabs. Some however seems to rather hard. I'm thinking glass that got overheated during cure but I have never seen it before so don't know.
Can I assume that you guys have never seen glass this color before.
The white pink Is what I think is a normal color. The dark geen maybe.
Never expected to see every color in the rainbow within the layers of glass.

 

[ondarvr]

Re: What is this black stuff?

Those keels can have a great deal of fairing done on them when new, and then if it was repaired again, there's no telling what it might be. It's kind of up to you where you want to stop grinding, but it's best to remove any questionable material.

 

[DJ]

Re: What is this black stuff?

Those keels can have a great deal of fairing done on them when new, and then if it was repaired again, there's no telling what it might be. It's kind of up to you where you want to stop grinding, but it's best to remove any questionable material.

I completely agree. The amount of time that passed between layers is an unknown. It could be different materials, different operators or a combination of the two.

If it is not held fast to the other parts than it needs to come out to get a good bond with any new material.

 

[oops!]

Re: What is this black stuff?

the black stuff i found in my boat, very hard, waxy type stuff. was confirmed to be a flo coat. it can be used in repairs.
i dont know if that is what your looking at but a possibility

oops