What is this black stuff? - Page 2 - SailNet Community
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post #11 of 14 Old 12-26-2007
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The bottom of the keel stub of the C27 consists of a plywood board, and the keel is through-bolted to that board. The plywood is encased in fiberglass, but occasionally the seal can get broken, such as in a hard grounding, admitting water, and causing the plywood to deteriorate. The plywood can be replaced, and it can be done by the DIY'er. Catalina used to have an instruction sheet, that shows how to do the job, if in fact it needs to be done. I suggest you contact Catalina, show them your photos and ask their advice.
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post #12 of 14 Old 12-26-2007
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Like Sailormon6 says, the keel construction is (from the bottom up) lead keel, 5200 sealant/adhesive, fiberglass, plywood and then fiberglass that is visible from the bilge. I have the aforementioned sheet from Catalina that shows the keel stub construction. Let me know if you would like me to email it to you.

From what you are describing, it sounds like the black layer is actually part of the hull layup in places (since you had to grind through it to get through to the bilge), and if that is the case, I agree it sounds like something used in a previous repair.

Last edited by rhaley; 12-26-2007 at 04:19 PM.
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post #13 of 14 Old 12-26-2007 Thread Starter
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As the pictures show the black is not consistant with the edge of a piece of plywood. It is a layer over a significant part of the hull. My current theory is that the black part is a layer of a prior repair that went wrong. Maybe glass that got too hot. Some kind of patch material improperly applied or cured. I can't imagine what happeded exactly as I have not seen a layer that looks like this before.
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post #14 of 14 Old 12-26-2007
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I'm thinking it's moisture damage either within the plywood or the glass as well in the area around the plywood, and that, at a minimum, the full extent iof it must be revealed and repaired properly. It might be that replacement of the plywood would not only be the best way to approach the project as a whole, but the lack of doing so in a previous repair is what has led to the apparent migration of damage.

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