Is my bottom paint going to fall off?

cosmoking · #1 (**permalink**) 05-19-2009

I have a cast iron keel that had a bit of rust when I hauled (as is always the case) so we spot-sanded off any rusty spots to bare metal. After going at it for a while some of the spots started to get bigger and bigger, so we decided to take all the paint off the keel down to the last epoxy coat, fill any voids with thickened westsystem epoxy and apply several coats of interprotect 2000e (just to the keel).

This is what we did, except now I am worried that we mistook some old areas of antifouling for epoxy and that the interprotect is over top of that antifouling in some places. We are almost at the point of putting on the antifouling on the whole hull (a few hours to go before the 3rd coat of interprotect is ready to overcoat) and I pulled a piece of tape off the keel and some of the interprotect came off with it, down to a thin layer of blue beneath it.

Is it worth even putting on new antifouling now, or is the interprotect simply going to come off anywhere its in contact with an old antifouling?

Am I going to have to sandblast or strip the keel now and totally start from scratch? If so I'd better go tell the yard guys we won't be launching on Thursday...

JimsCAL · #2 (**permalink**) 05-19-2009

I think you should be fine. I have stripped my iron keel three times in the 20 years I've owned the boat and applied Interprotect 2000. I am sure I didn't get 100% of the antifouling off each time. No problems with adhesion. You do need to lightly sand I2000 between coats if you let it cure completely.

cosmoking · #3 (**permalink**) 05-19-2009

Phew I was starting to get this really nauseous feeling at the thought of sanding the keel again!

But if anyone has advice to the contrary (even if it's not what I want to hear), please do tell. Otherwise going to start putting on the antifouling tonight when the interprotect passes the thumbprint test. Even though it's sprinkling a bit outside, my plastic around the boat has it fairly shielded from the rain... gotta love Seattle.

Sailormann · #4 (**permalink**) 05-19-2009

Quote:

Am I going to have to sandblast or strip the keel now and totally start from scratch?

I think that it would be the best course of action. You MIGHT not have any problems but I would be surprised if the barrier coat lasted as long as it could.

In the winter the metal, the anti-fouling and the epoxy are all going to contract and expand at slightly different rates so there is the potential for the epoxy to work its way loose. If you are in a warm climate it's probably not as big an issue.