Antifouling again

[Sofus]

Ref my post yesterday on the same subject.

I scraped off some of the old antifouling using my traditional scraper and found the job going surprisingly smooth. The reason may be that there was no trace of primer and the wood below the waterline had been treated with tar. This has preserved the wood, but I am not sure that modern primers will stick. The tar is impossible to remove as it has penetrated the wood. Any suggestions?

 

[Mirelle]

Should be OK.

If applied over tar, conventional primers will "crocodile" (crack and craze into a pattern rather like crocodile skin), but if the tar is old enough, this won't happen. You may get a little bleed through, but you won't be looking at it.

I don't know how long is "long enough" but my boat's bilges were tarred when new and certainly re-tarred in the 1960's - when I bought her in 1984 I painted then white and they've been painted white ever since. I have not had a problem with the tar coming through.

 

[Sofus]

Thanks again for your valuable advice.

 

[alienzdive]

Best to check with the paint manufacturers re compatability. Possibly there may be some kind of "chlorinated rubber primer" suitable for underwater areas that may be applied prior to antifoul and is suited to under water areas.