Antifoul question

[webcraft]

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The antifoul on our boat has come off in (smallish) spots right down to the gelcoat (though I remember putting some sort of primer on in 2006).

Should I spot-apply some sort of primer to these areas before splashing the a/f all over?

- W

 

[Cloven]

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The antifoul on our boat has come off in (smallish) spots right down to the gelcoat (though I remember putting some sort of primer on in 2006).

Should I spot-apply some sort of primer to these areas before splashing the a/f all over?

- W

What I do is scrape off any loose stuff, spot prime the bare areas and then antifoul over the whole lot. If you are using a different antifoul, then it would be better to prime the whole hull before antifoul

 

[sailorman]

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The antifoul on our boat has come off in (smallish) spots right down to the gelcoat (though I remember putting some sort of primer on in 2006).

Should I spot-apply some sort of primer to these areas before splashing the a/f all over?

- W

spot prime works for me

 

[VicS]

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The antifoul on our boat has come off in (smallish) spots right down to the gelcoat (though I remember putting some sort of primer on in 2006).

Should I spot-apply some sort of primer to these areas before splashing the a/f all over?

- W

The GRP should be sanded with 180 to 220 grit paper to provide a key, then primed with Primocon or similar then antifouled. Probably not practical to sand loads of small patches so may not the worth bothering with the primer.

Maybe these were patches that you did not properly key before applying the primer in 2006 or if it was new then patches of mould-release not cleaned off properly.

 

[Halo]

spot prime works for me

+1
Wire brush the loose stuff and use a flat scraper or screwdriver to test that there is some adhesion on the old a/f. Sometimes I have had whole patches up to about 6" square very loose - if so this will come off easily. If large enough area then wet n dry gel coat to help bonding and feather the paint edge with wet wetndry. dry it , Overlap the primer onto the AntiFoul - splash it on with a brush and poke the brush into the edges of the patches.
After many years the a/f may look like a scabby old rhino skin - then you have to bite the bullet and get back to the hull all over

 

[Horace]

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The antifoul on our boat has come off in (smallish) spots right down to the gelcoat (though I remember putting some sort of primer on in 2006).

Should I spot-apply some sort of primer to these areas before splashing the a/f all over?

- W

If you do that it will still come off in other areas & it is a never ending battle leaving you with a surface like the moon in my experience.I think it boils down to having the bottom chemically clean in the first place.

 

[sailorman]

If you do that it will still come off in other areas & it is a never ending battle leaving you with a surface like the moon in my experience.I think it boils down to having the bottom chemically clean in the first place.

I use Jotun which is very soft & easy to fair out.
the worst ever was Optima, it fell off & not possible to fair it out

 

[Horace]

I use Jotun which is very soft & easy to fair out.
the worst ever was Optima, it fell off & not possible to fair it out

I used to use that Jotun because it was cheapest & dried between tides & that is where most of my moon came from

Now I'm not going to bother with any anti-foul & save myself a lot of money time & effort.A couple of scrub off during the summer (if we get one) is preferable.

 

[Halo]

"Now I'm not going to bother with any anti-foul & save myself a lot of money time & effort.A couple of scrub off during the summer (if we get one) is preferable.[/QUOTE]

Good for you if you can get away with it or sail on a lake
If you did that in some places you would be battling barnies for hours

 

[webcraft]

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OK, I'm up for a bit of spot priming. What should I use?

(Pref. something I can get in a wee tin)

- W

 

[sailorman]

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OK, I'm up for a bit of spot priming. What should I use?

(Pref. something I can get in a wee tin)

- W

any under water primer.
primocon
blakes metallic primer

 

[Horace]

"Now I'm not going to bother with any anti-foul & save myself a lot of money time & effort.A couple of scrub off during the summer (if we get one) is preferable.

Good for you if you can get away with it or sail on a lake
If you did that in some places you would be battling barnies for hours[/QUOTE]

I'm in the Solent & you get a good crop that grows over winter & I usually remove them with a scrub off in about April but never been really bothered by them later in the season.

 

[awol]

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OK, I'm up for a bit of spot priming. What should I use?

(Pref. something I can get in a wee tin)

- W

Get a big tin. You'll need it next year again and so on. I was rather hoping my 500ml tin of Blakes primer would last me out - I'll bequeath the remains to you, if you can wait that long.