Antifouling

[benri]

My boat was in the water for just 2-3 weeks last season and the antifouling is practically intact. Do I still need to give it a coating before putting it down again in summer and do I need to sand off the previous coats?

[suffrun]

though I am no expert on the subject I believe that you need to reapply the antifouling because since by summer its effect, as an antifouling agent, would have worn off. Before applying a fresh coat I suggest that you rub down the previous coating.

[kris]

i agree with suffrun 100%

antifouling works like this:

you apply 2 coats before putting it down for the season.

when it is in the water, antifouling, apart from having chemicals that do not let plant life and koccli attach themselves, will rub off very thin layers of itself. this means 2 things:

1. the layer of antifouling will rub down and eventually the primer would be uncovered.

2. the chemicals which are in the antifouling will lose their effectiveness and thus algae and koccli will still attach themselves.

so the best thing to do is rub out with a fine sand paper the previous coating. no hard sanding is required, just to remove the very top layer which was in direct contact with the water.

then give a coating of antifouling a few days max before putting it again down. hope this was of help benri.

kris

[benri]

thanks kris & suffrun! Any idea of what grade of sandpaper I should use - Is it ok to use a sander?

[kris]

np benri.

regarding thickness of sand paper i think that you shouldn't use thicker than the 100. if the top coat of the antifouling is practically intact then all you have to do is give a light sanding with a sand paper of about 150.

regarding the sander, yes you can definately use it. just be carefull if it is not a finishing or orbital sander then i suggest that you should'nt use it, as belt sanders are not intended for that job and can literally dig a hole in your hull.

kris

[skip]

This is something I was thinking of as well. I used a hard antifouling this year and it remained pretty much intact. International say light sand and coat over. The thing is that you don't want to accumlate too many layers on the hull as aside from drag, when they accumulate you sometimes get whole chunks coming off.

Might be best to almost strip down both coats in my case down to the gelshield

[shanook]

Nick thats why i told u to give a first paint of a different colour. So that u sand down to that first colour paint without touching the gelshield. Dont sand too much try to use a wet and dry paper as the antifouling dust is not compatabile with ur stomach linings.
Have fun, its a sh. . .  job but has to be done. its good exercise as well.