Antifouling for dummies?

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dedwards

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Having finally bought my first boat, I am now faced with the task of anitfouling it.
Her most recent coat is flaking and peeling away but the coat underneath looks sound. So, what do I do? and does anybody know of any haynes style manuals that would suit my (lack of) expertise?

What I know so far:
1. ya cannae mix n match different types of antifoul.
2. you've gotta wear eye and face protection.
3. start from the bottom so it doesnt drip on your head.
 
Your point 1 is not strictly correct as many types of antifoul are compatible. However, if in doubt I would suggest the following:

1. Scrape off and loose or flaking antifoul and ignore any that is sound unless the build up is huge. If there are very thick layers of old antifoul to remove then I am going to suggest that others on the forum will give better advice.

2. Coat with antifoul primer.

3. Re-antifoul with the product of your choice.

I'm not sure what you mean in your point 3 "start at the bottom". I always start at the waterline and work down to the keel. The stuff dries almost on contact so its not going to run, particularly if you use a roller (the cheap 100mm mini rollers are best and treat them as expendable).

Just be aware that there is about a 3 month max time limit between antifouling and putting the boat in the water. I tend to leave it until a few days before launching - also the weather will probably be better.

Hope this helps
 
You should not worry too much about antifouling.
1. no one can see it
2 at least in my case it doesn't last very long so will need redoing certainly within a year. (you would call it tropics)

Certainly wear rubber gloves and face and head covering. Mine is done while lyinng on my back so glasses as well.

I would not use a primer if the old paint is there. Just rub down a bit with wet and dry sandpaper scotch bright or scouring pad. Then slap the paint on. I have been known to have the boat back in the water within 3 hours with a new coat of A/f which was reasonably successful. Yes a 'orrible job there ain't nothing worse olewill
 
Clean off all the unsound stuff

Follow the maufacturers advice about priming. You should be able to access a little chart that says what to do depending upon the type you are appying and the type you have on already (which you don't know of course) Generally though if you are applying some high tech stuff over low tech stuff you need a primer but if you are only appying low tech stuff you do not.

I agree with the suggestion to use a small roller. A big one wastes too much paint and gets arm achingly heavy before you have finished. You will find the solvent attacks the foam rollers a bit so might need a second before you have finished. I prefer the wooly ones but even they are attacked a bit.

I do not agree with Will H that it is a horrible job I quite enjoy doing it but not the preparation.

BTW do not sand AF dry as it is toxic.

You do not need a "Haynes manual" as the paint makers produce leaflets that will tell you all you need to know and indeed it is all on their websites.
 
If the antifouls turn out to be incompatible then there is a chance that, after a while, the new coat will flake off. My boat had this problem when I bought it. I scraped off the anti foul, back to bare gel-coat, primed and then put new stuff on.

Scraping off the antifoul was a horrible job, but I now know what make is on, and also the damage, repairs etc. it was hiding.
 
If the existing AF is thick & flakey remove it - horrible job but only needs doing once.
f its OK & you dont know what it is seal with a primer - Primacom etc.
Waterline probably needs a scurbable hard AH so you can keep it clean.
Dont use too much when you put new on' - I do a 38' with ONE TIN of Optima - if you use an eroding AF on hull it shouldnt be too bad a jo next time.
I like Optima as its water based and easy to use & rub down before next time - and as I use 1 tin its not expensive - & it works well on east coast. Only prob with it is that it nees 24hrs to dry so cant be done between tides on the posts
 
I would agree with most of what's been said. Only points to add: small 4 inch roller on long handle (radiator roller) is best for reach; the roller is certainly expenable - and a foam type may well disintegrate before you've finished, so have at least 1 spare. Don't be afraid to scrape the old stuff vigorously, you only want to keep what's sticking tight: any doubtful patches are much better knocked off at the outset than lifted later by the roller. Use primer on any areas where you're down to the gelcoat, after a quick sand to give it a key.

Regarding sequence of applying, I do the waterline, then the keel and rudder, then the flat bottom, then the sides, then a second layer on the waterline and the leading edges of keel and rudder. I'm then mostly working away from the wet surface, so inadvertant contact doesn't give me hair of this year's AF colour!

I also switch AF colour year by year, which makes it easier to see that I've not missed any spots or rolled it out too thin.
 
[ QUOTE ]
Use primer on any areas where you're down to the gelcoat

[/ QUOTE ] It should be made clear that that is a fibreglass primer. It is not the same as the primer recommended for use as a barrier coat between layers of incompatible (or unknown) antifouling. IIRC International recommend their metallic primer (normally for wood) as the barrier coat. It's all on their web site www.yachtpaint.com/uk and I imagine other paint manufacturers put similar info on their wesites
 
Thanks guys for the input. I'm only putting on bog standard cruiser a/f so I guess i don't need a primer.

Saying that, there are a few spots where the surveyor has scraped through a number of layers but I don't know if they go through the primer - maybe i'll have to prime those anyway, just in case.

The surveyor suggested removing the loose bits with a wire bush, is there any difference between brushing and sanding?

do I have to worry about what happens to all the scraped off a/f? you know, environmentalism and all that.

cheers
 
[ QUOTE ]
The surveyor suggested removing the loose bits with a wire bush, is there any difference between brushing and sanding?

[/ QUOTE ] try it & do what works best for you. I would scrape followed by a bit of sanding to feather the edges. But dont sand dry as the dust is toxic.

[ QUOTE ]
do I have to worry about what happens to all the scraped off a/f?

[/ QUOTE ] you should do but it rather depends on what rules are enforced by the boat yard
 
French magazines suggest applying antifouling in the bow-stern direction not perpendicularly to the flow of water.
Any thoughts on that?
 
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