More AntiFoul Info Required!

[jusw]

It's five years since I bought Treble C (Hunter Horizon 27 TK) and each year I've applied another coat of AF.

The previous owner told me when I bought her that she really needed the old AF taking back to the Gel coat but he hadn't got around to it - So I reckon there is now at least 10 years worth.

So I'm stripping it all back using an electric scraper. - I have a few questions for the panel to advise on:

1 I know the hull was epoxied from new, but what does the epoxy look like? Is it a greyish thin layer just above the white gel?

2 I have mad a few small divets into the gel coat - do these need filling with epoxy of some sort before attempting any painting?

3 When I've got the hull cleaned back to the epoxy, I presume I prime it - any preferred primer and should it be one or more coats?

4 The keels are iron I guess, and of course have some rusty patches as well as an enormous thickness of "paint". Before priming these should I treat the rusty areas with some form of "killrust"?

5 Are the keels epoxied as well?


Thanks in advance

JS

 

[oldfatgit]

Greyish thin layer may be primer, one would hope that epoxy would be thicker (1.5 - 2mm).

A few small divets should be no problem so long as they do not penetrate the Gelcoat which is the protection for the fibre lay up. If they do then you should fill.

I'd use the primer preferred by your chosen anti-foul just to be on the safe side.

I very successfully treated iron keels on old boat by grinding back to metal around rust areas, treating with rust converter and red lead oxide before painting over with epoxy paint. I think it broke the epoxy paint manufacturers rules but repairs worked very well for years.

If you are stripping the antifoul from the keels why not paint all over with epoxy paint before priming and applying new antifoul. This would help your rust treatment as well.

 

[Pasarell]

Grey layer should be the epoxy but it will only be about 0.5mm at most. I think Hunter used to use Blakes so grey is the most likely colour. If you have damaged it and gone into the gelcoat you definitely need to touch up with some epoxy, and if it is only the epoxy damaged it would still be wise to touch it up. In fact, if you have cleaned back to bare epoxy thoroughly it might be wise to put another couple of coats on as you will have scraped some off already.
The keels will be cast iron. If you are grinding them back it is not worth trying to epoxy as you are unlikely to get the metal clean enough. Best will be to grind the corroded areas back to as good a surface as you can obtain, pressure wash with fresh water a couple of times at least. Don't try to substitute a wire brush for the grinder as all you will do is polish the rust, not remove it. Just before you are ready to paint grind it again to remove the flash rusting, remove dust, then apply a rust converter. I'm usually strongly against using converters but this is one of the few times when they may be appropriate. When the rust converter has cured remove any residue with a stiff brush and apply a primer. A conventional primer will probably be best. Something such as International Primocon or a zinc rich primer for immersed use. Make sure you put as many coats on as the instructions say. Cutting back at this point will be a very false economy! Red lead primer will be as much use as gravy on the keel. Finally antifoul

 

[jusw]

Thanks guys, I thought I'd brush some 2 pack epoxy onto any area where I have some white gel showing through, not too much of an area, more scratches really.

I've still got a way to go, lying on my back under the hull! - Great!

JS

 

[Seajet]

Stripping off old antifouling is in my view the worst job one can find on a boat !

This is why I'm a fan of 'self eroding' antifouling.

You mention grey epoxy; I don't know the Blakes stuff but International Gelshield has alternating grey & green layers - 5 in total.

Do be careful & use goggles, overalls etc, I stupidly found out the hard way that oxalic acid 'cleaners' are pretty vicious !

 

[fastjedi]

I watched a Hunter Horizon 27 T/K owner scrape back to epoxy a few years back. They used a sanvik pull back hand scrapper and were surprised how easy it was to remove (2 days) They were left with the grey epoxy, very little damage, touched up with epoxy where necessary, then applied 2x coats of antifoul.

 

[jusw]

Thanks all, I agree, Goggles and a mask are essential parts of the kit Oh and a willingness to get really dirty!

JS

 

[Cloven]

As a Hunter owner could I add the following.

Factory finished Hunters of that vintage only came with two coast of epoxy. Of course yours may have not been finished by the factory in which case it is hard to say what is already there. Best to assume the above. The wisdom now is to have at least 5 or better 6 coats and that is how I prepared my new Hunter hull (6 coats) several years ago - as already said, alternate coats of Green & Grey Gelshield.

Keels should not be coated with epoxy. The original coating is a black substance (VC tar?) What you do depends on their condition. If they appear very rusty, you would be best to either grind them (or better still have then sandblasted) back to the bare metal and then coated with at least three coats of propriety underwater primer (Primocon?) before antifouling. This priming should be done a quickly as possible to prevent any subsequent rusting. If they look OK, I would just wet sand them with wet & dry and then prime & antifoul.

Hope this helps.