New epoxy coating after stripping antifouling...

[pauldelaf]

Hi,

I have a 20 year old Hunter Duette which was epoxied from new. Since then the one previous owner has rolled on another coat of antifoul each year. When the boat was craned out in october the antifuol was flaking quite badly and so I'm in the process of scraping it all off. As I'm removing the antifoul I'm exposing the original epoxy (and inevitably scraping some of that off too).

My question is whether I should apply a fresh coat of epoxy before I antifoul and also whether I need to remove all of the old epoxy before I do this?

Any thoughts?

Many thanks in advance

Paul

 

[earlybird]

If you re-epoxy, you will have to thoroughly abrade the underlying coating, which will be fairly hard work by hand. I wouldn't bother if 20 years has passed with no problems, especially if you haul out for the winter. You could touch in any scrapes if you are worried. Either way its best to apply a tie coat, eg primocon before you AF over the epoxy.

 

[oldsaltoz]

G'day Paul,

A 20 year old coat of epoxy would not be doing much today unless it was a very good and heavy application in the first place. Also very rare back then.

Before you do anything you need to establish the hull moisture content, this will give a good indication of what condition the existing layup is in.

If low, then you may only need to treat scraped and damaged areas to give you peace of mind.

If on the other hand it's a bit high, it may still not be a problem as you can expect some moisture after 20 years.

If it's very high it will have to be dried out before any further sealing is carried out; though at 20 years without problems I doubt this will be the case.

After checking moisture content I think I would spot repair and fair as needed, wash the areas to remove any residue prior to sanding, then apply a good coat of epoxy primer prior to antifouling.

Avagoodweekend......

 

[vyv_cox]

Removing all of the existing epoxy will be a difficult job and quite unnecessary IMO. I assume that you are going to finish the scraping job off with a sander of some sort, bearing in mind all the warnings about not exposing your lungs to the dust. I have always been perfectly happy with the sort of sander discs that are perforated to allow the dust to be removed from the sanded face using a vacuum cleaner, plus a dust mask. However, you could do it wet if this doesn't entail electrocuting yourself when water gets into the sander. Your sanded surface will then be in perfect condition to either apply antifouling or a couple of coats of Gelshield 200, assuming that the underlying GRP has not absorbed any water.

You may wish to apply Gelshield if you think you have removed a significant amount of the existing epoxy. Otherwise, just apply antifouling. Standard advice if using Gelshield is to put a coat or two of non-eroding on first, then eroding if that's your choice. That seems like a good idea on any new hull, although I have never had a pristine one to try it on. It certainly worked well on my Gelshield.