epoxy barrier coat sun exposure how long is too long?

[johnnyandjebus]

Hello all

My boat has an epoxy barrier coat that was applied 10-12 years ago. The boat is out of the water for the summer and I want to tackle several projects including sanding off the anti-fouling paint. I also have a minor blister problem that needs to be addressed as well as several thru hull's that have been removed and need to be glassed over. I would like to remove the anti-fouling paint this summer and not apply the new paint until several days before drop in next spring. My concern is that if I remove the anti-fouling paint now the epoxy barrier coat will be exposed to the sun and yellow over the summer. Is this a concern?

Most of my blisters are between the epoxy barrier coat and the hull, so by removing the anti-fouling paint now I hope to find other potential problems and fix them. Area's where the epoxy is not adhering to the hull.

Good, bad or other wise I thought I might sand off the anti-fouling paint now and fix the problem areas. To "protect" the epoxy barrier coat I would paint latex house paint over the hull after all repairs are done. The logic being that it would prevent the epoxy from yellowing and would be much easier to sand off in the spring. A good idea or not so much?

My problem is that I live in Canada and to wait until spring to remove the anti-fouling paint can be an issue. Doing this before April is not a possibility and April can be a tough month to get work done. Again the thought being that removing a single coat of latex paint in April will be much easier that removing 10 years worth of anti-fouling paint.

Thanks,
John

[Squidd]

A tarp "skirt" would keep UV off hull

[RXBOT]

In the spring sand with 60 or 80 grit and apply a new coat of barrier paint within a week of when you will apply anti-fouling.

[Stumble]

Johnny,

If you have more than just a few hull blisters (behind the barrier coat) you may have a damp hull. If this is the case you really need to strip the barrier coat now as well so the hull can breath for a year and dry out. If it is just a few isolated spots then that isn't necessary.

If it is just a couple, I would tarp the hull once the paint is gone. Putting latex paint over epoxy may be fine, I have never done it, but a $5 blue tarp from Wal Mart will do just as good a job at keeping the epoxy in good shape, and be a whole lot easier to remove.

[Capt.aaron]

DO NOT paint that nice epoxy coating with latex house paint. Do like Stumble say's and buy a tarp. In 1993 I coated my hull with 5 coats of WEST SYSTEM and the alluminum additive and it's still rock solid. We don't yet know the life span of modern epoxy's because they are still holding strong. You'll greatly compromise the integrity of your epoxy coating in the process of removing the latex. Hell, buy the 40 dollar tarp from Home Dope and cover the whole boat.

[johnnyandjebus]

Hello all, thanks for the replies.

I am of two minds right now.
1) Sand down just the blisters and remove the anti-fouling paint.
If I do this I don't want to tarp off the hull as I want the sanded blisters to be exposed to the sun and wind to help the drying process.
So perhaps I sand down the blisters, let them dry for the summer and remove the anti-fouling paint late into the fall. Then tarp the hull.

2) Remove all of the existing barrier coat and start from scratch.
I am leaning in this direction. My only concern is that it is going to be a mother of a job containing the dust I mean. I have been doing some sanding over the last several nights, both with a palm sander and a grinder with a flap disk. The palm sander isn't up to the job(full barrier coat removal) where as the grinder is. My concern with the grinder is dust collection. So I guess I tarp off the full boat and spend a few days grinding.

Any thoughts on a power tool up to a full hull sanding that also has a reasonable amount of dust collection? Regardless of the hp I don't see a orbital sander up to the task. But I am open to being corrected on this.

John

[CorvetteGuy]

Take it down to the gel coat, do the glass repairs. fair it all out, and wait till you drop her in the drink. Two weeks before launch start the epoxy show.While your last coat of epoxy barrier coat is still tacky, apply the first coat of anti fouling, let harden and re apply ..l.Food for thought

[GaryHLucas]

Originally Posted by johnnyandjebus

Hello all, thanks for the replies.
2) Remove all of the existing barrier coat and start from scratch.
I am leaning in this direction. My only concern is that it is going to be a mother of a job containing the dust I mean. I have been doing some sanding over the last several nights, both with a palm sander and a grinder with a flap disk. The palm sander isn't up to the job(full barrier coat removal) where as the grinder is. My concern with the grinder is dust collection. So I guess I tarp off the full boat and spend a few days grinding.

Any thoughts on a power tool up to a full hull sanding that also has a reasonable amount of dust collection? Regardless of the hp I don't see a orbital sander up to the task. But I am open to being corrected on this.

John

John,
I am doing my bottom right now. Previous owner applied barrier paint over gelcoat cracks and blisters. My boat has be covered on land for 3 years now. Kind of stupid to put it back in the water without fixing the problem. You are right about the orbital and flap disk sanders not being up to the task. I have been using a Ridgid 3" x 18" belt sander with 36 grit. I have it attached to a Ridgid 4 gallon shop vac with a paper filter bag. I also have the heavy duty hose accessory which is far better than the standard hose that comes with the vac. It fits loosely on the sander dust port. When it starts falling off the bag is filled. So far I have filled 5 bags! There is some dust, wear a respirator and googles. However it is far far less than without the vac.

This is brutally hard work. I can only do it for about 6 hours. So far I have about 5 days in it, and should finish my 26 ft boat in about 2 more 6 hour days. Buy lots of belts, I've gone through about 12 already and will use at least 8 more. Knowing what I know now, I'd have gladly paid $1000 to get it sand blasted, and in the water!

Gary H. Lucas

[davidpm]

Originally Posted by GaryHLucas

John,
Knowing what I know now, I'd have gladly paid $1000 to get it sand blasted, and in the water!

Gary H. Lucas

I have heard this every time before. Never has anyone said I'm glad that was done but it was worth it.

[Stumble]

The one job I refused to do when I worked in a boat yard was stripping bottoms. Couldn't pay me enough to make it worth the pain of holding a sander up above my head all day.

There are a few, very few highly skilled guys that can strip a boat with a hand planer. Unless you have a few bottoms to ruin while learning how don't try it, but it is the best way to strip a boat.


These days though I doubt there is a yard anywhere that is using sandpaper to remove the bulk of old bottom paint. It is massively labor intensive, an environmental nightmare, and well known to cause health problems to anyone who breathes in the dust (remember bottom paint was designed to kill living things). At least around here most yards wont even allow you to sand your own bottom, let alone do it themselves.

If you have to strip the boat yourself chemical strippers are the way to go. They are much easier to clean up since the residue can be scraped into a bucket, and take a fraction of the work. Soda blasting is easier, and cleaner, but the machines are rarely rented.

Figure about $40/foot for chemical or soda blasting. For sanding, well again I wouldn't consider it so I have no idea. But it should be pretty cheap since all you are buying is sand paper.

If you happen