What is the proper procedure to re-apply bottom paint? My damn paint is falling off

[mmppirate]

Had a local marine re-paint my boat this past winter. You can see some sport, not too many where it has either chipped or fallen off and the white hull is exposed. Nothing bigger than a few inches. Theres a few spots on the bow and some on the sides. Haven't hit any objects or hit bottom.
Just wondering what is the prop way it should be done and if this is normal.

[Flot]

There are three ways to bottom paint a boat:

- The wrong way: With minimal prep of the fiberglass, bottom paint directly on the hull, almost guarantees the paint will flake off

- The quick way: using a "skip sand" or "sandless" primer, primer goes on your bare fiberglass, bottom paint goes on top of the primer. The important part here though is there is a very short window (as little as an hour) in which you need to apply the bottom paint to the primer as it dries. Some people say it works great, some people say it is garbage.

- The hard way - Sand the bottom, put down 2-8 coats of epoxy barrier coat, put down 2-4 coats of ablative paint. Realistically speaking this will never come off and can't be undone. (short of sandblasting the epoxy off the hull)

The odd thing is that you said you had them "re-paint" - so your boat was painted before...? Sounds like the original paint may not have been prepped properly, or the new paint may not have been 100% compatible with your previous paint. Putting one coat of paint on top of another usually isn't a big deal as long as they are the same 'type' of paint.

[mmppirate]

Originally Posted by Flot

There are three ways to bottom paint a boat:

- The wrong way: With minimal prep of the fiberglass, bottom paint directly on the hull, almost guarantees the paint will flake off

- The quick way: using a "skip sand" or "sandless" primer, primer goes on your bare fiberglass, bottom paint goes on top of the primer. The important part here though is there is a very short window (as little as an hour) in which you need to apply the bottom paint to the primer as it dries. Some people say it works great, some people say it is garbage.

- The hard way - Sand the bottom, put down 2-8 coats of epoxy barrier coat, put down 2-4 coats of ablative paint. Realistically speaking this will never come off and can't be undone. (short of sandblasting the epoxy off the hull)

The odd thing is that you said you had them "re-paint" - so your boat was painted before...? Sounds like the original paint may not have been prepped properly, or the new paint may not have been 100% compatible with your previous paint. Putting one coat of paint on top of another usually isn't a big deal as long as they are the same 'type' of paint.

Yes it already had paint and need to be repainted. Do you repaint every year?

[Menzies]

Originally Posted by mmppirate

Yes it already had paint and need to be repainted. Do you repaint every year?

Not if you have done it right at the outset, and with multiple coats. Depending on where you slip your boat you can get up to 3-4 years with regular cleaning (saltwater), 4-5 years brackish, and longer freshwater, if properly prepared and applied and if you run your boat on a regular basis - that is once or more per week. Plus using the right bottom paint for your conditions.

The yard will take a year (ir even two) off those numbers though!!

[NIGHTIDES]

Just when throught the same process. Had the whole thing stripped to Gel then epoxy barrier coated 3x's, then ablative paint 2x's. Boat performace numbers improved considerably.

You will not be sorry if you do it the correct way.

[NoVacansea]

Just redid mine the begining of this season and pulled it out today after being in all summer and was amazed! Had the bottom soda blasted down, 4 coats of interprotect then 2 coats of micron extra with biolux.

[mmppirate]

Originally Posted by NIGHTIDES

Just when throught the same process. Had the whole thing stripped to Gel then epoxy barrier coated 3x's, then ablative paint 2x's. Boat performace numbers improved considerably.

You will not be sorry if you do it the correct way.

What does this cost per foot?

[aftergolf]

If most of the bottom is in good shape, you can touch up the areas that have come off for another season. In order to touch up, the edges of the bare areas needs to be sanded so there is not a hard edge and the bare spots need to be roughed up so the paint will adhere to the hull.
The other way is to strip off what is there and start from a clean bottom as was referred to earlier with a barrier coat and bottom paint either ablative or hard.

[lostsinker]

Originally Posted by mmppirate

Had a local marine re-paint my boat this past winter. You can see some sport, not too many where it has either chipped or fallen off and the white hull is exposed. Nothing bigger than a few inches. Theres a few spots on the bow and some on the sides. Haven't hit any objects or hit bottom.
Just wondering what is the prop way it should be done and if this is normal.

You say the marina repainted the hull. In other words, the hull had previously been painted.
If so and you see white spots, the original paint is peeling and not necessarily the last paint coat. That means that the hull was not prepped correctly for the first paint job. It is possible that more spots will peel in the future but if the current ones are small, I wouldn't go the route of stripping the entire hull. I would prep and paint the bare spots as well as prepping the entire hull and painting it. If you don't have the problem next season, then only the few spots were not prepped correctly. If more peeling occurs, you have to decide whether you want to continue to spot treat of remove everything and start from scratch.

There is second possibility that the last paint was not compatible with the first paint but in that case, I would expect to see a lot more peeling and usually peeling of the second paint job not the first.

[wingless]

Please be cautious if sanding the bare hull.

The boat manufacturer may have restrictions or guidance to prevent later problems.

My boat was defective from the manufacturer because they primed and painted in the cradle, then bottom painted only in the sling.

This left four regions that had problems w/ peeling. The source wasn't evident until I used my real pressure washer, instead of the toys the marina uses.

My pressure washer exposed those improperly prepared regions.

[tobnpr]

Sorry to say, anything other than stripping to the bare hull (since that's where the bond failure has occurred) is your best course of action.

Short version:
Two years ago (I'm due now for a re-paint) I hauled for a bottom job. All looked fine, until I got a panicked call from the yard early in the morning to get down there as there was a "problem".
The newly applied antifouling, along with probably a half-dozen layers of previously applied paint (I had only owned the boat for a year) was falling off the bottom in sheets. I called my Surveyor, and the factory rep from the paint manuf. came down as well. Turns out that the bond failure occured at a paint layer that was not properly prepped before the job. In the peeled-off areas, you could see the underlying paint layer had no sanding marks- and there was still green (algae) on the paint- it hadn't even been pressure washed, much less sanded.

Over the years, multiple coats of paint continued to add weight- and the newest coats were enough to "break the camel's back". As a twenty year old boat she needed it anyway, but my only course of action was to have the bottom sandblasted bare. Some minor blister repairs, and an epoxy barrier coat was also applied prior to repaint.

You could sand and "touch-up", but the odds are not in your favor that bond failures will continue to occur and more paint will fall off. As the bottom gets rougher from all the uneven coats and "touch-up", it'll affect performance as well.

[OldPete]

Petit Prep Wash
Petit Bio Blue
Petit Sandless Primer (the one with the longer working tim)
Petit Albative Paint

I have 100% adhesion and am VERY happy with the system