Since the guy that did my bottom job did such a lousy job I need to do another bottom job. He just pressured wash the bottom and rolled the paint on. No prep work like sanding.

My plan is to raise the water line up 3". I was going to use the same bottom paint as before. This I can afford. My question is should I sand down what is left of the bottom paint, prime and do two top coats. Which primer should I use?

Also while she is on the trailer I was thinking of painting the mast. A green mast would look cool. I thought about using a 2 part polyurethane paint. Thought on this one also.

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First question is:

What kind of bottom paint are you using?

The PO's technique of power washing, then applying the new coat over the old with *minimal* sanding is just fine if you are using ablative. In that case, the only thing you need to do is "scuff" the bottom with sandpaper to allow the new ablative paint to stick better.

Let us know what kind of paint it is...

BTW: Unless you are taking the boat all the way down to bare gel coat, no primer is required.

The bottom paint was a 45% copper paint from BlueWater. If I remember correctly it was also an ablative paint. There are places where the paint did not stick and came off. Now I have barnacle growth in different areas. Also raising the water line would be on gel coat so a primer would be needed.

I had thought of taking it down to gel coat to do a better job. Because once we start cruising we will not have the trailer or truck to haul her out or the equipment to do the job correctly. Nor the funds to hire someone to do the job.

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Found the paint:

Official Site of Blue Water Marine Paint - Anti Foulings, Topside Finishes, Epoxy Primers, Anticorrosives, Professional Urethanes for Fiberglass, Steel, Aluminum, Wood - Powerboats, Sailboats, Mega Yachts, Coastal Marine, Deep Sea, Mil-Spec, Coast Gu

Looks like they sell a compatible primer too:

Primers Sealers Undercoats - Blue Water Marine Bottom Protect Primer Kit

If it were my boat and I wanted to do it the "yachtsman way", I'd probably do just what you're thinking and take off the old bottom paint. Shaves off hundreds of pounds too!

Did the paint below the ablative chip off where the growth is? As in... did you see many layers of paint chipped off, leaving a deep hole, or did you see just spots where the final coat didn't stick?

If you want perfection, and you have those big craters where many layers chipped off, you could indeed take it down to the bare hull and re-prime, moving the waterline up at the same time. Make sure if you are moving the waterline up, you get all the wax off before you put your primer on. You'll need to buy some solvent for that.

That's probably the "yachtsman" way of doing it if you want perfection.

The cheap way, which will need more attention on the cruise, might be to clean the bottom, scuff it up a bit with sand paper, remove all dust and slap on another 2 coats of ablative. If you need to move the waterline up, you can do that as well, but you'd still have to use the primer and solvent and such on that small part of the job. Now, when you notice you are missing little patches along the cruise, anchor the boat in the shallows where there is a tide and a smooth bottom. Dry the boat out this way, step outside and just do a quick bottom paint touch up. No need for getting hauled out and a quick, 30 min job maybe once or twice a year.

There are several approaches to this. One I used on my last boat was to use non-ablative paint and I just went for a swim every couple months with a broom and knocked some of the growth off. You can't put non-ablative paint over ablative though... you'd have to bring her down to bare gel coat.

Just giving you several "outside the box" ways of dealing with the issue.

If it were me, I'd probably slap the 2 coats on top of what you have now, raise the waterline and touch up between tides, if needed - the cheap way.

What I see is where to single coat just didn't stick. Gotum barnacles growing there now. There is no place around here where the water is clear enough to see the bottom. Looks like mud.

One reason for a good prep is to repair any blister that I might find. Hopefully none but she is a 26 year old boat.

I could do as a friend suggested slap on a coat of bottom paint on and go sailing. Even tho she is a small boat I want to be proud of her as we cruise. There will be a lot of miles before we get back to our home port.

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Ok, so the base layers of paint are sticking well and the other guy must have just messed up in his application of that top layer of paint. You'd be in good shape to get all marine growth off, then just apply more paint. You could do the new waterline with a small quart of primer maybe on your boat, then put more bottom paint over that area.

If your paint was flaking off in huge flakes, showing you many "layers of the onion" below the top coat, stripping off is best. If not... you're ok to just add more paint on. However... if you prefer to take it down, by all means, there's nothing wrong with that. To me, given that the base layer of paint is sticking well and not chipping off, I'd add more paint instead of removing down to the gel coat. Blisters are readily apparent right through the bottom paint... if you had them, you'd see them when you hauled out.

But, if you want to take the paint off, that's better anyhow, because you'll lose some weight.

If you don't see the craters (chipping paint many layers down), I don't see any reason you would have to go down to the gel coat, but... if it makes you feel better to do that, by all means... there's nothing wrong with doing a perfect job. :thumbs:

Back to the original question then:

You'll need to remove all of the bottom paint down to gel coat. Next, mark off where your new waterline is supposed to be (or rather do that in the water?). Take solvent and make sure you get all the wax off the hull up to the new waterline and all the paint residue off down to the keel. Any blisters should be treated before the solvent goes on and will need to dry before you use the solvent on the affected area.

Now, just prime (using the compatible primer I showed in the link above) the hull. Follow any/all directions on the primer can. Also, your hull will be nice and "rough" from your removal of all the other bottom paint, so you'll have a rough surface for the paint to adhere to.

After she's primed, put on several coats of bottom paint. Maybe 3 or 4, since it's all the way down to the gel coat? It can't hurt, really, since ablative washes off. As your last coat is dissolved into the water, the 2nd to last will be there below it, ready to go. When that 2nd to last washes off, your 3rd to last will be waiting in the wings and so on... until you start to see the primer again.

Doing it either way, I'd think you'd be good for two years, if that's really good bottom paint. I'm not familiar with it. I usually use Petit... expensive, but so are those haul outs to paint the bottom.

One thing that I forgot to mention was that when we purchased the boat and hauled her out. As she started drying out the original bottom paint started flaking off. This is why we made the decision of having the bottom done since she would be sitting in salt water.

Thanks Sully for taking the time to answer my post.

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