New topside paint atop the old paint?

[HopCar]

I don't think you'll need to strip the previous paint. You can do the adhesion test as previously recommended or just prime over the existing paint with an epoxy primer.
Contact the paint manufacturer for their recommendations.

As to paint, I really like Interlux Perfection for application by amateurs. I get great results following a technique developed by Port Townsend Watercraft. In short, you add about 5% extra thinner and roll it on. No need to tip. The paint flows out beautifully. No brush marks. It will look like you sprayed it. Here is a link to where you can down load the instructions. E-Books

[Ryban]

Good replies all around.

There's Interlux Perfection here at the store, and it's about $100 / qt. I should only need 3 or 4 qts, but still, it's going to be an expensive job. However, I'd rather have a good durable finish at a higher cost, than have to re-do it in a couple of years.

[Ryban]

I did an acetone test today, and though a lot of paint didn't come off, I did notice some white on the cloth. I'm not sure if this means I'll be able to get away with painting over. Is this just oxidated/UV-damaged paint that's coming off?

Perhaps this means that it would be easy to strip the paint chemically?

On the other hand, I talked to a guy in the yard today that said I should be able to just sand it all down, apply a primer, sand that, and be good to go. But everyone has an opinion.

[Suijin]

Originally Posted by Ryban

I did an acetone test today, and though a lot of paint didn't come off, I did notice some white on the cloth. I'm not sure if this means I'll be able to get away with painting over. Is this just oxidated/UV-damaged paint that's coming off?

Perhaps this means that it would be easy to strip the paint chemically?

On the other hand, I talked to a guy in the yard today that said I should be able to just sand it all down, apply a primer, sand that, and be good to go. But everyone has an opinion.

Acetone is going to take up pigment on any aged paint, almost without fail.

I agree that you don't need to remove all the old paint if it appears well adhered. I would sand it until all of the gloss is off. If you have a DA sander and the yard will let you use their air it will make short work of that. An electric orbital will work as well. For above the waterline I would actually fill dings and scratches with 3M Premium Marine Filler. Mix an amount that you can apply within 10 minutes, apply with a flexible spreader, bang 10 minutes later it's hard and it sands easily. Fill and fair as much as you can before priming the boat, but you'll see some more flaws spring out after you prime. Hit those again with the filler, fair, reprime and topcoat.

I really would consider putting a primer coat on. Primer acts like "glue" between the existing surface and the new topcoat. It's just part of the prep work and you skip it at your peril. Would suck to have the paint start coming off in a year or two for lack of this step.

[Ryban]

Thanks for the feedback!

I think I'm going to go ahead and get started with the sanding tomorrow. I've got a random-orbit disc sander that I'm borrowing, which should work. I am so grateful right now that I have a small boat.

I'll figure out primer and top coat combinations in the next few days.

Does it matter which I do first in regards to top and bottom paint?

[boatpoker]

Originally Posted by HopCar

I don't think you'll need to strip the previous paint. You can do the adhesion test as previously recommended or just prime over the existing paint with an epoxy primer.
Contact the paint manufacturer for their recommendations.

As to paint, I really like Interlux Perfection for application by amateurs. I get great results following a technique developed by Port Townsend Watercraft. In short, you add about 5% extra thinner and roll it on. No need to tip. The paint flows out beautifully. No brush marks. It will look like you sprayed it. Here is a link to where you can down load the instructions. E-Books

Did a superstructure this way using Perfection and the results are ...... well, Perfection

[HopCar]

Originally Posted by Ryban

I did an acetone test today, and though a lot of paint didn't come off, I did notice some white on the cloth. I'm not sure if this means I'll be able to get away with painting over. Is this just oxidated/UV-damaged paint that's coming off?

Perhaps this means that it would be easy to strip the paint chemically?

On the other hand, I talked to a guy in the yard today that said I should be able to just sand it all down, apply a primer, sand that, and be good to go. But everyone has an opinion.

Acetone isn't a good enough test. You need to use the solvent in the paint.
Here is a link to AwlGrip's instructions for doing the test.
Surface Preparation and Priming - Previously Painted Surfaces Compatibility

[Thumbs Up]

OK moving forward. Since you are willing to spring for the high price paint (perfection) you might as well spring for some interlux primer which will stick to your paint no problem, I think. You only want to sand to 120 grit no finer! You might want to go with an epoxy based filler over the 3m premium marine. Don't lose your waterline. Mask well. and when you paint use vertical strokes to lay off. You are going to need less paint than you think, this stuff goes a long way and it is a small boat. And get ready to sand out the primer with 320 the next day.

[Ryban]

I started attacking the bottom paint yesterday with 60 grit. There are 2 or 3 layers of bottom paint on there, and in some places it's flaking. I'm just hitting these with the sander until they stop flaking and then fairing the edges. I don't think I'm willing to take all the bottom paint off.

There are a couple of spots near the waterline (but below) where there used to be bottom paint and the gelcoat has faded to fiberglass. Should I apply gelcoat to these spots, or just go over them with the epoxy primer?

[Ahneema]

Hi! Before you do anything...talk to a professional from a reputable boatyard! My boat is currently out of the water and being bottom painted. I just got it bottom painted 5 months ago. I thought I could trust the expertise of a boatyard I never had word done through an acquaintance! Boy what a mistake! When I got my boat back to my home port, (different port where I purchased) my bottom cleaning guy took pictures of my hull after I brought it home. It was missing bottom paint in 4 larger areas between the midship and bow, both Port and starboard. I was livid. Called the boatyard and of course it was clearly not their fault according to his 40+ years of EXPERTISE! Whaaaaat? I asked him midway through our conversation how he can determine that without seeing any pictures...(which he wasn't interested in seeing), or even inspecting...long pause..."Anyways, it's not my fault"... Of course, he offered to redo if I was will to spend $800+ in diesel for the round trip back to his boatyard! I would let them touch my boat with a 10' pole! So now, I have my boat with a trusted boatyard, who has done work and has actually redone work from work I had done 5 years ago on my previous boat form another local boatyard. So buyer beware! Talk to some reputable folks befor you get things done!

[Ryban]

I think I'll start a separate thread for my bottom paint concerns just to keep things on topic.

On the other hand, my upcoming sailing plans have me doing a lot of sailing, and not a lot of sitting around -- so who even needs bottom paint!

[Ryban]

I did an adhesion test today with duct-tape, as I couldn't find any clear packing tape in the yard. None of the squares separated, but I'll re-do the test if I run into some clear packing tape in the next day.

I also started sanding with 120 grit today. It seems the paint is very thin in some spots as I hit gel coat pretty quickly.

[keelbolts]

I painted my boat with Interlux Brightside, a one-part paint, almost 10 years ago and it still looks OK. Much of what you hear about two-part paints is true, but is it necessary for your application? A one-part is much cheaper, much simpler/easier to apply, and lasts five or more years before requiring a repaint. Too many people never realize their dreams of becoming a sailor, not just a boat owner, due to consuming all of their time and money gold plating their boats.