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Discussion Starter · #1 ·
The bottom of my little boat is covered with a black mess, I don't think the previous owner was in the habit of cleaning it after he pulled it for the year.

Until a week or so ago I wasn't even sure if there was bottom paint under the gunk.

Anyway, I started with the rudder because it's smaller and easier to fit in the sink than the hull. It's painted with some sort of gray paint and covered with black stuff that only just barely comes off, and a layer of slime over that.

What sort of bottom paint do you think it might be? This is a freshwater trailer sailor, so from what I've read VC17 sounds like the obvious, except it doesn't come in gray. Bearing in mind that I know nothing about bottom paint, how about Micron CSC? It comes in gray and appears to be the sort of thing someone might use for freshwater with a lot of on and the the trailer action.

Here's what it looks like. The left side has been scrubbed with a brush, the right side has been heavily heavily scrubbed with oxalic acid (Barkeeper's Friend) and a Scotch-Brite pad.

Note the careful work the painter put into taping off the edge:


So what sort of bottom paint do you think it might be? And what are my options for touching it up?

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Jebus, that black gunk and slime is hard on there. I spent all evening and still don't have just the rudder clean. That hull could take some work... I actually thought the black speckles were another paint on top the gray, but a lot of elbow grease finally got them off.

Are there any products or techniques that would help get this off? It's only a 22' boat, but still......



Thanks!
 

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I'm with smj, I think that's barrier coat, too. May be the black is some sort of bottom paint attempt, if not garden variety dirt

If you don't know what the paint is, for sure, best to strip it and start anew, however much a PITA that will be, at least it'll be done right
 

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Discussion Starter · #5 ·
I think the black is algae of some sort. At first it seemed like paint, but once I scrubbed a bit it came right off.

Is there a way I can find out for sure if it's a barrier coat? If it's a barrier coat I could paint antifouling over it, right? Of course I'd have to know for sure what the paint is.
 

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Minnesail;
Plus one more opinion that the grey is barrier coat.
Looks just like the interlux 2000E I put on my boat last year.

My suggestion: (you'll need to research if your boatyard will allow it)
- get a decent variable speed Random Orbital sander (like a Makita - about $150)
- sand all the crap off, right down to the barrier coat.
- scuff up the barrier coat and paint VC17 on top.
- put the first coat of VC17 on in your SECOND favourite color.
- second coat should be the colour you prefer.

This way, when you can see your second favourite color showing through, you know it's time to re-apply VC.

Andy
 

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I agree with the others that the gray looks like Interlux barrier paint. If so, I would scrub away the black stuff, and then coat it with a primer recommended by Interlux for use over their barrier paint. Interlux strongly recommends a primer, unless you apply the antifouling paint before the barrier paint has completely cured. I don't know any way that you can confirm that it's Interlux barrier paint. Maybe the Interlux customer service can suggest a way. In the absence of a test, I'd apply an Interlux primer (read all the instructions on the Interlux can that tell you how soon to apply the antifouling after the primer.), and then apply antifouling.

I wouldn't strip off the barrier paint. If that's what it is, the PO probably put it on because he thought it needed a barrier paint. If you strip it off, you might find out why it needs it, and have to put it back on again.
 

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Discussion Starter · #8 ·
Thank you all! Damn, you're smart. A first-time boat owner like me really appreciates this kind of support.

I was looking at the rudder because it was off the boat and easier to access.

However…I had a couple minutes before work this morning so I went out and pulled the tarp off a corner of the boat (trailer sailer, so it's parked in my backyard by the alley) and did a little scraping on the bottom. Here's what I found:

Layer 1 — Whitish blackish gunk that flaked off, probably algae and lake muck.

Layer 2 — Flat blue paint. I'm guessing blue VC17?

Layer 3 — The same gray stuff pictured above, almost certainly a barrier coat like you guys already knew.

I'm guessing the rudder was left with just the barrier coat because it's a pop-up rudder and he thought he'd be pulling the rudder up when not sailing.

So I'm in luck, right? The boat is actually antifouled? If I just scrub off the algae and muck I should be able to apply another coat of VC17 right over what's on there, right? I like the idea of switching colors.
 

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When I said 'start anew' I meant that, because you don't know what the grey is. You would really be hating life if you assumed the formulation wrong and had all your work flake off within just a short time. Interlux ain't the only barrier coat out there - f'rinstance, we use Carboline...

I thought it went without saying, but yes, I'd go and redo all of it, including barrier coat.
 
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