Smoothing boat bottom and painting

[mechjagger]

Need some advice. My cat 22 has vc17 on the bottom and seems to have many layers of paint, it is also flaking/pitting in places. I’ve been sanding for hours with wet 60 grit paper which is very slow going, acetone didn’t seem to do much other than smear it. I see gel coat in places and what I assume is a primer - I’m hoping I’m not setting myself up for failure sanding so much but the vc17 was applied over pits and cracks. Had been told I need to completely sand every spec of copper off which in some cases is taking it down into get coat because of the pits. Does that sound right? After that should I go back over with something like 220 grit?
The local shop said to use marine-Tex to fill the cracks followed by primer inter protect 2001e followed by Micron CF. I’m not sure of this advice because the guy was really confused by the word keel… shouldn’t I be able to use gel coat to just smooth the bottom pits? I’m not sure on the other products he mentioned.

 

[Art12050]

I’m not sure why anyone would put VC17 on a 22‘ Catboat. It’s usually used on slick bottom high performance racing boats.
I would keep sanding till you get all the loose stuff off, then re-coat with a compatible ablative bottom paint. I wouldn’t be concerned with having a perfectly smooth bottom. The main objective of bottom paint is to protect from excessive growth during the season.

 

[jssailem]

Caution as you proceed. You do not want to burn through the gel coat into the glass. Looks like a foormwe owner may have tried to use filler to smooth out the bottom (the light blue) and perhaps tried to address some blisters. Epoxy fairing compound is used to level the highs and lows of your bottom once you have removed all the flaking. Once smooth (you may find a "Long Board" helpful. If is a 3ft or so long flat holder of sand paper, and will help you even out the surface) then a coat or 2 of barrier paint. If you are leaving the boat in the water for the summer, a good ablative would be good. If you are trailering the boat and it is dry during the week, then a hard coat which does not loose it's effectiveness when exposed to air for extended periods would be a better choice.

 

[Davidasailor26]

You will have some work in front of you to get the flaking VC17 off. Unfortunately if it’s flaking that (or having it media blasted) is about all you can do. If you want to continue using VC17 you can leave the well adhered and smoother sections alone. If you want to switch to another paint you will probably have to take it all off, as not much sticks to VC17. No need to sand with 220 after all that - most bottom paints and primers want the substrate sanded with 80 grit to get a good surface to stick to. Any kind of epoxy fairing compound would be good for filling and fairing. Gelcoat is not good for building up a surface - it’s not meant to be that thick, and will be brittle if laid on too heavy. It also isn’t as waterproof as epoxy. After that you’ll want a primer of epoxy barrier coat and the bottom paint.

 

[Tally Ho]

I use VC17 on my O’Day 322 on Lake Michigan.

This spring, I sanded down the hull wherever the vc17 was faking off. I also did some repairs on the rudder (glassed the trailing edge) and ground out the keel joint to check it.

Where ever I glassed or found out the old barrier coat, I went back a couple of coats of 2-part epoxy barrier coat.

Then I applied several coats of VC17 and splashed her.

I would sand it down, try to fill the pits with some fairing compound, then paint with barrier coat and finally what ever anti-fouling paint is used in your local waters.

Is Utica on Lake Erie? If so, VC17 is probably a good choice. I like it because it goes on thin, doesn’t generally need prep between coats, and it dries really fast. I paint every other year, and touch up on the off years. Maybe that is why in needed to sand it this year. I can paint under the jack stands when the yard puts me in the travel lift, and the paint is dry before the hull it’s the water.

Good luck,

Greg

 

[rgranger]

Easy off oven cleaner will make the paint bubble up.. let it dry and then pressure wash…. Or scape

 

[mechjagger]

Thank you all for the advice, gives me confidence I’m not destroying the bottom doing this. I had to learn what a long board is, and will purchase one. I’d like to smooth things at least a little, the previous owner turned this Catalina into a racing boat removing life lines, running everything aft, vc17, etc. I’m on the fence to either put vc back on or change to something like Interlux ACT. It will stay on the water all season on lake Monroe IN, but prefer easier maintenance going forward.

 

[jssailem]

We all compromise our boats to meet our sailing needs.
Use your boat. Discover what you like and dislike. Consider the parts and reason the Previous Owner installed it/used it than reach your own conclusions. It is your boat and you can play with it pretty much as you might enjoy.

So what if the guys on the dock don't understand... They don't get invited aboard for a beer.

 

[shank]

I would stay with the VC17 if it were my boat. It's expensive but there's so much less maintenance compared to other bottom coverings that it's worth it IMHO. Also, as Davidasailor26 pointed out, if you switch to something else you'll have to remove all of the VC17.

 

[Siamese]

I’m not sure why anyone would put VC17 on a 22‘ Catboat. It’s usually used on slick bottom high performance racing boats.
I would keep sanding till you get all the loose stuff off, then re-coat with a compatible ablative bottom paint. I wouldn’t be concerned with having a perfectly smooth bottom. The main objective of bottom paint is to protect from excessive growth during the season.

VC17 is probably the most common bottom paint here on the Great Lakes. We get algae growth, and for many years now, we get Zebra Mussels, and VC17 deals with those very effectively. A lot of Great Lakes VC17 users get two seasons out of an application. Others, like me, prefer to put on a thin coat every spring. I just rough up the old coating with a Scotch pad duct taped to a foam kitchen mop, and roller on a new layer. Never had a problem with buildup, and the bottom is smoooooth.

If that was my Catalina 22, I'd get it down to bare gelcoat, fill any holes, put on an Interlux barrier coat(s), and top it off with a layer of VC17. The really dreadful part would be dealing with the swing keel, which should receive the same treatment. Ugh. Of course, this would depend on whether I intended to keep the boat. If I planned on selling it in the next couple years, I wouldn't bother. Lotta work.

 

[Art12050]

Siamese: Thanks for that information. Makes sense if it works against algae and zebra mussel.
Here on the New England coast it‘s mostly used on racing boats for a slick bottom.

 

[mechjagger]

VC17 is probably the most common bottom paint here on the Great Lakes. We get algae growth, and for many years now, we get Zebra Mussels, and VC17 deals with those very effectively. A lot of Great Lakes VC17 users get two seasons out of an application. Others, like me, prefer to put on a thin coat every spring. I just rough up the old coating with a Scotch pad duct taped to a foam kitchen mop, and roller on a new layer. Never had a problem with buildup, and the bottom is smoooooth.

If that was my Catalina 22, I'd get it down to bare gelcoat, fill any holes, put on an Interlux barrier coat(s), and top it off with a layer of VC17. The really dreadful part would be dealing with the swing keel, which should receive the same treatment. Ugh. Of course, this would depend on whether I intended to keep the boat. If I planned on selling it in the next couple years, I wouldn't bother. Lotta work.

Thanks Siamese, I think given the benefits I will put vc17 back on. Removing the old layers will allow me to fix some pitting and flaking and smooth-things out. I’m wondering if it really requires going all the way down to gelcoat or if I can lay that Interlux epoxy primer over the existing. These technical data sheets for chemicals are a beast to interpret.

 

[Davidasailor26]

Thanks Siamese, I think given the benefits I will put vc17 back on. Removing the old layers will allow me to fix some pitting and flaking and smooth-things out. I’m wondering if it really requires going all the way down to gelcoat or if I can lay that Interlux epoxy primer over the existing. These technical data sheets for chemicals are a beast to interpret.

I doubt you’ll get good adhesion putting Interlux over the VC17. I’d clean the flaky areas to gelcoat, fair, and prime just those spots. Then VC17 over everything.

 

[mechjagger]

Instead of me making a new thread, I can’t seem to find any similar post related to a pattern that is showing up in my gelcoat with some sanding. The boat is heavily oxidized and when using a block of sand paper a nice blue color comes out eventually, but when I used the orbital sander or my DA I’m seeing the cross stitch pattern of fiberglass show up. My question is this serious and should I stop sanding or keep going to try and restore the color? I started with the least harsh polish/ sanding but until I got to 600 grit nothing was changing. My guess is that the cross stitch pattern absorbed the color and kept it dark in places but I can’t tell if I’m removing too much, or of that pattern is close to the surface or not.

 

[jssailem]

when I used the orbital sander or my DA I’m seeing the cross stitch pattern of fiberglass show up

TOO MUCH. The gelcoat is gone when you see the fiberglass underneath.
Solution would be to try and cover with gelcoat, then sand smooth...
Or paint.

 

[dLj]

You sanded through your gel coat. I'm not an expert in applying gel coat. So can't give you advice on reapplying. I would put an epoxy based barrier coat on however you decide to move forward.

dj

 

[Barnacle Bill]

I beg to differ with the comment about VC17 being a paint only racers should use. Because of its effectiveness against zebra mussels, cruising sailors in my area prefer to use it. Other advantages are it is easy to apply, there is no build up over the years and you can launch it in minutes after application. Disadvantages might be.....it is a single season paint, so needs to be applied annually. When you pull it from the water and it dries, like other cuprous oxide paints, a chemical change takes place which renders it not so effective. So a trailer sailor who constantly removes his/her boat from the water over the course of the season, might not choose this paint. But then, if that is how the boat is being used, fouling might not be much of a problem because it isn't in the water long enough to matter. The other thing is practically nothing is compatible with VC17, so it should not be applied over other types of antifouling paints and other antifouling paint types should not be applied over VC17. That is why you are having adhesion problems. Too much of a cocktail going on under the water line.