Hull question - help

[Ima90sJezus]

It's spent all day stripping the bottom of my cat 30, I used franmar soy strip, didn't work like advertised, but that not my issue.

After getting the 75 layers of bottom paint off, I'm down to the "white" I assume this is the gel coat, yes? Well in the white substance there are about a million "pot holes" with another blue substance underneath. This holes are all about an 1/8th inch in diameter.

I assume this is bad? Before putting the new paint on, what should I do? I didn't take a picture of these holes, but I can.

Any advice would be greatly appreciated for this newbie.

 

[Coriolisbc]

Any water coming out of the holes?
That may be the crucial question.

 

[Ima90sJezus]

Any water coming out of the holes?
That may be the crucial question.

There is no water coming out that I notice. Here are a few pictures.

Any ideas?

 

[Coriolisbc]

Oh, that, just the dreaded "boat pox", I just hauled out 3 weeks ago, and found the same thing, cure is to sand down to Fibreglass, re apply a new layer of Gelcoat, then a layer of Epoxy, then new bottom paint. Be sure not to make any gouges in the Fibreglass.

 

[rbmcintire]

The main thing is to remove all contaminants so you can get the best adhesion for the bottom coatings. The guy who stripped our hull used an electric planer, then a DA sander with 80 grit. The gelcoat was cleaned of all previous paint and about 40 blisters were opened up with a small wheel grinder. Everything was flushed with fresh water, dried out a month and then repaired. This surface gives the coatings a nice bite to latch on to. I wiped the whole hull with acetone and applied 5 coats of Interprotect e2000 (3 gray/ 2 white) and then 3 coats of bottom paint ablative. Use roller covers that are made for epoxy so the nap doesn't raise the coatings and cause an "orange peel " effect. Definitely follow the instructions (and weather) to get chemical bonding of the coats.

Rob

 

[Ima90sJezus]

Thanks for all the advice. Looks like I got more work ahead of me than I expected.

 

[Coriolisbc]

RB has the best answer, Don't worry Ima, this will only take a few weeks, and then it is done, and you will have another .5 knots of boatspeed when your hull is smooth.
Mine is done now, and I am happy.

 

[Ima90sJezus]

Follow up

The main thing is to remove all contaminants so you can get the best adhesion for the bottom coatings. The guy who stripped our hull used an electric planer, then a DA sander with 80 grit. The gelcoat was cleaned of all previous paint and about 40 blisters were opened up with a small wheel grinder. Everything was flushed with fresh water, dried out a month and then repaired. This surface gives the coatings a nice bite to latch on to. I wiped the whole hull with acetone and applied 5 coats of Interprotect e2000 (3 gray/ 2 white) and then 3 coats of bottom paint ablative. Use roller covers that are made for epoxy so the nap doesn't raise the coatings and cause an "orange peel " effect. Definitely follow the instructions (and weather) to get chemical bonding of the coats.

Rob

The thing is, it isn't just 40 or 100 blisters. The entire hull, both sides, top to bottom have these blisters... I know this is a major issue, but I do not have the money or time to fix it by sanding all the way down to fiberglass and adding a new gel coat.

My question is, can I just fill all the holes (with what? epoxy?), sand down, primer the whole hull (suggestions? primer? barrier coat?), then paint the whole thing with CPP Antifouling paint??

The boat is scheduled to get trucked out of my yard on July 2nd, all of the above work needs to be done prior to that. Currently in the process of DA'ing the entire bottom, should be complete by Saturday afternoon. I'd like to start filling the blisters on Sunday, so a solution would be great.

Thank you - this is a great place for us beginners to go...

-Ima

 

[rbmcintire]

The " blue" in the pictures looks like anti-fouling paint. One layer is a royal blue and an earlier one looks like a darker blue. Epoxy fairing won't stay adhered in those holes with the paint in them. If you don't have the time or money, I would just bottom-paint it and move on to some other boat project that was doable. It's sailing season, there's always next year.

Rob

 

[jrowan]

I agree with Rob. I wouldn't sweat it too much. By the way, I have filled many small imperfections on hulls with West Sytems epoxy for years. It comes in a caulk gun so it is easy to dab into small crevices or pox and use a plastic putty knife to smooth out. It takes a few days to fully harden & cure. Sand it before then, (when semi cured after about 24 hours) cause it hardens like a rock when fully cured. West is only about 25 bucks a tube - a lot cheaper then expensive Interlux, etc. Many of us sweat the lil things on the hull, when in reality it will be covered with barnacles & growth within about a year or more that will slow it down a lot more then a few minor pox. Be more concerend with a nasty Catalina smile crack then pox. The Valiant 40's are famous for serious blisters that while look ugly do not endanger the boat, just lower its aesthetic (& monetary value) above & below the waterline. That said the Valiant is one of the toughest boats ever built with many circumnavigations under her belt. Don't sweat the small stuff too much. Slap some bottom paint on her, launch, & sail her. Most boats die from rotting at the dock, not sailing.

 

[Ima90sJezus]

The " blue" in the pictures looks like anti-fouling paint. One layer is a royal blue and an earlier one looks like a darker blue. Epoxy fairing won't stay adhered in those holes with the paint in them. If you don't have the time or money, I would just bottom-paint it and move on to some other boat project that was doable. It's sailing season, there's always next year.

Rob

Thanks again for the advice, in the middle of DA'ing now, all that blue bottom paint is coming off. I'll epoxy the holes, let dry, sand, and bottom paint. Launch is July 2nd, about a month behind schedule really, but better than never.

 

[foolproof]

I agree with Rob...what you are seeing is old layers of anti-fouling paint. I had the same thing on my boat, but it was maroon in my case.

Sand with 80 grit on a DA sander until you get to the white gel coat; don't sand too deep into the gel coat! Once you have the gel coat exposed, finish sanding with 120 or 150 grit on the DA until all of the old anti-fouling paint is gone.

At this point you may see some cracking or checking in the gel coat...I did. Repairing it is really simple: mix up some West System Epoxy and use one of those plastic spreaders to apply it to the bottom where the cracking needs to be filled in. In some cases it may be necessary to epoxy the entire bottom if the cracking is bad enough. If so, mix up larger quantities and roll it on like paint.

After you have 2 good layers on, finish sand with 200 grit on the DA, then paint with a good under water primer, which will pretty much replicate the way the factory did it except they used gel coat. Then simply paint with your choice of anti-fouling paint, making sure it is compatible with the primer that you used.

I did this on my boat and got surprisingly good results.