What the hull??

[foolproof]

Hello All:

I powerwashed my hull last week (1976 Catalina 30), taking all of the old ablative paint off. While washing, I noticed several areas where it looked like little pieces of the gelcoat were coming off too (I could see what looked like fiberglass underneath). A couple of questions:

1) Do these spots sound like blisters?
2) If so, what is the correct fix? The boat has been on the hard for a few years, so is it properly dried to fix the blisters?
3) What is a good product to use as a barrier coat, and is a barrier coat appropriate?
4) I sail a lake in Kansas; what is a good anti-fouling paint to use - ablative or hard paint?

Thanks for any advice!
Fair winds and following seas.

 

[Ray Bowles]

It sounds like you have opened up some old blisters. If the boat was on the hard then the blisters would have dried out and resessed into the original hull profile. Pressure washing, especially if it was vigorious to remove all stuck on paint, very probably could open some of the blisters and tear off the gelcoat at the edges of these blisters.
It is also probable that these blisters will have to dry out again before repairing.
This would be the time to have someome from the yard or a fellow sailor that is knowledgeable about blisters have a look before going and further.
Good luck, Ray

 

[Ed Schenck]

A Search here on SBO would find you tons of blister advice. Ray pretty much summed it up, that your power washing likely penetrated the f/g so more drying is called for.

I barrier-coated my 1979 Hunter the first year of ownership, 1999. I was told it was not necessary, that it was done blistering if it had at all. I did find a half-dozen quarter sized, maybe two dozen dime sized, and several smaller. I cleaned them out with a Dremel. Then I filled them with a West Systems epoxy mix with instructions from their manual. I finished with five coats of Interlux 2000E barrier-coat for peace of mind.

You will need to ask around your lake about the best anti-fouling for your sailing area.

 

[Eman]

I asked a similar question a few weeks ago and got no reply so I appreciated your input Ed. My concern was/is my 1976 C22 was on the hard close to 2yrs. The PO of course reported no concerns. My concern is that I'd like to get the bottom painted and the swing keel, etc. I was hoping to be able to sniff out any blisters beforehand without putting out for a $$$ paint job. Sounds like putting it in the water is the only sure way...

 

[Jfelkins]

Any chance you could post pictures? Thanks.

 

[Eman]

I'm at work today but will post pic's tomorrow AM, thanks!

 

[Ray Bowles]

Eman, If you are checking for blisters and currently have bottom paint on your C22 then I'd put her in the water for a few days. It will take a few (2 full to 3 days) to allow any blisters to take in water. When pulled out you should look at the interface where the water is drying on the hull. The wet/dry boundry. The blisters will weep water after the bottom paint has dried and will appear very slightly raised. They should be found within 10 minutes of pull out. If they are weeping, then when pressure is applied they will usually spit out a little more water. Once the bottom and bottom paint are dried they will be much harder to see. Mark them with chalk, crayon or pencil for later ID.
Paint blisters will be easy to see on a dry hull and don't usually hold water and will come out when the hull is sanded and need no further repair. They are sometimes mistaken for real blisters.
Dry out any blisters before repair.
Good luck, Ray

 

[Eman]

Ray, that helps a lot, thanks so much...(-;

 

[Barnacle Bill]

If you have blisters, and it sounds as if you do...you must open them up and let them dry out. Sandblasting your hull is one way, or stripping it with a stripper machine designed for this is another. The latter not being so easy to find, but sandblasting is more prevalent. The fall is the best time to do this in Kansas. Then you can let the hull dry all winter long and do the repair in the spring. You must let the hull dry out, or you will be wasting your time and money. Probably the best system for blister repair is the Interlux Paint Companies' Interprotect system. I could explain it all here, but can't take the time now. The method to apply the system can be found in their paint guides or on their web sites. It entails applying epoxy products (which are very waterproof). And, depending on the temperature at the time of application, you can apply a new coat every 2 hours minimum (I think 70+ degrees/look it up). That means you can get 5 to 7 coats on (recommended) in a good long day. Years ago you could only put one coat on in a day, which meant it was a week project just applying paint. There are a number of antifouling paints on the market and depending on how you use your boat (trailer sailor, racer, cruiser, etc.) has to do with the type paint you can use. Interlux again has fine tuned the antifouling paint with some new product just released that is considered to be multi season ablative paints (a bit different than what has been out on the market in the past several years). If you cannot find this info at the Interlux site, or are confused, I can come back and offer info at a later time.

 

[Hermit Scott]

If emans boat has been on the hard for two years, could he chemical peal and scrape the bottom paint to find any blisters? I would hate to have my boat drying for two years only two soak it with water again. Drying time is the hard part.
EMAN-If it were my boat, I would strip the bottom now. Look for any blisters. If you can't see any, which is likely on a catalina 22, then I would paint a barrier protectant on it, and then bottom paint while the barrier coat is still in its curing phase.
Don't put water back in the hull. Getting water out of the hull is the goal, not part of the fix. IF you barrier coat it properly, you will never see any blisters if you can't see them now.

 

[zeehag]

Blisters Donot Flatten Out When A Boat Is Out Of Water. They Stay Bumps On The Hull. Already Fixed Ones May Have The Fix Fall Out If They Were Not Done Correctly. But Blisters Do Not Flatten Out On Land ,lol..after The Next Fix Of The Ones That Fell Out, Do A Barrier Coat So This Hopefully Doesnt Happen Again--but Dont Count On It--individually Repaired Blisters Will Pop Out If They Are Not Repaired While The Hull Is Dry.

 

[Ray Bowles]

About C22's
There will be as many blister finding methods and repairing procedures as there are boat owners.
Blisters can lay flat when dried and be very much harder to find. Just fact. Putting a totally dry boat back in the water simply to look for blisters is a pain in the butt but effective. If you have the time and patience to crawl around and under the boat looking, with a magnifying glass then that's the way to go. Another is to prep the hull, prime and bottom coat this year and look next year at haulout for blisters. If you have a trailer and pull her every year then don't worry about anything but the biggest blisters this year and skip the barrier coat.
Ray

 

[druid]

I had my hull barrier-coated poorly (I'll give the excuse that it was done in winter, and winter here is like 110% humidity for months on end...). Years later, little flecks of barrier-coat would come off during powerwash, leaving the fibreglass underneath exposed.

Could be, your hull was barrier-coated and it didn't stick properly. Proper solution is a do-over.

druid