Association Forum - Bottom painting

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Bottom painting

New Topic

Topic Locked

Printer Friendly

Author

Topic

johnnkay
Deckhand

Member Avatar

USA
8 Posts

Initially Posted - 09/28/2005 : 18:54:47

I recently bought a Catalina 25 and have it out of the water for painting. How important is it to sand the blisters? Can I just pressure wash the bottom and repaint.

John Bargmann

Edited by - on

Frank Hopper
Past Commodore

Members Avatar

Pitcairn Island
6776 Posts

Response Posted - 09/28/2005 : 19:16:25

Oh man, what a question.
IMHO
Our boats are of limited value so you need to be careful not to put too much money in one. I put almost ten grand in a 7 grand boat that I sold for 8.5, be careful it can happen to you. Blisters are a matter of degree and compulsion, Most people should ignore them and sail the boat. If they are really bad, say fifty cent to silver dollar than you should grind them out, let them dry for weeks at least and then fill them and fair them, once you have begun the blister repair deal though it is pretty hard not to put a barrier coat on the boat and before you put a barrier coat on the boat you should fix virtually all blisters. See what I mean about the question? If they aren't too bad, nickels and dimes and less than 100 of them then you should paint and sail.

Edited by - on

ClamBeach
Master Marine Consultant

Members Avatar

3072 Posts

Response Posted - 09/28/2005 : 19:19:27

Blisters on the bottom of a boat are typically due to osmotic water infusion in the fiberglass layers underneath the gelcoat rather than simple bubbling of the the bottom paint itself.

If you sand a little patch of bottom paint off around a blister you'll find out for sure if the glass is blistering under the gelcoat. Slicing the blister with a razor blade will usually result in an outflow of water trapped in the pocket.

If left 'untreated' the fiberglass resins will begin to deteriorate where the water has penetrated the hull causing de-lamination (a bad thing). Repairs typically involve grinding out the blisters, letting the fiberglass dry out and re-filling the damaged area with an epoxy resin mix.

Overcoating the entire bottom with epoxy or other 'barrier coats' will pre vent a re-occurance of the blisters.

Edited by - on

johnnkay
Deckhand

Members Avatar

USA
8 Posts

Response Posted - 09/28/2005 : 19:36:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by fhopper@mac.com
 Oh man, what a question.
IMHO
Our boats are of limited value so you need to be careful not to put too much money in one. I put almost ten grand in a 7 grand boat that I sold for 8.5, be careful it can happen to you. Blisters are a matter of degree and compulsion, Most people should ignore them and sail the boat. If they are really bad, say fifty cent to silver dollar than you should grind them out, let them dry for weeks at least and then fill them and fair them, once you have begun the blister repair deal though it is pretty hard not to put a barrier coat on the boat and before you put a barrier coat on the boat you should fix virtually all blisters. See what I mean about the question? If they aren't too bad, nickels and dimes and less than 100 of them then you should paint and sail.
<hr height="1" noshade id="quote"></blockquote id="quote">

Edited by - on

johnnkay
Deckhand

Members Avatar

USA
8 Posts

Response Posted - 09/28/2005 : 19:41:11

Oops, not that great with the computor. Just wanted to thank you for your response and I will just be painting my boat and forgetting the few nickel and dime blisters.
John

Edited by - on

weluvlife
Navigator

Members Avatar

166 Posts

Response Posted - 09/29/2005 : 21:05:02

Hi John,

For the rest of you, I'm the one that sold poor John this boat with all of the blisters :(

I do agree with previous posts concerning your questions.

Although, I must add, that you should add some epoxy barrier protection against further blistering. i.e. Interlux 2000 for example.
Apply your antifouling paint over this.

Mark

Edited by - on

existentialsailor
Master Marine Consultant

Members Avatar

USA
1180 Posts

Response Posted - 09/29/2005 : 21:56:42

A barrier coat over blisters without dealing with them is worse than doing nothing as it can make the problem worse. If they aren't of significant size and number as Frank said, just paint over them. If you are going to fix them, epoxy is good, but vinylester is better and I recommend you explore the process in depth. My boat, which had a tremendous blister problem and was repaired with vinylester, will be hauled in about a month. I'll then see if the repairs worked well or not and I'll let everyone know so they can benefit from my experiences.

Edited by - on

weluvlife
Navigator

Members Avatar

166 Posts

Response Posted - 09/29/2005 : 22:43:05

So many of us have so much to learn when it comes to bottom jobs, myself included.

Could you explain why adding epoxy barrier coating over smaller blisters would be worse than no paint at all?? I would think that by just adding antifouling paint directly over the blisters would help to accelerate the blister growth??

Thanks,

Mark

Edited by - on

Frank Hopper
Past Commodore

Members Avatar

Pitcairn Island
6776 Posts

Response Posted - 09/30/2005 : 03:45:31

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by weluvlife
 So many of us have so much to learn when it comes to bottom jobs, myself included.

Could you explain why adding epoxy barrier coating over smaller blisters would be worse than no paint at all?? I would think that by just adding antifouling paint directly over the blisters would help to accelerate the blister growth??

Thanks,

Mark
<hr height="1" noshade id="quote"></blockquote id="quote">
The barrier coat prevents stasis by trapping the fluid and gases under the epoxy. The blisters then must migrate into the hull as more gases are formed.

Edited by - on

weluvlife
Navigator

Members Avatar

166 Posts

Response Posted - 09/30/2005 : 08:09:21

This is good information. Thanks for sharing your opinion. I appreciate it.

Edited by - on

MattL
Admiral

Members Avatar

USA
990 Posts

Response Posted - 09/30/2005 : 11:32:44

I talked to a lady at WM tech support a few months ago and asked about bottom coat and barriers. I told her my boat was in cold fresh water for about 6 months out of the year, trailer the rest of the time, and occasional ocean trips through out the year. We have had the boat for about 5 years and I am just starting to get some growth on the ablative paint. I do have a few spots where the current barrier coat has flaked off. She told me that I didn't need to put a barrier coat on because there is only a problem with blisters if you keep the boat in salt water for extended periods.
Any thoughts on this?

Edited by - on

ArgonautEC
Deckhand

Members Avatar

USA
11 Posts

Response Posted - 09/30/2005 : 12:02:23

Not, true....blisters can be a problem even in the ponds of Kansas. We're as far away from salt water as you can get. :-)

Edited by - on

Frank Hopper
Past Commodore

Members Avatar

Pitcairn Island
6776 Posts

Response Posted - 09/30/2005 : 12:04:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by MattL
 I talked to a lady at WM tech support a few months ago and asked about bottom coat and barriers. I told her my boat was in cold fresh water for about 6 months out of the year, trailer the rest of the time, and occasional ocean trips through out the year. We have had the boat for about 5 years and I am just starting to get some growth on the ablative paint. I do have a few spots where the current barrier coat has flaked off. She told me that I didn't need to put a barrier coat on because there is only a problem with blisters if you keep the boat in salt water for extended periods.
Any thoughts on this?
<hr height="1" noshade id="quote"></blockquote id="quote">
She is wrong.
Come to Kansas and I will show you blisters in the same frequency as on any coast.

Edited by - on

existentialsailor
Master Marine Consultant

Members Avatar

USA
1180 Posts

Response Posted - 09/30/2005 : 14:47:21

MattL,
The type of water a boat is in really makes no difference. If anything, blisters seem more prevalant in boats kept in fresh water than boats kept in salt water. Essentially, most experts on the subject seem to concur that blisters are the result of the manufacturing process when the boat is built. The resin was not adequately impregnated into the fiberglass during the layup process. The fibers wick the water that gets through the gelcoat (gelcoat isn't entirely waterproof, even less so as it ages) and the reaction between the resin and the water causes the blisters. There are of course other theories and I greatly simplified the explanation, but the gal at WM was dead wrong in what she said. I have read that boats that are sailed in fresh water and salt water seem to have less incidence of blistering.

Edited by - on

MattL
Admiral

Members Avatar

USA
990 Posts

Response Posted - 10/01/2005 : 02:26:49

Rick,
How about what I said about only being in the water for six months, then on the hard most of the other time. Does this drying out help in the prevention of said blisters?

By the way this is cool, I like all the responses being given that are benificial to novist as well as old timers.

Edited by - on

Gloss
Master Marine Consultant

Members Avatar

USA
1916 Posts

Response Posted - 10/01/2005 : 08:08:23

Here's a blister story with a happy ending.
When I had my boat surveyed, and pulled from the water for inspection there were a couple hundred dime to quarter sized blisters. I used that to help negotiate the price down. after the boat was on the trailer for a few weeks the blisters disappeared. They were paint blisters. Lake Norman in North carolina, where I found my boat, is one of the worst blister lakes in the country, as it is shallow and gets very warm. Clear lake in Texas is also very bad for blisters (in addition to the extreme pollution, and barnacles)
One of these days I will repaint my bottom, and I will put on a barrier coat first. But of course the 89 models have a vinyl ester resin hull which is blister resistant.

Edited by - on

existentialsailor
Master Marine Consultant

Members Avatar

USA
1180 Posts

Response Posted - 10/02/2005 : 15:39:38

MattL,
If they are real blisters and not paint bubbles, the 6 months out will not dry them out, they have to be ground open. My boat spent 4 years on the hard and it did nothing to dry out the blisters. Once the chemical reaction starts, it doesn't go away without interaction on your part. That is of course if they really are osmatic blisters. It's not ascommon as the paint/barrier coat manufacturers would like you to think.

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.