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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

why is bottom paint needed?

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HeelinPatrick
Navigator

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USA
102 Posts

Initially Posted - 05/22/2009 : 09:48:57

Ok, so I'll ask the obvious.

I've read thru countless posts here, but haven't found anything on what happens if bottom paint isn't used. Is it just general growth that looks unsightly, and slows you down, or is it more of the things that grow on the boat will break down the fiberglass and do bad things??

I'll first state I'm a lake sailor. This question comes from my purchase of an idasailor rudder. I have used it for a month or so now (works great fyi), and didn't paint it. Some brownish stuff is collecting on it. I called Ida, and she said painting isn't necessary, since it's solid HDPE, can't damage it. But is that the same "isn't necessary" as the bottom of the boat, in that paint would do good in keeping things from growning on it?

Being that the boat is in water 6 months/year, and the environmentally unfriendliness of paint, stripping paint, cleaning, etc., and time needed, it would seem that a seasonal power spraying might be a decent option.

Thoughts/Feedback??

Patrick Moran
1981 SR/SK w/trailer
#2303 - "Chili Mas"
Lincoln, NE

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/22/2009 : 09:55:46

growth is slowed, but not eliminated, on the toxic bottom paint.

The boat still needs monthly bottom cleaning.

If you can haul out and do a monthly pressure wash and you're on a lake, you probably don't really need it.

Edited by - on

aeckhart
Master Marine Consultant

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1709 Posts

Response Posted - 05/22/2009 : 10:28:29

Growth is only part of the problem. Fiberglass, if left emersed in water for long periods of time, will absorb water (osmosis)and create water-filled pockets called blisters. All new hulls are warrented against the formation of blisters, generally for 10 years - at least mine was. A bottom sealer and paint will further retard the formation of this dread fiberglass disease.

If your boat spends a large part of the year on the trailer I wouldn't worry about blisters. As Jim suggests, if you have access to a ramp with an electric outlet or power wash facilities, you can clean your unpainted hull regularly so that marine growth isn't an issue either.

I power wash mine at the end of the season in September. It's fairly easy to clean as long as the growth isn't allowed to dry thoroughly.

Edited by - aeckhart on 05/22/2009 10:32:22

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/22/2009 : 10:29:51

Bottom paint is not necessary on many lakes, and prohibited on some. I never bottom painted my previous boat on a small lake. It all depends on how much growth there is in your lake. Lake Erie grows a lot in the summer and the gulf a little in the winter, so now I bottom paint. See what others on your lake do.

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/22/2009 : 10:31:25

Barrier coats help prevent blistering, bottom paint doesn't.

Edited by - on

bear
Admiral

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USA
909 Posts

Response Posted - 05/22/2009 : 10:37:25

1995 Catalina 250 WB bottom has never been touched except for pressure washing at end of our 5 month season here in upstate N.Y. Boat stays in the water all of the 5 months. I do try and wax it but age and old bones discourage that process at times. I also have an IDA rudder and it will develop some algae, it has never been painted either.....

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Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 05/22/2009 : 12:15:34

It really depends on conditions at your lake. Many at our lake do not bottom paint. Of course the racers do use bottom paint (VC17) or they keep their boats out of the water until race time.

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Stu Jackson C34
Admiral

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844 Posts

Response Posted - 05/22/2009 : 14:32:02

We sailed our C22 on Clear Lake, CA, left her in the water all summer, then trailer sailed from Alameda on SF Bay during the winters. The bottom got pretty scuzzy by Labor Day. The lake had an underwater hull cleaning service: just run your boat over it and the underwater rotating brushes cleaned the bottom! Like a car wash underwater. We never painted the bottom because of this service, but I would not wanted to have cleaned it off by hand, and there were no pressure washers at all on the lake. Your boat, your lake, your bottom, your choice.

Edited by - on

Happy D
Admiral

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921 Posts

Response Posted - 05/23/2009 : 05:34:49

Al,
Don't be mislead here. Blisters only occur when water enters the hull through osmosis, as you stated, and finds unreacted polyester resin. If there is no unreacted polyester resin, there will not be any blisters. Barrier paint only helps stop the intrusion of water into boats that exhibit blisters. Not all boats will blister. Most boats that get barrier coats don’t need it.

I am thinking about only sprucing up the bottom paint on my boat and let it sluff of to see what the bottom looks like. I want to go without but the zebra mussels might be too much for it.

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John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 05/23/2009 : 07:31:15

Plastic (aka fiberglass) cannot absorb water. Time once again for my [url="http://www.yachtworld.com/sealake/sealake_5.html"]favorite article about blisters[/url].

Edited by - John Russell on 05/23/2009 07:31:55

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 05/23/2009 : 08:30:33

Good one John. Here is my favorite blisters site.

[url="http://marinesurvey.com/yacht/BuyingBlisterBoat.htm"]Should I buy a blistered boat?[/url]

Edited by - on

Tom Potter
Master Marine Consultant

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USA
1913 Posts

Response Posted - 05/23/2009 : 09:28:36

I spent the morning waist deep in water standing in mud fighting off jelly fish while scrubbing the bottom of the boat, had quite a bit of barnacles and growth.

I made up a scrubber/scraper using a thin piece of teak as a blade on a squeegee type handle like you see in the gas stations with a scrubber on the other side, worked great. Guess my cheap WM brand bottom paint has given up. Think I'm going to switch up to Pettit Trinidad SR or Micron CSC next time. The boat now lives in a very heavy growth area year round.

Edited by - Tom Potter on 05/23/2009 09:32:39

frog0911
Master Marine Consultant

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USA
1349 Posts

Response Posted - 05/23/2009 : 12:26:53

Tom, welcome to the club of year round bottom cleaning. A boat in the water at the end of your dock does have its drawbacks.

Edited by - frog0911 on 05/23/2009 12:27:44

Nautiduck
Master Marine Consultant

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USA
3704 Posts

Response Posted - 05/24/2009 : 08:39:51

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by frog0911
 Tom, welcome to the club of year round bottom cleaning. A boat in the water at the end of your dock does have its drawbacks.
<hr height="1" noshade id="quote"></blockquote id="quote">
Oh, you guys are breaking my heart.

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KD4AO
Navigator

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USA
202 Posts

Response Posted - 05/25/2009 : 10:55:10

I just got my boat back from the marina with a new coat of Pettit Trinidad. It had an unknown ablative paint that was nearly gone. It now has 2 complete coat's of Trinidad, about 1.75 gallons. I have used that same paint in the past and always got good life out of it. I usually have a diver clean it at 6 weeks to 2 months. I am a firm believer that a good hard paint is a necessity on a boat that stays in salt water in the south.

Edited by - KD4AO on 05/25/2009 11:02:18

Happy D
Admiral

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921 Posts

Response Posted - 05/26/2009 : 17:08:03

An opposing viewpoint.

[url="http://books.google.com/books?id=QzZZcs4hGacC&pg=PA15&lpg=PA15&dq=blistering+and+osmosis&source=bl&ots=Xmm_FcrzGy&sig=EBoRFuwrAq-wKZRuRnhYXr0-pWY&hl=en&ei=W4AcSvteiMK3B6HltYEN&sa=X&oi=book_result&ct=result&resnum=2#PPA15,M1"]Osmosis and Glassfiber Yacht Construction[/url] Page 15.

[url="http://www.insightmarinesurveyors.co.uk/index.php?subpg=blistersosmosis"]Another article talking a bout plastic boats absorbing moisture.[/url]

Time once again for a little more research.
Plastic boats do absorb moisture.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 05/26/2009 : 19:32:15

These articles present some conflicting theories. Keep in mind that very few marine surveyors are chemical engineers--they know boats and engines, and they hear explanations of things like how moisture meters, osmosis, capillary action, and organic chemical reactions work. Their observations, experience, and (it appears) limited understanding of the underlying science produce some varying opinions of how and why things turn out as they observe them. I disagree with some things in these articles and agree with others based on a different background and some different observations. But I'm probably no more qualified to dispute them than they are to write these articles. I'm just saying don't take much of this stuff as gospel. The chemistry and physics of fiberglass laminates is strange and wondrous, and has developed mostly through trial and error. And the stuff (maybe unfortunately) lasts practically forever, even if a little gelcoat blisters away.

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Frank Law
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USA
159 Posts

Response Posted - 05/26/2009 : 19:39:18

My boat is on a mooring in shallow water,(3' low tide) Once we found the rudder missing on our Cat 22 but luckily it floated under some bushes a 1/4 mile away..So ever since I remove the rudder and tiller every time I'm finished sailing for the day..I bolted the tiller to the rudder and remove it in one piece and store it in the cabin It really is not a big problem and keeps the rudder out of the water..

Frank Law
About Time # 3519
1983 SR,SWK

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Even Chance
Captain

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USA
393 Posts

Response Posted - 05/26/2009 : 22:29:54

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by KD4AO
 I just got my boat back from the marina with a new coat of Pettit Trinidad. It had an unknown ablative paint that was nearly gone.
<hr height="1" noshade id="quote"></blockquote id="quote">

Bob, I assume you removed the ablative before you put the Trinidad on. You can put ablative over hard paint, but not the other way around . . .

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KD4AO
Navigator

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USA
202 Posts

Response Posted - 05/27/2009 : 11:04:29

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Even Chance
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by KD4AO
 I just got my boat back from the marina with a new coat of Pettit Trinidad. It had an unknown ablative paint that was nearly gone.
<hr height="1" noshade id="quote"></blockquote id="quote">
Bob, I assume you removed the ablative before you put the Trinidad on. You can put ablative over hard paint, but not the other way around . . .
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes, they removed the ablative paint then applied 2 complete coats and a 3rd around waterline.

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bigelowp
Master Marine Consultant

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USA
1787 Posts

Response Posted - 05/29/2009 : 05:20:18

In my humble opinion I fully disagree with the folks ad Ida regarding HDPE or any non-fiberglass plastics. I painted my Ida balanced rudder, son washed off too much of the ablative paint and I had lots of barnacles which pitted just like on fiberglass. I also own a Logic (Now Triumph) "plastic" skiff. Love the blat, but it needs bottom paint and even that company, after one year of production saying it did not need bottom paint, now say it very much does. Marine growth --from fresh or salt, clean or polluted -- will grow, in time, unless the available tools (read paint) are applied and maintained. In western Long Island Sound, a salt water area that has relatively warm (70 degree) water in summer and is not the cleanest area of the Sound, I use ablative paint and lose one full coat each short summer. On your lake, you may go a couple of years with a different type of paint, but, you will need something! And, besides, painting the bottom is an age old right of passage to see if you have any friends who really want to go sailing with you during season!

Enjoy.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 05/29/2009 : 06:47:41

That may reflect the extreme difficulty in getting anything to adhere to HDPE without heating to 200º and painting or gluing within 20 minutes. To the surprise of the marketing departments, either barnacles own little torches or nature can do things we can't. :)

Edited by - Dave5041 on 05/29/2009 06:48:38

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 05/29/2009 : 09:58:55

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Dave5041
 T...either barnacles own little torches or nature can do things we can't.<hr height="1" noshade id="quote"></blockquote id="quote">Every day, barnacles and skunks demonstrate the superiority of Nature's chemical engineering prowess over mankind's!

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