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Discussion Starter · #1 ·
I just finished scraping 19 years of paint of my bottom and have sanded the entire hull down to nice clean and smooth gelcoat with 120grit paper.

I'm being told a number of things on what to do next and thought I'd get some more opnions.

Reccomendation 1 (from the broker I just bought the boat from) is to put 1-2 coats of a epoxy based barrier coat on, then 2 coats of ablative paint.

Reccomendation 2 (from a friend who used to have a O'Day 16 a long time ago) is to use a regular primer paint and then 2 coats of ablative paint.

Reccomendation 3 (from west marine sales rep) is to skip all base coats, apply 1 coat of ablative in white or grey, and then 2 coats of ablative in blue (I want the final hull color to be blue) because "since hull is 19 years old and freshly sanded, the paint will stick to the gelcoat better than it does to primer"


Any suggestions on what course of action I should take here would be greatly apprecieated.
 

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Tartan 27' owner
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I think you are supposed to put more then 2 coats of the barrier coat (ie., Interlux 2000) on. Reading the label and actually following the directions with most of this stuff helps.
Your broker probably did not want to go into the detail that is on the label.
 

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In my opinion the boat is old enough to develope osmosis. If it didnot develope osmosis till now, it is less likely to develope it from now on. To simplify things I can say that the gell coat made its duty to protect the boat. Just apply your antifouling.
 

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Given the boat has no blistering, if you are going to use it in the same manner that it has been used in the prior 19 years (same water, same season length), then I would not bother with barrier-coating (which is 4-5 coats at least).

I would proceed with recommendation 3, be sure to follow the paint prep instructions, including sanding the bottom with 80 grit paper first.
 

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As you can see, everyone has a different opinion. Let's try this another way:
Safest approach - barrier coat and then paint
Expedient approach - just bottom paint
Strange approach - regular primer paint and then bottom paint.
 

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Discussion Starter · #8 ·
a friend of mine (in the process of doing the exact same thing on his Catalina 25) called Interlux today and they told him not to use any barrier or primer, go straight paint....

seems like I'm probably not going to get a concensus on what is the reccomended way after all... (Gary, I agree with your logic, I only question if it actually makes a difference, or it's just peice of mind)
 

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seems like I'm probably not going to get a concensus on what is the reccomended way after all...
Bingo! There is no 100% correct approach. Chances are an older boat in the Northeast that has not blistered and is hauled each fall will not have problems. You will probably be fine with just bottom paint. The barrier coat is like insurance. Your call.
 

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It is my understanding that all fiber glass boats absorb water and if left in the water for years it can add hundreds or thousands of pounds of weight to the boat. I always thought the barrier coat was to prevent this. iirc
 

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It is my understanding that all fiber glass boats absorb water and if left in the water for years ...
I do not believe this to be true, although it is true that leaving a boat in water for years significantly increases the chance that it will develop blistering...but that is not guaranteed to happen.

OR IS IT? I assume many boats without barrier coats live for years in locales like Florida without blistering...but what do I know, I live in new England. Can any Florida posters clarify whether blistering in a year-round-environment is a common exception, or a rule?
 

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Whatever you do, you cannot completely protect fiberglass. Whtever you apply will cause water to penetrte to it. Gellcoat is permeable to some extent, Epoxy is better but not waterproof. For blistering not only water but some chemicals are also needed. They are generally present in the plastic of the hull. It depends on their quantity to bond with water and form blisters. That means osmosis is not the real reasonof blisters but the chemica reaction with water and the chemicals inside the fiberglass.

The amount of water in the hull is not as much as it is thought. A dry hull has a maximum of 1 - 1,2 % water in its content. The maximum is something like 3%, which means the boat will be heavier maximum 3% of its hull weight.
 

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Why be as good to your boat as possible, since you have stripped now? (It maybe the last time is it ever in that state.) Go with several coats of Interlux 2000e (barrier coat) and then ablative paint. Follow the timings that are required.
 
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