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Old 02-12-2015, 18:36   #16
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Re: Bottom job blues:(

Thanks y'all for the great input. Seems I have lots to learn, especially when it comes to what exactly what is there already.

Who, not including the folks at the yard, could tell me what I have exactly. If it is indeed a vinylester barrier coat what exactly does it look like? The topsides are flag blue, and to my knowledge has never been painted. Lots of the other sisterships of this particular Bene have the flag blue hull. I think all of the ones configured in the "owners version" with only two staterooms came in this color.

When you look at the bottom the areas where the ablative paint haschipped have that same blue color showing. Can I assume that this is the vinylester barrier that covers the entire hull. If so what do I do just sand the old paint completely off and if no blisters etc just reapply a suitable bottom paint.

Been reading through previous issues of practical sailor and can't find what to do in this particular case.

Thanks again for the insights, keep em coming!

Will
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Old 02-12-2015, 19:02   #17
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Re: Bottom job blues:(

Quote:
Originally Posted by Clipper4730 View Post
Thanks y'all for the great input. Seems I have lots to learn, especially when it comes to what exactly what is there already.

Who, not including the folks at the yard, could tell me what I have exactly. If it is indeed a vinylester barrier coat what exactly does it look like? The topsides are flag blue, and to my knowledge has never been painted. Lots of the other sisterships of this particular Bene have the flag blue hull. I think all of the ones configured in the "owners version" with only two staterooms came in this color.

When you look at the bottom the areas where the ablative paint haschipped have that same blue color showing. Can I assume that this is the vinylester barrier that covers the entire hull. If so what do I do just sand the old paint completely off and if no blisters etc just reapply a suitable bottom paint.

Been reading through previous issues of practical sailor and can't find what to do in this particular case.

Thanks again for the insights, keep em coming!

Will

Sounds like the blue is original gel and you are looking at a skip sand job. When you peel off a big flake down to the flag blue, is the flag glossy? Even slightly? Does it have a light roller stipple of a greenish material? Should be mostly transparent. This is very common. Many manufacturers ship their boats in a bare gel bottom, because most bottom paints are inactivated by long term exposure to air. Therefore the bottom is painted on commission, usually by whoever the broker has hired to commission the boat on delivery. Many builders, Bene being one of the most notorious, actually recommend that this be done by a process called "skip sanding". This involves heavily dewaxing the hull (at least three passes of 202 using two rag method), followed by rolling on a coat of an acid etching primer. This is supposed to etch the gel for adhesion, and prevent you from having to sand the bottom. Many manufacturers will actually void the warranty on the bottom if you sand the gel, potentially opening up porosity and causing blistering. However, long experience has shown that the skip sand method sucks big time. It will provide ok adhesion out the gate, though it will not pass a full adhesion test (which nobody ever does). But it will cause a full failure and flaking back to the gelcoat, usually in a 5-10 year window, occasionally more if the degreasing was extremely thorough and it was skip sanded twice. I have seen it a great many times, it's almost always the case when you see BP flake back to the original gel.


The prices you have posted are vaguely reasonable for the described work, but the approach is all wrong. Get rid of the soda blaster and find someone who can sand it to bare gel instead. This will cost half as much or less (it's a three day job for me, including tenting and clean up). It will also provide dramatically superior tooth for the barrier coat to bond to. Don't worry about voiding the warranty, it's not worth the paper it's written on. And you don't have to worry about harming the integrity of the gelcoat; that's why they are applying the barrier coat. However, four coats is considered a minimum to actually provide barrier protection (10 mils DFT). Less is ok if you are just using it to seal the gel and act as a tie coat to the bottom. Which brings me to the most important part: be certain the bottom is dry before coating (preferably via a proper moisture meter reading), and be certain that the bond window between the final coat of barrier and the first coat of BP is not missed. Also, this is a good opportunity to pursue a marker coat if you are using an ablative paint. Apply one coat red, then two coats blue or black. When you see red showing, you know its time for new BP.
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Old 02-12-2015, 20:37   #18
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Re: Bottom job blues:(

I had a similar sounding problem on Cbreeze shortly after I purchased her at year 14. Flaking bottom paint with the appearance of a wash primer as the first tie coat. Tried several approaches and then discovered that by using a painters tool that I could just scrape the old bottom paint off without a lot of trouble. A painters tool is kind of like a heavy blade putty knife. Keep a file handy to keep a sharp edge. Three of us did a IP32 bottom in a weekend (and it is a low dust operation). Collected most of the scrapings on a plastic drop cloth. Cleaned everything with lacquer thinner, single epoxy tie/ primer coat, bottom paint and no trouble now 10 years later. Suggested the same process to a fellow IP owner a few years later and he pulled a repeat with similar results.

If the paint is not adhering to the bottom then there is a good chance that it was a bad original prep. Could be a just some spot problems but the painters tool should tell you what you are in for. Cheap experiment to try.
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