GRP Osmotic Blisters

[SKYCHENEY]

I'm going to say this more carefully: On a Hatteras blisters are rarely, if ever, more than cosmetic. Show me one Hatt that has had a hull with blisters that have become a structural problem. I have never heard of it happening, have you? Have you even heard of one with severe delamination or anything that went deeper than the skin-out matt? If you look at most, it's not deeper than the gel coat. Let's be careful and not assume that the problems that happen to other FRP hulls do or will also happen to a Hatteras hull. I'm not saying that it can't happen. I'd just like to know of one that has had serious problems. And, I hate to see yards take advantage of people to do repairs that may not even be necessary.

[spartonboat1]

Have you even heard of one with severe delamination or anything that went deeper than the skin-out matt? If you look at most, it's not deeper than the gel coat. Let's be careful and not assume that the problems that happen to other FRP hulls do or will also happen to a Hatteras hull. I'm not saying that it can't happen. I'd just like to know of one that has had serious problems. And, I hate to see yards take advantage of people to do repairs that may not even be necessary.

My surveyor of 11 years ago, did say that he thought he detected some delamination, via rubber hammer tapping, but did not flag it as a show stopper. Oddly enough, the worst blisters I have are up in the seating trunk area forward, where water stands/sits under the cushions, because the covering was not water proof by previous owners. But the bottom is in very good shape.

Don't know that I needed it, but had the bottom barrier coated 7-8 years ago; not cheap ($8k or so). I ran into the tech who did the work, who had left the yard. He said I really didn't have that many blisters and none severe (a 1972 43' MY). The major issue I find is at the keel, where its been dinged up over the years and has some 1/4' chips out of it, i.e. not baby bottom smooth.

The one thing I would say, is that if one were to barrier coat, then don't gel-coat "peel". The sand blast or better yet, soda blast, is more targeted, so major issue areas are attended to. Why strip the entire bottom of gel coat, if the issues are far and few between. I just personally took all paint off down to my barrier coat and found some thin coating or non-existant. For what it cost me to have it barrier coated, I almost wish I had done it myself. But I was on the road at the time and living in another state, so logistics made that out of the question.

So should it be done on a Hatt? Yes. But to comprehensively knock off all the gel coat?- No. Strip all the old bottom paint to the gel coat, run multiple checks for moisture, to verify she is dry, and perform thorough inspection for mechanical appearance of blisters. Repair those that are there, re-inspect, then fully barrier coat, and then re-bottom paint. I would also think that a baby-backside smooth bottom should also be the result! Barrier coat, then sand it out with 150grit. If you go to the VC-17, then hit with 300grit final sand. Barrier coat smooths out nicely.

I now have hands on experience with barrier coating and it is easier than painting, IMHO. Very long pot life and easy to work. Four coats is the recommended, or about 10 mils- as the documentation says, thickness is the important factor. So a good barrier coat is valuable again, IMHO.

Big Ditto on having a Class A yard do it, or at least Class A work. I would absolutely arrange to come and observe/inspect the progress, after what I went through with my yard. Check points include: during stripping, after fully stripped, after removal of identified blisters, and after blister repair. Finally, how many coats of barrier applied and final appearance before re-paint. A long wish list for inspection I know. My Yard Manager was not that friendly, so some pointed discussion might be needed, before they agree. If their work is good, why should they care...they should be willing to "show off" the quality and progress.

Another long post...

[spindrift]

As a followup, the article in Power and Motoryacht talks about the benefits of using vinylester resin versus epoxy resin. Seems that vinylester presents a much better moisture barrier. I talked to the production guys last week at Hinckley and Legacy.. they advice this is the way to go.

A side note, I did have a problem with a Nautor Swan, a class A quality boat, that I refit. The osmosis was left unattended, and got into the laminate. We had to lay in a couple of layers of cloth on one strip of cloth on the ports side of the boat. Ran the cost up quite a bit.

RE: the internet. Remember poor old Pierre Salinger who claimed a US Navy missile test brought down TWA Flight 800. He never lived that one down.

[Fanfare]

Even if damage is cosmetic I would not want it to get out of hand. Around 25 or so years ago I had Fanfare's bottom coated. Four years ago my attention was called to some small blistering at her annual haul out. Three years ago the pox was spreading and quarter sized, so I arranged to have the bottom peeled, dried and recoated during the summer months when we wern't using the boat anyway. The amount of old bottom paint that came off was astounding (KL 990). I knew that stuff was heavy from lifting the cans, but hadn't realized how much stayed on despite annual pressure washing and scraping. It was also making the bottom rough, which can't help anything. Used the opportunity to switch to Micron bottom paint. After 11 months in the water I had to schedule a survey due to insurance nonrenewal after the hurricanes. I carefully inspected the bottom and it was perfect. Still good this year. I am hoping that the newer technology of bottom sealing and surface prep will get me at least another 25 years. Still, it pays to check when the boat is out of the water anyway.

[krush]

As a followup, the article in Power and Motoryacht talks about the benefits of using vinylester resin versus epoxy resin. Seems that vinylester presents a much better moisture barrier. I talked to the production guys last week at Hinckley and Legacy.. they advice this is the way to go.

I may be missing something, but I've heard that epoxy was the best. From worst to best (and cheapest to most $$$): polyester, vinylester, epoxy.

I'm pretty sure this is correct too---unless I'm remembering incorrectly

[Genesis]

Epoxy is both strongest and least-permeable.

It is also god-awful expensive compared to the other two.

[spartonboat1]

RE: the internet. Remember poor old Pierre Salinger who claimed a US Navy missile test brought down TWA Flight 800. He never lived that one down.

I happended to be home working 'virtual', when a CSPAN hearing covered the entire Flight 800 affair. Had some heavyweight witnesses, included former, now deceased, Chairman of the Joints Chief (oops, sorry, Joint Chiefs) of Staff, Navy Admiral Moorer (if memory is right), plus former military fuels and aircraft systems experts.

Not only Pierre, but Moorer's opinion was that a missile took down F 800.

They also had radar videos from that day, of various naval operations in the area, which was presented.

I thought they made a very good case that 800 was brought down by some type of ground to air missile. There was a lot of Naval exercise in the area, and there was talk of a friendly missile being mis-fired.

But a simple in-the-air on board explosiion was ruled out, because F800 was too high at the time.

So was Pierre right? Who knows. Much of the material presented seems to have been declared top secret or unavailable via FOIA.

Slow Sunday (between job jar tasks) post...

[MikeP]

Just don't do a blister job for the wrong reason. If you want to do it for cosmetic purposes, that's great. If you want to do it because you are afraid your Hatteras hull is delaminating and you are going to end up swimming...save your money.

[Steve Smith]

Epoxy is both strongest and least-permeable.

It is also god-awful expensive compared to the other two.

Epoxy paint cost will vary, depending whether you buy it yourself to do it yourself, or buy thru the Yard, with their discounts from a manufacturer's distributor and attendant markups to you, the customer.

It is true that polyester resins are inherently about a third the cost of epoxy resins, due to inherently simpler manufacturing chemical processes. All polyesters are made of esters and thus inherently decompose in water. Vinyl esters just do it more slowly. Epoxy resins don't. I have had a piece of my Fill-It Epoxy Filler under water in my lab since 1993 and it is unchanged.

Here's a benchmark for cost comparisons: If you walk into the Smith & Co. Factory store and buy a ten-gallon kit of High-Build Epoxy Paint, the cost as of August 2008 is $703, somewhat under our Suggested Retail. Shipping costs can add something onto that, but we have to start somewhere.

That ten-gallon kit, if put on in five to six coats (assuming a "coat" means 400 square fet per gallon), with some allowance for sanding, does about 800 square feet and provides an adequate barrier to stop gel-coat blistering, in concert with other measures.

Even allowing some for shipping costs, this material is very roughly a buck a square foot on the hull. A yard might mark that up some.

Other epoxy paints are in that same ball-park as regards pricing, although I must note that the waterborne 2-part epoxy paints are only about thirty percent solids, while the solvent-borne ones (including mine) are at least double that solids content. That means the cost of a waterborne 2-part epoxy paint would be at least double to get the same coverage and mil-build, and I can't speak to their barrier-performance.

Bottom line here is that the cost of haulout and labor normally eclipses the cost of materials, in my experience.

Further, it seems to be a common experience that the quality of labor is everything in getting a competent job done in a yard, and we all know competent people cost a competent price.

What have you found? Anyone got a fair-size Hatteras with an itemized yard bill?

[Westfield 11]

Do I smell a faint whiff of self-serving spam here? Sure sounds like promotion and advertising to me. I was wondering when he was going to get around to telling us the price.....