I sail a 24 foot fibreglass boat on the Great Lakes for about six months a year. The boat is stored outside on a trailer during the winter. Given that I would have to strip off the bottom paint etc., is it worth going through this effort for the sake of applying a barrier coating system?
Do these sytems actually do what they are supposed to do ie prevent or reduce the likelihood of osmotic deterioration? Many boats here have had these coatings applied and more have not.
Could you please share your thoughts or opinions about barrier coating systems?
Lyman
Barrier Coating Systems
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Tim
- Shipwright Extraordinaire
- Posts: 5708
- Joined: Tue Apr 01, 2003 6:39 pm
- Boat Name: Glissando
- Boat Type: Pearson Triton
- Location: Whitefield, ME
- Contact:
My opinion is: don't waste your time and money. I feel that barrier coats are engineered more as a repair system for boats already damaged by osmostic blistering rather than as a prevention device. I believe that barrier coating is completely unnecessary unless you already have blistering. I think boatyards and barrier coat manufacturers are enjoying a cash cow based on overplayed hysteria over an issue that, while real, doesn't apply across the board by any means.
Few boats in the north develop blistering, ever. With as much time (or more) out of the water as in, there's plenty of time for laminates to dry out, etc. Plus, not all laminates are necessarily prone to blistering in the first place. And some blister for other reasons not related to osmosis--but that's a whole other topic.
Boats that previously showed no evidence of osmosis or blistering, that have been "preventative barrier coated" have been known to suddenly develop blisters. All laminates absorb moisture. As long as there's an avenue for that moisture to also disappear, blistering is less likely to occur.
I'm also pretty sure that fresh water presents less of a problem for blistering (or even nonexistent, but since I deal pretty much only with salt water, I'm not sure). As I understand the chemistry behind it all, it's a reaction between styrene in the polyester laminate and the salts in the water. Now, "salts" being a generic term and all, it's possible that certain "salts" may exist in some fresh water, which is why I avoid any absolutes here. Still, it's generally considered to be a salt-water problem. This brief paragraph also represents the totality of my knowledge of and interest in the chemical process behind blistering. Since it's virtually a nonissue where I live and work, it's never been important enough to delve into further.
Few boats in the north develop blistering, ever. With as much time (or more) out of the water as in, there's plenty of time for laminates to dry out, etc. Plus, not all laminates are necessarily prone to blistering in the first place. And some blister for other reasons not related to osmosis--but that's a whole other topic.
Boats that previously showed no evidence of osmosis or blistering, that have been "preventative barrier coated" have been known to suddenly develop blisters. All laminates absorb moisture. As long as there's an avenue for that moisture to also disappear, blistering is less likely to occur.
I'm also pretty sure that fresh water presents less of a problem for blistering (or even nonexistent, but since I deal pretty much only with salt water, I'm not sure). As I understand the chemistry behind it all, it's a reaction between styrene in the polyester laminate and the salts in the water. Now, "salts" being a generic term and all, it's possible that certain "salts" may exist in some fresh water, which is why I avoid any absolutes here. Still, it's generally considered to be a salt-water problem. This brief paragraph also represents the totality of my knowledge of and interest in the chemical process behind blistering. Since it's virtually a nonissue where I live and work, it's never been important enough to delve into further.
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Shark
- Skilled Systems Installer
- Posts: 178
- Joined: Thu Apr 17, 2003 4:27 pm
- Boat Name: Scoot
- Boat Type: Shark 24
- Location: Burlington, Ontario
- Contact:
Tim,
"I think boatyards and barrier coat manufacturers are enjoying a cash cow based on overplayed hysteria over an issue that, while real, doesn't apply across the board by any means. "
My sentiments exactly. I hesitated to use the term "scam" but to a large extent it's "caveat emptor" all over again!
I have heard horror stories about this subject locally and actually saw one boat after the bottom was peeled. It was still soaking wet inside and the surveyor I spoke with was not optimistic about the future prospects for that boat. However I was not aware of that boat's history. It may have come up from the south. Who knows?
When I stripped the bottom of my previous boat I discovered some small voids or blisters which I filled and forgot. I intend to do the same with any I might find on the present boat.
Lyman
"I think boatyards and barrier coat manufacturers are enjoying a cash cow based on overplayed hysteria over an issue that, while real, doesn't apply across the board by any means. "
My sentiments exactly. I hesitated to use the term "scam" but to a large extent it's "caveat emptor" all over again!
I have heard horror stories about this subject locally and actually saw one boat after the bottom was peeled. It was still soaking wet inside and the surveyor I spoke with was not optimistic about the future prospects for that boat. However I was not aware of that boat's history. It may have come up from the south. Who knows?
When I stripped the bottom of my previous boat I discovered some small voids or blisters which I filled and forgot. I intend to do the same with any I might find on the present boat.
Lyman
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Dave, 397
Yeah, it is a tricky subject, for sure.
It has taken almost a year on the hard before my moisure meter reads pretty much uniform over the hull both above and below the waterline.
Since I did so much grinding/fairing/fairing by grinding on the bottom with the vertical polisher and DA, I opened up a gazillion pinholes and ended up with no gelcoat in a few places. That given, I feel like I am pretty much committed to a barrier coat of some sort.
Check out the info and products at Progressive Epoxy Polymers ( www.epoxyproducts.com) . The site is primitive and takes some effort to figure out the navigation, but it's well worthwhile. The fellow sells all manner of epoxy products and urethane coatings...all industrial stuff that by reports of a fellow who has been using it is much nicer than the "marine" products and costs less, too--including frt. in most cases!
PEP also sells an FDA-approved epoxy barrier coat product for use in potable water tanks, and a nuke-plant certified barrier product that should really kick butt on a boat bottom.
I ended up with 5 gallons of Jeffco hi-density epoxy facecoat, and it has very favorable specs...so I'll probably use it.
FWIW, the Triton spent most of her life in the Columbia River, but I stil had about a half-dozen honkin'-size blisters. They did appear, though, to have come from INSIDE. I've had several people comment that boats which have/have had a wet bilge for some time tend to have more ofthis than boats which have not. I'm going to lay a barrier coat inside the bilge, as well.
The consensus I've gotten so far is that having a dry hull--no matter how long that takes--is key to making a barrier coat work out for you without unwanted problems. A pinless moisture meter is not too costly (I think I paid about 150.00 for mine a few years ago) if you will have other uses for it, but if not you may be able to borrow one from someone. I would definitely make use of it before barrier coating the hull.
Dave
It has taken almost a year on the hard before my moisure meter reads pretty much uniform over the hull both above and below the waterline.
Since I did so much grinding/fairing/fairing by grinding on the bottom with the vertical polisher and DA, I opened up a gazillion pinholes and ended up with no gelcoat in a few places. That given, I feel like I am pretty much committed to a barrier coat of some sort.
Check out the info and products at Progressive Epoxy Polymers ( www.epoxyproducts.com) . The site is primitive and takes some effort to figure out the navigation, but it's well worthwhile. The fellow sells all manner of epoxy products and urethane coatings...all industrial stuff that by reports of a fellow who has been using it is much nicer than the "marine" products and costs less, too--including frt. in most cases!
PEP also sells an FDA-approved epoxy barrier coat product for use in potable water tanks, and a nuke-plant certified barrier product that should really kick butt on a boat bottom.
I ended up with 5 gallons of Jeffco hi-density epoxy facecoat, and it has very favorable specs...so I'll probably use it.
FWIW, the Triton spent most of her life in the Columbia River, but I stil had about a half-dozen honkin'-size blisters. They did appear, though, to have come from INSIDE. I've had several people comment that boats which have/have had a wet bilge for some time tend to have more ofthis than boats which have not. I'm going to lay a barrier coat inside the bilge, as well.
The consensus I've gotten so far is that having a dry hull--no matter how long that takes--is key to making a barrier coat work out for you without unwanted problems. A pinless moisture meter is not too costly (I think I paid about 150.00 for mine a few years ago) if you will have other uses for it, but if not you may be able to borrow one from someone. I would definitely make use of it before barrier coating the hull.
Dave
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Tim
- Shipwright Extraordinaire
- Posts: 5708
- Joined: Tue Apr 01, 2003 6:39 pm
- Boat Name: Glissando
- Boat Type: Pearson Triton
- Location: Whitefield, ME
- Contact:
Planning on adding some spent uranium to your ballast cavity, Dave? ;<)Dave, 397 wrote:...nuke-plant certified barrier product that should really kick butt on a boat bottom...
And now, a few words on moisture meters in general, brought to you by that annoying little voice in my head:
Anyone using a moisture meter should be aware that, while useful, they have serious limitations and can provide misleading, false, or inaccurate results. Use with care and proper knowledge, and keep all caveats in mind. Many surveyors, myself included, have found the meter's results to be enough open to interpretation that we only use them as a means of confirming the more accurate results obtained by the seemingly-archaic percussion sounding.
That said, monitoring the dryout of a peeled or blistered hull is indeed one of the more potentially handy and accurate uses of a meter. Just beware that if you've never used a meter before, it's easy to misinterpret or over rely on the results. A dry hull is indeed important when repairing blisters, or applying barrier coat. Completely drying a badly saturated fiberglass laminate can take years. Rinsing frequently with water actually accelerates the drying process in these cases.
But all this is getting way off the original topic.
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David
David Pascoe, a marine surbeyor has a great website with a lot of excellent information about hull blistering. Three articles are shown below:
http://www.yachtsurvey.com/moreonblisters.html.htm
http://www.yachtsurvey.com/BlisterRepairFail.htm
http://www.yachtsurvey.com/WetLaminate.htm
David
http://www.yachtsurvey.com/moreonblisters.html.htm
http://www.yachtsurvey.com/BlisterRepairFail.htm
http://www.yachtsurvey.com/WetLaminate.htm
David
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Dave, 397