Bottom Paint / Barrier Coat

[DLT]

I have stored my boat on a trailer since new, so have not applied either.

But, I will be storing the boat in the water on a fresh water lake this next season and just wanna get a sense for what others are actually doing.

I know there are issues with cold v. warm water, and that some areas are just plain worst than others, but...

Yes, I realize that all you salt water guys and trailer guys are being left out... Sorry, but there are just not enough poll options to work it all in...

P.S. I really have no intention of this being a rehashing of the subject, other than just an actual practice poll... But, if you have new information to add, or just wanna link to relevent information/discussion, such that this becomes a repository for the future, feel free...

[jim nolan]

I have a 1999 26x. I have a slip on a fresh water lake in upstate N.Y. The second year, I had the boatyard put three coats of bottom paint that is supposed to sluff off, and keep the bottom free of marine growth. It cost about a thousand dollars. I don't know good that worked, cause the boat was always slimy when they pulled it out to power wash it, at the end of the season. If I had to do it again, I would have left that nice smooth bottom alone, and power wash it, or acid wash it at the end of the season. I always ask the yard to check for blisters at the end of the season. Nothing yet, Thank God. jim nolan

[Scott]

Hey DLT, you know where I live and where I slip. In less than a season I get about a 1-2" beard on my depthfinder. Its not coated. The rest of my boat stays squeeky clean. I use 1 gallon every 2 to 3 years. When the boat sits it get a little green fuzz on it but as soon as you start motoring out of the marina, it falls off.

The tops of my Rudders, which point down when slipped and raised, are permanently stained just from the little splash they get.

[Catigale]

Four seasons on the Hudson (upper river, where it is straight fresh water) without barrier or bottom paint

Art Reiders at Havencraft talked me out of Bottom paint - if you werent going to be in salt for more than a week or so then he said dont bother.

I wax it at beginning of each season. I use a power washer (electric Karcher) at the end of season and sometimes when I have it out for trailering

Ive noted that the fresh water- salt water cycle seems to kill any slime that attaches itself to the hull.

No blisters, a few scratches where Ive hit submarines - revealing the slower blue hull that Macgregor puts on every boat under the white hull. I put 5200 on those each season if the old stuff comes off.

[norbert]

I allowed me to vote "both" although "surprise" is on the baltic sea since 3 years. but #1 the baltic sea has a very low amount of salt and so should almost be considered as fresh water - at least in relation to the risk of osmosis. and #2 my boat was 5 years on inshore lakes before.

I recall that fresh water is more likely to induce osmosis on grp boats than salt water (as the molecules are smaller). I highly recommend to protect you property by a epoxy coat if you leave it more than a few weeks in the water. osmosis is a severe structural dammage and cannot easily been cured. a properly painted osmosis protection ist very durable and should least about 10 years.

on the lakes I had no coat for the first 2 years but was seriously warned by a boat buider about the risks i go. I then applied a epoxy barrier coat and a nontoxic antifouling. the latter did not work on the baltic sea (had lots of barnacles on the hull) so I changed to a common antifouling 2 years ago. no problem since.

[wtelliott]

I applied both bottom paint and a couple coats of barrier paint last spring. I slip in Lake Superior (In my opinion the cleanest of the Great Lakes as well as the coldest). Where the bottom was painted I had no algae at the end of summer, but on the rudders where I had not applied a bottom coat, there was a heavy layer of algae. Had some scrubbing to do...
The cost was reasonable and it took me a week of evenings and a Saturday to prep and apply. I think it was worth it.
Can't wait till SPRING!!!

[KaiSchuler]

I voted both because I intend to apply both Interprotect 2000 and Micron CSC for the coming season. My boat will be docked in the Reefpoint Marina in Racine, Wisconsin, and seems to be reasonable insurance against potential severe hull damage.

Will let you guys know at the end of the season how it worked out. Any specific suggestions for this part of Lake Michigan?

Best regards,
Kai

[Frax]

Why do you put a barrier coat on??
Why do u use epoxy treatment against osmosis....

i cant see any any benefits from osmosis treatment on just one side.. and how do you treat the inside of the ballast tank??

if your in the water allot i guess you have water in the ballast tank.. or a high level of moisture. and you will get osmosis from the inside...


/Fred

[Frank C]

... i cant see any any benefits from osmosis treatment on just one side..
and how do you treat the inside of the ballast tank?

This is a frequent question due to a common misconception. Blisters are NOT caused by water penetraing the fiberglass. Water does not seep through the layers of hull fiberglass, either from ballast tank to the exterior, nor the reverse. The hull simply does not leak to that degree. Otherwise, every marina would have hundreds of forgotten or ignored FRP boats resting in the mud. Rather, every marina has thousands of hull blisters that destroy the gelcoat, but don't sink those forlorn vessels.

Blisters are tiny separations between gelcoat and underlying fiberglass, caused by the water pressure of the boat's weight floating in a slip. They don't happen in only a week, it takes multiple weeks or months of pressure. (Think of a child's helium balloon that very slowly seeps & shrinks.)

Just as importantly, blisters spread along a hull, not through it. Once admitted under the gelcoat, the water seeps along the exterior layer of glass, between the glass and the gelcoat. Blisters are the result of water seeping through the gelcoat, not seeping through the fiberglass.

• (Yes, a little bit oversimplified ... after a year(s) of this exposure, any given hull might well become 'somewhat' waterlogged or soggy, especially if the FRP was laid defectively. But there are no overwhelmingly widespread indicators that Macgregor's process is faulty ... in fact, the opposite seems true.)

Blistering can be exacerbated by an imbalanced fiber-to-resin mixture in the outer layer of fiberglass. This is the layer adjacent to the gelcoat, and when the fiber mat is not fully saturated with resin, it leaves a void that can more easily admit (suck-in) water under pressure. Rarely will the several layers of hull fiberglass just happen to have this defect in exactly the same spot, which might permit water to migrate between layers rather than running ALONG the single, outer layer (where the pressure is greatest). There's relatively little pressure within the ballast tank, but if my boat was slipped, I would keep the tank empty, for many other reasons.

Finally, this nice and neat, scientific-sounding theory is just one, over-simplified explanation, among many. It's probably correct in most respects, but not comprehensive as to ALL potential factors in osmosis of boat hulls. If you're really interested, you can spend an entire weekend reading about this stuff on the internet, and David Pascoe's website (see articles, rt. column) can occupy you for that whole Saturday!

[kmclemore]

I'll repeat a posting I did on a *much* earlier discussion of this subject, now long buried in the depths of this forum...
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I strongly recommend the following book on the subject.... I'd dare to say it is the definitive manual on blistering of glassfibre, as well as the proper construction and repair of boats. I'm fortunate to know a bit about glassfibre, having worked for Lotus Cars, Ltd., for whom I did a considerable amount of custom moulding in their Elan, Europa and Esprit lines.

Click HERE for the book, "OSMOSIS & Glassfibre Yacht Construction" by Tony Straton-Bevan.

The book, in fact, has an entire chapter devoted to the causes and cures of osmotic blistering in GRP, and another whole chapter on how to avoid it.

(other reviews/notes about this book are HERE and HERE)

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(Editor's note... I see that Amazon now has this book on sale... fer cheap!)

[fsmith]

Is it possible for blisters to form just under the barrier coat. It seems that when i sand these areas, the are smooth before getting to the gelcoat! Does anybody know, or do i really have gelcoat blisters?