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Discussion Starter #1
How critical is a barrier coat? Probably more to the point, what does a barrier coat do?

If my boat has a non-cored hull... i.e. solid glass. do I need a barrier coat or can I just prime and paint. It will practically double my expense to have a barrier coat placed so I would rather not...But I want to do what is appropriate.

BTW she will be kept on saltwater 24-7
 

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It's not necessary, but.......

If you leave the boat in the water 24/7 for many months, AND it is a Glass/Polyester resin boat, at some point, the likelihood of you getting blisters on the boat is high.

If you plan on parking your boat in the salt water for many months, a barrier coat is probably a good idea.

DrB
 

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Paloma is 30 years old and has been in salt water since 1979, coming out about every three years for a bottom job (annual quick hauls for power washing and check/replace zincs). Solid glas hull, never had a barrier coat and never needed one.
 

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That is what I have been suspecting. I thought blisters only happened on cored hulls where the fiberglas delaminates off the coring. I guess you could also get small delamination between fiberglass layers too but that would be difficult with a solid resin hull.
 

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Blisters and delamination are two different things... any fiberglass hull—cored or solid—can blister, where water has gotten into the laminate via osmotic pressure and created blisters under high pressure that are filled with a fairly acidic substance. However, cored hulls can also delaminate, where water has gotten into the core area and either separated the foam from the laminate skins or rotted the balsa core material.

That is what I have been suspecting. I thought blisters only happened on cored hulls where the fiberglas delaminates off the coring. I guess you could also get small delamination between fiberglass layers too but that would be difficult with a solid resin hull.
 

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If a boat shows no blistering from prior use, and is going to continue that form of use, then in my opinion, a barrier coat is not necessary. The purpose of the barrier coat is to prevent blistering...if an experienced boat has no history of blistering, why bother?

Note that being in warm water for 12 months a year is heavy use. If you were taking a Northern boat to Florida for the first season, the risk of blisters would increase dramatically from its prior use, I'd do the barrier coat then just to be safe. But if the boat has been in such waters in prior years, what's to change?
 

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Consider what it cost to do a barrier coat, then consider what it will cost if a blister repair job is in order, I think you'll find it an easy decision ;)
 

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Consider what it cost to do a barrier coat, then consider what it will cost if a blister repair job is in order, I think you'll find it an easy decision ;)
What is the cost of a blister repair job? If blistering starts, is it just one or two, or do a bunch break out at once?
 

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What is the cost of a blister repair job? If blistering starts, is it just one or two, or do a bunch break out at once?
The cost of a blister repair job will vary as widely as the blistering conditions that might occur on a boat - from a few inconsequential dimples safe to ignore to a fully cratered, water saturated bottom needing a peel and recore repair. Read through Hull Blisters on Boats and Yachts - by David Pascoe, Marine Surveyor if you want to understand some of the causes and impacts of blisters.

Again, if the boat has been used where and how you plan to use it, inspection of the boat will tell you it's suspectability to blistering.
 

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I am not going to address blisters or delamination, both are be caused by water intrusion. Gel coat is porous, fiberglass laminate is porous enough to wick and trap water.

Barrier Coat will help keep your boat from soaking up water over the season and adding weight. IT WILL MAKE YOU SAIL FASTER, because your boat will weight less than a boat without barrier coat. Ask any hard core racer or a travel lift operator. They know a boat weighs more at the end of the sailing season then they do at the start of the season.
 

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what exactly is the cost of a barrier coat though? Assuming you do have a boat down to its bare bottom (which sounds like you might) - it is pretty much a cost of about 4 gallons of barrier coat epoxy (such as Interprotect) and time rolling paint. Not all that much fun, but not the most difficult job in the world either and the price is in some hundreds.

The fact that an old boat does not have blisters does not mean that osmotic process is not ongoing. Polyester resin is dissolved in water, in particular salt water and in particular salt warm water - just slowly. Boats with less permeable gelcoat tend to get blisters, while boats with more porous gelcoats tend to simply lose resin from outer layers of laminate. It is a long process but by no means good for a boat either way. It is worth comparing the benefits vs. cost and intended use of the boat of course - if you don't plan to keep a boat for a long time, then it probably is not worth doing. If you do, however, and have the bottom properly prepared - I think applying barrier coat is cheap relatively to future potential issues.

Then again - I am the guy that actually spent 3x the book price of my boat on maintenance and improvements in the last few years :) So it may be just me.
 

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The real issue is drying out a boat that IS ALL READY wet which is pretty MUCH not going to happen unless you have the bucks to put in a heated building for a really long time

We did get a few weeks of 10% Rh but that was really rare
 

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The fact that an old boat does not have blisters does not mean that osmotic process is not ongoing.

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Then again - I am the guy that actually spent 3x the book price of my boat on maintenance and improvements in the last few years :) So it may be just me.
That's right, if the water has already gotten into the gel coat, there may not be blisters. But water does not come out as easily as it went in. I have read that once inside a chemical reaction takes place where the woter bonds with something else (don't remamber the dtails) and becomes bigger, and therefore can not get back out the way it came in.

Given this, I would be surprised if the boat could dry out so easily.

But this argument cuts both ways. You can argue that if the boat is not going to dry out (at least not much) the barrier will at least keep more from getting in. Also, if the boat is not going to dry out, you can argue that the barrier won't keep it out.

My boat would need 4 gallons of Interlux 2000e, at a cost of $300.00. Of course, I would also need rollers, pans, and all the other associated junk. And I would need stripper at ~ $30 per quart. Plus these 4 gallons go on over about 5 coats, with at least 2 to 3 hours between coats, after a lot of stripping and sanding has happened.

Alternatively, I can lightly sand the Interlux micron paint that is on it already and recoat it with 2 gallons of Interlux Micron 66. Does not matter what the paint cost, because that has to go on anyhow.

So the decision is, is it worth ~ $400 and many hours of stripping and sanding to put a barrier coat onto a boat that's > 32 years old and shows no signs of blistering?

I don't know, but probably not. I can't decide. If the boat was already down to gel coat for some reason, easier decision.

Also, I am already in to this boat for more than I wanted by far, but it's a boat. That's what happens. If blisters occur, I would probably learn to repair them myself, then do a barrier coat. But who knows.
 

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But this argument cuts both ways. You can argue that if the boat is not going to dry out (at least not much) the barrier will at least keep more from getting in. Also, if the boat is not going to dry out, you can argue that the barrier won't keep it out.
Actually you can't really argue this as Interlux recommends a moisture content below .25% before the application of IP2000E. Applying a barrier coat over anything with a higher reading is futile and can cause future issues..

My boat would need 4 gallons of Interlux 2000e, at a cost of $300.00. Of course, I would also need rollers, pans, and all the other associated junk. And I would need stripper at ~ $30 per quart. Plus these 4 gallons go on over about 5 coats, with at least 2 to 3 hours between coats, after a lot of stripping and sanding has happened.
It may not actually need that much a gallon kit will go around my CS-36 about 1.5 times so if applied right you may be able to get away with less.

Alternatively, I can lightly sand the Interlux micron paint that is on it already and recoat it with 2 gallons of Interlux Micron 66. Does not matter what the paint cost, because that has to go on anyhow.
If your micron is not showing any signs of your tracer coat then DON'T paint it. This is the biggest mistake people make with ablatives. Over application of ablative pains will lead to flaking and peeling. Furthermore the Micron line of paints does not start ablading until 7-8 knots!! If you want to use an Interlux ablative on a monohull use ACT as it will begin ablading at 2-3 knots just as most of the Pettit paints do.

On a sailboat you want a low ablation speed and the Micron is NOT a low speed ablative in terms of sailboats. As for Micron 66 make SURE your vessel will NEVER spend any more than a minute amount of time in even brackish water. Micron 66 MUST be is salt water 100% of the time. Fresh or brakish water will RUIN Micron 66!!!!

So the decision is, is it worth ~ $400 and many hours of stripping and sanding to put a barrier coat onto a boat that's > 32 years old and shows no signs of blistering?

If your boat was already stripped and dry then it's a no brainer other wise I'd say paint it or better yet leave it if you have no tracer color showing...
 

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Actually you can't really argue this as Interlux recommends a moisture content below .25% before the application of IP2000E. Applying a barrier coat over anything with a higher reading is futile and can cause future issues..
Ah, okay I stand corrected, thanks. I guess in this case, if the moisture content is that low on a 32+ year old sailboat, there is no need for the barrier coating. If the moisture content is higher, well I can;t do it anyhow ;)

If your micron is not showing any signs of your tracer coat then DON'T paint it. This is the biggest mistake people make with ablatives. Over application of ablative pains will lead to flaking and peeling. Furthermore the Micron line of paints does not start ablading until 7-8 knots!! If you want to use an Interlux ablative on a monohull use ACT as it will begin ablading at 2-3 knots just as most of the Pettit paints do.

On a sailboat you want a low ablation speed and the Micron is NOT a low speed ablative in terms of sailboats. As for Micron 66 make SURE your vessel will NEVER spend any more than a minute amount of time in even brackish water. Micron 66 MUST be is salt water 100% of the time. Fresh or brakish water will RUIN Micron 66!!!!
Wow, twice on the phone with Interlux and they never mentioned the minimum speed requirement. But they did tell me that Micron 66 will ablate just sitting there, smoothing itself just sitting in its slip. They said the CSC and the other one won't do that.

My paint is in horrid condition. There are spots where the paint has flaked off in two inch chips, and another big section where it just seems to be very thin. Perhaps this more than just age. I am not sure exactly what "brackish" water is. My boat lives in a slip in Warwick, RI, and is sailed on the Narragansett Bay. The marina is a bit inland (Dickerson's). I know it rains of course, but I don't know how much fresh water hangs around, although I would think none. But it only spend a few weeks there, before that it was at the EG Yacht Club. I don't think either place has any fresh water mixing in in any great quantity.
 

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Hm, I guess there is some brackish water here in Narragansett Bay. A little googling found:

Winds and Tides

Scientists measure the salt content of tide water in parts per thousand. Salinity not only increases buoyancy for those whose swimming consists of floating lazily at the surface like ocean sunfish but also has much to do with the kinds of plants and animals that live beneath the surface. The Bay is salty but not overly so, becoming more and more brackish toward its head, where rivers and streams provide a freshwater mix. The Blackstone, Woonasquatucket, and Moshassuck at Providence, the Palmer River in Barrington, the Taunton at the head of Mount Hope Bay, the Pawtuxet marking the boundaries of Cranston and Warwick, and the Potowomut River in North Kingstown all play a part in reducing salinities in adjacent waters. At its entrances and for a considerable distance upward, the Bay contains water with salt content of 30 to 32 parts per thousand. The proportions drop off dramatically inside the river mouths. Bottom waters are generally more salty than the water at the surface, and the water of the East Passage is the saltiest of all.

And also:

http://www.nbnerr.org/Content/SiteProfile08/10_Chapter 8_Estuarine Habitats.pdf

That last document describes the various habitats on the Bay where various creatures grow in varying degrees of salinity.

Well if nothing else I am learning stuff :(

Okay since the PO told me he knows that Interlux Micron is on there and he thinks it is 66, I know there is some Micron. All of it says suitable for high speed, so if I am not going to use Micron then I need to strip it all off anyhow. If I have to strip it all off anyhow I'll measure the moisture content once I do that and decide about a barrier coat.

Then I'll go back to my original plan and apply the hard, performance racing paint. The Regatta is on sale at Defender right now, and VC Offshore is not that much more expensive.

I'll make a call to Interlux tomorrow to confirm that the Micron other than 66 won't ablate below 8 knots and if they say it won't, then the boat gets the full treatment. If they say it will, then I'll probably go with CSC.

Why can't anything be easy? Because I always make it more complex that it needs to be! :D

Hm, I stole the thread. I'm really sorry :(
 
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