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Iroquois MkII
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Discussion Starter #1
Hi all,

I have recently purchased a 1969 Iroquois MkII catamaran, it should be showing up at the boatyard in Massachusetts early next week.

Now, the boat has no blisters, but I believe it has been in freshwater (Lake Huron) for most of its 40 years.

I'm nervous of what might happen when she's splashed into the saltwater after a season (or two or three), as blistering is much more prevalent in saltwater and this is a fairly old hull.

So, my question is, does it make sense to do a preemptive barrier coat? Or should I wait and worry about blistering if/when it happens?
 

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Telstar 28
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If you don't have a blistering problem now and the boat has been stored on the hard all winter, barrier coating might make sense... but you'd want to check the moisture content of the laminate first.
 

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my vote would be to do everything you can when its still out of the water, thru hulls, fair, paint, everything you can think of. then you have a few years years of not needing to worry about it.
 

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Telstar 28
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barrier coating a wet hull serves little purpose. :)
 

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Blister Detection Before Barrier Coat

Don't some blisters close up and disappear after the hull dries, making them difficult to detect? Pinhole blisters in particular.
I remember a Catalina on the hard that did this and the pinhole blisters were only seen when the hull was sanded completely clean of all bottom paint, and then they were hard to see. The holes were very, very small but there were a lot of them.
What would be the best way to handle that? Would a hammer sounding reveal anything? A moisture meter? Or is a close visual check the only way to find that kind of blister.
What would happen if you barrier coated without filling the blisters?
 

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See if you can survey some Iroquois owners. Much depends on the lay-up...

Hi all,

I have recently purchased a 1969 Iroquois MkII catamaran, it should be showing up at the boatyard in Massachusetts early next week.

Now, the boat has no blisters, but I believe it has been in freshwater (Lake Huron) for most of its 40 years.

I'm nervous of what might happen when she's splashed into the saltwater after a season (or two or three), as blistering is much more prevalent in saltwater and this is a fairly old hull.

So, my question is, does it make sense to do a preemptive barrier coat? Or should I wait and worry about blistering if/when it happens?
and the resins used. If it was a Gemini, it would be at very high risk. If it were a Stiletto it would be at no risk. You made to troll British sites.

But SD is dead on if you can't get good info. If the hull is dry, you do have to strip it, but after that it's easy.
 

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I asked a similar question of a boatyard expert in CT...but it was about a new boat..should I use barrier coat under the Micron antifoul?

He said that the blistering is more of a problem in warmer waters and that using the Micron bottom paint was fine....which I am glad of because that would have been a LOT more work.

Not sure if that pertains to an old boat just the same, but the guy seemed to know what he is talking about....has been in the brokerage biz for many years.
 

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Iroquois MkII
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Discussion Starter #8
The hull is reasonably dry, it's been on the hard all winter. However on the hard in Canada means several feet of snow surrounding it... but that melted a few weeks ago.
 

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Telstar 28
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In that case, I would go ahead and strip the bottom and barrier coat it. :)

The hull is reasonably dry, it's been on the hard all winter. However on the hard in Canada means several feet of snow surrounding it... but that melted a few weeks ago.
 

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Owner, Green Bay Packers
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If a boat built in 1969 was going to blister it'd have likely got around to it by now. Paint it, sail it.
 

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ASA and PSIA Instructor
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Sounds like a fun boat.

If you are going to sail it seasonally in new England, and the boat has paint on it, I use it a season and see how it comes out of the water. No blisters and you are good. Blisters - and you have to go through the nasty, long job of removing all the bottom paint and doing a barrier coat. I'll bet your bottom will look fine forever, don't go looking for work and expense that may be completely un-necessary.
 
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