Barrier Coat or Not?

[Will Fish]

So I know there are thousands of threads out there on this topic but here is another. I have a 1974 21' cuddy cabin. The boat is kept in NY salt water 6-8 months a year and kept on blocks during winter months. There is roughly 8 coats of bottom paint which I plan on stripping this year and putting some fresh paint on I'm on the fence about barrier coating. Last time the hull was stripped down, there were no blisters at all. I've read "if it hasn't happened yet..." as well as "since its stripped...might as well do it." I really don't know which way to go with this one. I see both points, and I do not want to have added unnecessary weight (the boat is a tank for a 21 footer). I also plan on keeping this boat for a while and do not want future damage. What do you guys think?

 

[Slip Away]

Re: Barrier Coat or Not?

I agree with the " since it's stripped.... might as well do it" . And since you plan on keeping it, and it is 40 years old, it seems logical to protect it with a barrier coat.

 

[Home Cookin']

Re: Barrier Coat or Not?

I think I'd not strip the old paint and just paint on top of it.

 

[Will Fish]

Re: Barrier Coat or Not?

Home cookin' - it's gotten to the point of chips and loose paint all over the bottom. I need to strip the bottom completely to obtain a smooth surface. Plus the added weight (roughly 25lbs a gallon x approx 8 coats = 200lbs of added unnecessary weight)

I definitely want to start at the gel coat, but not sure if I should barrier coat the bottom or just throw 2 coats of paint using a different color as my base coat.

 

[arks]

Re: Barrier Coat or Not?

This is a no-brainer.
Get all the old paint off the hull and do the epoxy barrier coat. If applied correctly (10 mils thick) it'll make the hull impervious to water intrusion- unlike the original gelcoat. Overcoat the new barrier coat with your choice of bottom paint and you're good to go with no worries.

 

[ondarvr]

Re: Barrier Coat or Not?

Lets complicate this a little more.

If the boat has been sitting for that length of time in the water every year, then the laminate has absorbed a good deal of water already, and it hasn't blistered yet, at least that you have noticed. Whether it will in the future is an unknown. Removing all the old paint and putting on a thick enough layer of epoxy will make a very good water resistant coating (nothing is waterproof). This will help to prevent water from being absorbed in the future, but also locks in any water already in the laminate, so while new water may not contribute to blistering, the water already in there may already be (an unknown).

In a full blister repair job the gel coat and any blistered laminate is remove down to good glass, then it is allowed to dry out as much as possible before rebuilding the surface with epoxy and possibly more glass, just depends on how much material was removed. Without following these steps the likelihood of failure is higher. Water already in a laminate and continuing to cause blisters is a major reason for even otherwise good blister repairs to fail.

So while putting on a barrier coat isn't a bad idea when a hull is new, or hasn't been in the water for long periods of time, on an old hull that's been moored for months on end it may or may not be a good idea.


If it was mine and I was leaving it in the water and had removed all the old paint, I would probably use a barrier coat.