barrier coating and blisters

[inconnu]

Another barrier coating question. I just bought a '96 Voyager and was surprised to read in the manual the statement that if the boat is to be left in the water more than a few days at a time, it should be barrier coated. I would have assumed that a premium builder like Grady would have applied construction methods and materials that prevent blistering. I have owned numerous fiberglass boats of much lesser builders, some of which stayed in the water year around here in Alaska, and the others for months at a time and never had blisters. I won't keep the Grady in year around but hope to keep it in for a couple of months during the summer. The boat has a perfect bottom that has never been painted.
Are blisters really a problem with 90s vintage Gradys, and should I spend the money now to get it barrier coated, while there still is no paint, or is it a non-issue in my situation?
Thanks for any comments, particularly from owners in cold water regions.

 

[ctcbtr]

I have a 91 252gt with 20 yrs bottom paint no barrier coat and is in water year round , never had a blister, BUT next year when I blast the bottom I will for sure put barrier coat on it before bottom paint

 

[uncljohn]

I think in general it depends on the use of polyester epoxy resin (old) vs. vinylester resin (new), where polyester is prone to osmosis. I don't know when Grady changed, but as the owner of a 1988 Grady, I definitely had blisters on a boat that sat in water all year (previous owner) and I definitely barrier coated mine after it was soda blasted.

 

[seasick]

Barrier coats will help prevent blisters but it won't fix existing ones.

 

[uncljohn]

Barrier coats will help prevent blisters but it won't fix existing ones.

Yeah, I left out the details of grinding, drying, filling, and faring between "I got mine soda blasted" and "I applied a barrier coat" :-|