I have seen a 1999 280SS with the blister rash seasonally slipped in fresh water. It is a rarity but can happen. My 330SS had a few just starting, but I treated them and barrier coated the bottom.

If you are going to keep the boat in the water seasonally, it is best to provide some protection below the waterline.

When you say "barrier coated" the bottom...this is essentially bottom paint, or a bottom paint system, correct?

I really hate the idea of "bottom paint" on this type of boat. Unless the bottom paint would be basically indistinguishable from unpainted gelcoat. Don't think that exists...

My 292 is trailer kept, will sit in the water overnight here an there but never for extended periods of time. I have just started using collinite within the past few years. I too have like the results.

Yeah, until the blisters, the only downside to keeping my boat in the water has been the slight staining of the gelcoat over time. My weekly ritual basically involves scrubbing the boat top to bottom quite thoroughly (I anchor in 4 ft of water that allows very thorough bottom cleaning). The collinite is the best product I've found that removes the slight discoloration with ease. I've never tried any other product on my Formula, but on a previous Sea Ray, even products marketed towards gelcoat color restoration were not effective. On the Formula, I've never even considered the need to use anything else as I was so delightfully surprised by the results from the Collinite. When I first discovered how effortlessly the Collinite removed the staining, I thought to myself...."wow, Formula must use some really good gelcoat...."

I would trade some slight discoloration for my blisters any day....

I'll have to post a pic of my diaper-rash 271. The hull sides shine like mirrors otherwise. I really wish there was a legitimate fix. Meanwhile, I try to convince myself that, "hey, maybe it makes the boat a little faster and more efficient...kinda like a golf ball through the air". Most 271's have one step. Mine has 10,000 or so

Don't have any Collinite stories. Just asking. Gel is porous and will let water through if not waxed. Hull cleaning will strip the wax off and wax must be redone. Glazing and waxing keep the gel sealed. Below the water line there is a constant pressure of about 1 psi trying to force water through. Sealing gel is important.

Yes there is a white bottom paint that is very cosmetic and not easy to see.

listen to this guys he has seen and fixed several formula's with this issue...

May I ask...in general, what are the steps to fix? Is all gelcoat on the bottom removed and then re-gel coated or re-painted? Any additional steps that would make the hull more "blister proof"?

In my case, since the blisters do come up the hullsides and intersect graphics, I would think the whole hull of the boat would need re-painted. And then, graphics would need to be painted.

http://lmgtfy.com/?q=how+to+fix+boat+gelcoat+blisters

Really depends on how many, how big and the depth of the blisters, best remedy I know of is to strip the bottom, fair it in, prime with epoxy primer meant for below the waterline, as a barrier coat, gel over that or paint your choice. I prefer to gel for its durability and the fact you can "work" minor imperfections

Regarding number of blisters, there are literally 1000's of them...each around the size of a pin head. I suppose its hard to assess the depth without stripping first.

My biggest challenge, I think, will be finding someone capable and interested in doing a good job. Again, if anyone has anyone they would recommend in the SE Michigan / NW Ohio area, I'm all ears.