Blisters!! Peeling or Sandblasting??

[teneicm]

We just had a prospective 45' catamaran surveyed and the 20 year old hulls have significant blistering everywhere. The blisters are primarily small (about 1/2 inch), but in some areas are densely packed together, so close to 50% of the surface area is blisters.

The surveyor is recommending a peel job. The broker thinks a sandblasting is sufficient as the blisters are small. I'm assuming that the sandblasting would still leave most of the gel coat on, but am not certain?

When is one technique better than the other? What are the ball park respective costs? Boat is in New England.

Thanks- Matt

[ohdrinkboy]

Have no idea on the cost of your cat, but my little 22 was covered in little blisters. I had the bottom peeled and dried out. Amazing how much water weight i was carrying around. My dry boat is much more lively.

[Mimsy]

The surveyor derives no financial benefit from offering his honesy opinion on how to best correct the issue. The broker(if its the sellers broker)however, DOES benefit if he can convince you that the cheaper repair method will be just fine.

Which opinion do you think is more trustworthy?

[minaret]

Peeling is definitely the superior method because it will allow the necessary amount of material to be removed while keeping the surface fair. The broker has no idea what he's talking about. Are the blisters restricted to below the waterline or are they above as well?

[Cheechako]

Peel, the un blistered gel coat will be soon! Hope there's enough glass on a cat for a peel!

[skipmac]

Another vote to peel. I just did my boat and researched and read everything I could on the subject before deciding. For multiple reasons I think peeling is the better option.

[teneicm]

Thanks guys. The more I read the more I agree with the peel. Someone offline also mentioned that sandblasting really roughens up the underlying fiberglass surface and makes it much more conducive to further water penetration due to the increased surface area. About the only benefit of sanblasting seems to be it's about 1/2 the cost.

[Ex-Calif]

I vote run away...

Unless the repair is completely and suitable factored into the price and you get it done professionally.

Dry out time can be significant and in that time you are not enjoying your new boat.

2 cents worth.

[bstreep]

Normally, I'm a "grind, fill, paint, forget" until the next bottom job kind of guy. But 50% coverage is a big deal. If you get a good deal, I'd certainly consider doing this, rather than running.

[skipmac]

Another comment. You mention the blisters are small but more important than diameter is depth and how far they spread under the gel coat.

Have you popped any? How deep does it go? Just under the gel coat or into the glass? Are they filled with brown, smelly liquid or clear slightly sweetish liquid?

Agree completely that the boat would have to be a really good deal. Get at least 2-3 estimates on the total cost of the repair, including hauling and storage while it is sitting for several months to dry, add 50-100% to that estimate and subtract that what a similar boat would sell for with a good bottom.

I just did a 42' monohull and just the peel and seal was $6000 and I think I got a very good deal. Figure double that for a cat plus a few boat bucks more for storage, etc and you could be looking at $20,000, in New England probably a lot more.

If you want to move the boat to N Florida I highly recommend the guy that did mine and would be a lot cheaper than New England.