How do I know if they're blisters?

[Don C L]

Even if they are blisters which looks debatable, they won't sink the boat. Make a slurry of baking soda, pop open a blister and slop it on. If there are bubbles, then it's likely a blister and you are now neutralizing the acid in it.

[Disailor]

When seawater molecules get thru the gelcoat & the water dries out it leaves the salt behind so sand to expose, flush with fresh water, wipe down with rubbing alcohol soaked rag, roll on barrier, paint.

[Disailor]

Results of Coast Guard authorized study as to cause & fix of blisters.

http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

[cyrano138]

Originally Posted by Disailor

When seawater molecules get thru the gelcoat & the water dries out it leaves the salt behind so sand to expose, flush with fresh water, wipe down with rubbing alcohol soaked rag, roll on barrier, paint.

Sand through all the gel coat? Or just see they're seem to be blisters?

[Disailor]

cyrano138:
See rbrazil's link (http://www.yachtsurvey.com/BuyingBlisterBoat.htm)
& the Coast Guard's study in my post.

The danger with blisters is that when saturated with water & subjected to freezing temps the expanding bubble can begin a process of expanding the void that started the whole business. Gradually(water soaks in freezes, expands allowing more water to seep in, etc) if left untreated some serious delamination can occurr.
If your winters are quite mild paint over & go sailing.

If you get some good hard freezing temps, I would just dremel the ones that have expanded such that when sanded substrate shows thru. Delaminated or fractured laminate is white sold laminate is transluscent. Dremel/grind all the white stuff away. Hose with plenty of fresh water to flush out the salt & whatever residue might have been exposed in the larger ones. When dry, wash with a clean rag & plenty of rubbing alcohol. This will evaporate any water that may have wicked into the fibers. Fair, then coat with Interlux 2000 (epoxy is not waterproof enough). Follow instructions regarding your brand of bottom paint & the barrier coat. Gelcoat didn't stop the water in the first place so I don't see the need to re-apply gelcoat.

I attempted to upload a photo of my blisterted bottom. There wasn't a square foot of bottom that didn't have a dozen blisters. In some places I had to remove so much white laminate that I had to leave plateaus so I'd have a reference plane when it came time to fair. Most all had some kind of liquid including that brown stuff. Took me 3 months but it's been 10 years now & no blisters.

[LittleWing77]

Originally Posted by Disailor

I attempted to upload a photo of my blisterted bottom. There wasn't a square foot of bottom that didn't have a dozen blisters. In some places I had to remove so much white laminate that I had to leave plateaus so I'd have a reference plane when it came time to fair. Most all had some kind of liquid including that brown stuff. Took me 3 months but it's been 10 years now & no blisters.

What an accomplishment!
(And must have given you some peace of mind over the years, eh?)

Nothing like a big job well done.
Warmly,
LittleWing77

[cyrano138]

Originally Posted by Disailor

Attachment 227552cyrano138:
See rbrazil's link (http://www.yachtsurvey.com/BuyingBlisterBoat.htm)
& the Coast Guard's study in my post.

The danger with blisters is that when saturated with water & subjected to freezing temps the expanding bubble can begin a process of expanding the void that started the whole business. Gradually(water soaks in freezes, expands allowing more water to seep in, etc) if left untreated some serious delamination can occurr.
If your winters are quite mild paint over & go sailing.

If you get some good hard freezing temps, I would just dremel the ones that have expanded such that when sanded substrate shows thru. Delaminated or fractured laminate is white sold laminate is transluscent. Dremel/grind all the white stuff away. Hose with plenty of fresh water to flush out the salt & whatever residue might have been exposed in the larger ones. When dry, wash with a clean rag & plenty of rubbing alcohol. This will evaporate any water that may have wicked into the fibers. Fair, then coat with Interlux 2000 (epoxy is not waterproof enough). Follow instructions regarding your brand of bottom paint & the barrier coat. Gelcoat didn't stop the water in the first place so I don't see the need to re-apply gelcoat.

I attempted to upload a photo of my blisterted bottom. There wasn't a square foot of bottom that didn't have a dozen blisters. In some places I had to remove so much white laminate that I had to leave plateaus so I'd have a reference plane when it came time to fair. Most all had some kind of liquid including that brown stuff. Took me 3 months but it's been 10 years now & no blisters.

Good lord. Well, mine aren't so bad or numerous, but who knows how it'll go. I'm heading back to it tomorrow and I'm going to open a few of them up. Most are small if they are blisters at all, and they don't give any result with a rapping test. The ones I'm concerned about are about the size of a quarter, but until I open them I'll have no idea how deep they are.

[cyrano138]

Well, I got into some of them today. A lot of them seem to be just through the gel coat or a tiny bit into the laminate. Those I'm going to fill with epoxy mixed with milled fiber. (1st photo)

There are a lot of areas where the chopped strand right under the gelcoat doesn't seem to have been saturated so well. I guess. That or the laminate is just literally one giant blister (or a million little ones). (2nd photo)

There are some larger ones, maybe about the size of a quarter, that go through the first layer, at least a few mm into the hull. Those I'm going to repair like any other repair, with a bevel and cloth patches. (3rd and 4th photos)

[cyrano138]

Any thoughts? How everyone had a great holiday weekend, by the way.

[Don C L]

Compared to some blisters I have seen, those look pretty superficial. A friend's boat had some deep ones and the smelly brown acid that forms in the blister helps also catalyze the reaction from what I have read. Did you have the acid coming out of those?

[cyrano138]

Now they were all completely dry, but the boat's been out of the water for at least the 3 years that I've had it, so it could have been plenty of time for them to dry out and unreverse osmose.

[Don C L]

Hmmm, that I don't know for sure but I suspect that liquid in the blisters is not likely to evaporate out of the blisters or drain out without leaving some kind of residue.

[rossdv8]

My last two 26 footers had blisters when I hauled out prior to purchase and had the boats inspected for insurance survey. The surveyor told me the blistering was pretty normal for yachts that had been moored for over 30 years.


He punctured a couple of the blisters and had me smell the inside and some fluid. From memory it was sort of vinegary, and he said that was a dead give-away that it was osmosis, but that a little osmosis would not sink either boat.


The repair on each yacht was relatively simple and not as expensive as I'd imagined. I sailed / lived in each of the yachts for about 5 years until they were wrecked in cyclones.



The first was a Doug Peterson / Tom Stephenson design and had been a well known racing quarter tonner and the factory's poster yacht at sales days. She was severly damaged in a cyclone in 2010, then completely rebuilt better than new and I inspected the hull during the process. As the surveyor suggested the osmosis had done no serious damage, only affecting the outer part of the layup. It was relatively easy to dry out and reimpregnate and barrier coat, then she was eventually returned to the water, sold, and is still sailing (now ( 10 years after the cyclone and 8 years after the rebuild (and more than 40 years old).


The second was also a quarter tonner designed by Doug Peterson and Bob Salthouse and was a much lighter construction. Where the first had openings made through the hull by big sharp rocks she was pounded on, the second yacht in a 2017 cyclone was washed onto a beach a little further around the anchorage onto a beach with flatter and rounded boulders. But she was opened up as if by a can opener.


However, like the first boat, the damage was not where the blisters / light osmosis had been. She opened up all around the toe rail area from the fore deck back to the start of the cockpit. By opened up, I mean I could reach in and take out bedding, galley stuff and nav gear!


Sorry for the long post. I get emotional about these last couple of my many small sailing boats.


Anyway, those bubbles look like mine did. The vinegary smell would be a dead give away should you puncture some of these blisters.


But when I first got the boats my shippy sanded them back, washed them out with something wet - probably acetone - and dried them for a week or so. Then he filled them with something he made up himself, sanded them, barrier coated them and painted with 2-pack.


And when I saw them after the cyclones, the parts where the blisters had been seemed fine..

[cyrano138]

I appreciate the long post. I think the boat should be fine if I repair them as I described above (small bevel and patch on the bigger ones and putty the smaller ones, then interlux, and paint). But when I say "fine" I mean "fine for my purposes."

I want to take this boat offshore, and possibly live on it, (which I realize a lot of people will balk at) so I need it to be good and strong. I expect a lot of responses to that may be that I ought to get a boat more suited to living aboard or cruising, but I don't have any money, and this is the boat I have and hence am stuck with, so I've got to figure out a way to make it work for what I want to do.

If not for all that, I'd slap some paint on and go. But I want it to be as strong as it can be, so I'm going to put some work into it. If I had all the time and money in the world I'd strip a few millimeters off the hull and rebuild it since, like I said above, it seems like the outer layer of mat didn't get saturated too well (you can see it in the picture). But then if I had all the time and money in the world I'd have a nicer boat like a cape dory 25 or a pearson triton anyway. The point is, I'm trying to compromise: the boat doesn't need to last for a hundred years or survive a hundred year storm, but it should be able to cruise offshore in weather and last more than a season.

I really appreciate all the people who've encouraged me here about fixing it and making it strong again. It's great to get the perspective of experienced sailors because around here, everyone seems to think saltwater only floats $400000 yellowfins with quad 500s on the transom.

Anyway please keep letting me know what you guys think!

[rossdv8]

In each case with my quarter tonners it took a cyclone that wrecked almost all other yachts in the vicinity to put them out of action.


As I recall from checking some of the work, the initial repairs when I bought the yachts were, as mentioned, mostly sanding / grinding / beveling around the blisters and washing them out, then drying them well, before filling what had been blisters.


There might be people on here that can describe the repairs more accurately.

After the repairs, I sailed each of the yachts locally and on coastal passages in tropical waters, often in 30 knots ans 2-3 metre seas. Any more than that I would try to hole up somewhere, but where I live 20 - 30 knots was considered a nice day (or night) for sailing, and the strong wind against tide means seas over a metre are quite suitable for a 16 foot off the beach catamaran. More than 2 metres just beans we move up to something around 25 foot and have to learn to slide diagonally across waves D)..