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Old 12-01-2016, 14:28   #1
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Osmosis \ blisters - acute?

Hello everyone, hope I put this question in the right place.

So I hauled my boat two days ago in the caribbean to put some new antifouling on it... And we saw that the hull is covered in blisters. The rudder especially, with big soft blisters. And when we pop them the brown acidy-smelling liquid comes out - osmosis. The boat is fiberglass, and it goes down between the layers of fiberglass.
I know that this did not happen in the few months that I've owned the boat, this takes a couple of years to build and the boat is almost thirty years old.
The problem is, we are on a quite tight schedule (picking up people + panama) and getting prices and estimated time-aspects around here seems impossible! In two days here we have no answers to when or how much. So...
... We were thinking about staying in New Zealand for half a year Starting in october (or when we get there). Would it be disasterous to sand the rudder now, put on a primer and antifoul and do the proper work in NZ? Then we'd go sandblasting, filling, the whole lot.
Could we? I know it's like putting a bandaid on a broken leg but our time and budget is very limited. We're talking ten months from now, hos much worse could it get?

Very thankful for answers!

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Old 12-01-2016, 14:34   #2
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Re: Osmosis \ blisters - acute?

How deep are they?
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Old 12-01-2016, 14:47   #3
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Re: Osmosis \ blisters - acute?

Maybe 1,5-2mm, just under the last layer of fiberglass.

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Old 12-01-2016, 14:50   #4
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Re: Osmosis \ blisters - acute?

Quote:
Originally Posted by cybber View Post
I know that this did not happen in the few months that I've owned the boat
//
The problem is, we are on a quite tight schedule (picking up people + panama) and getting prices and estimated time-aspects around here seems impossible!
Without pics or a vid to see how bad it is I feel I need a disclaimer, but ...
... I'd sail the boat to NZ and take care of it there.

I'm not sure how you missed this when you bought the boat, or why didn't deal with it then?

You're planning a serious trip, and "oh darn, forgot about the osmosis" shouldn't really happen - nor should "oh darn, maybe we should have checked the boat before buying it" ...

Which is why I want a disclaimer: if you never checked below the waterline, it could be a very severe case of osmosis that everybody has ignored for years for some reason (and if they did: what else did they 'forget' to check / fix / maintain?). But still: very few boats actually go down due to osmosis.

This is what we did when we (intentionally ) bought a boat with osmosis: opened all the blisters, washed them out, let them dry out, then used 2 kinds of epoxy - inject and glue in Dutch - a thin one and a thick one. Sorry, don't know the correct terms for these products in English. Not a fun job by any means, but not that big of a deal either.
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Old 12-01-2016, 15:44   #5
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Re: Osmosis \ blisters - acute?

Schedule vs. preparedness...lot of ocean between Panama and New Zealand. There is lots to consider with blisters, like moisture content of the hull...too much and repairs won't adhere. Much to learn. May be best to do nothing rather than bandaid...Probably won't sink...I wonder what else is wrong with the vessel that you have only owned for a few months. I vote for a complete survey...
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Old 13-01-2016, 09:21   #6
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Re: Osmosis \ blisters - acute?

Delamination usually takes places several years after the first blisters. I think it is pretty safe to sail for at least another year or so. And New Zealand or Australia is much better place than anywhere in Caribbean for osmosos treatment.
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Old 13-01-2016, 09:29   #7
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Re: Osmosis \ blisters - acute?

Two things
I've never heard of Osmosis sinking a boat, but it is like rust, it doesn't get better over time.
From my understanding, a fix takes months on the hard as you have to let the hull dry thoroughly, even if you have advanced means of drying, it's not a quick job.
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Old 13-01-2016, 10:03   #8
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Re: Osmosis \ blisters - acute?

The advanced means of drying is not to let it sit, or to heat it, or whatever - or at least, that's the case if it's a polyester layup.

Blisters and delamination in that case are caused by incomplete catalyzation which leaves water soluble material(s) - WSM.

When water reaches it/them, it expands, thus a blister.

The way to 'dry' such a boat is to open each one by grinding back to where there's no evident delamination, and then thoroughly wet (water - soluble, remember) down the boat. Identify remaining (stains, weeps) places, grind back, and then pressure wash.

Repeat until there are no more apparent issues. Then do it again to make sure. Then get a steam pressure wash, which might reveal one or two tiny remainders. Resolve those.

Repair all the gouges with fiberglass. Fair with something like AdTech or other epoxy fairing compound. Barrier coat and bottom paint.

You can see exactly that process here:

Pictures: Flying Pig Refit 2011-2012/Bottom Job
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Old 13-01-2016, 10:10   #9
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Re: Osmosis \ blisters - acute?

The part with the steam pressure wash forward starts here:

Pictures: Flying Pig Refit 2011-2012/Bottom Job/2- Repair and Fair
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Old 13-01-2016, 10:31   #10
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Re: Osmosis \ blisters - acute?

Here is our experience. Back in the 1980s a 47 foot cheoy lee luders had a huge blister on its starboard side from the turn of the bilge to the waterline. 6 feet long, and about 5 feet wide. Hull had the boat pox that evidently lead to total delamination of the fiberglass hull in that area. Lead to the blistered area being cut out and rebuilt. The owner did not notice the problem until trying to sail the boat back to the mainland. Strange "whoomping" sounds suggested something was wrong. When the boat was hauled, the hull was still watertight but at some point the glass would have broken with the repeated flexing.

So its not just the pox you need to worry about, but whether it has lead to delamination of the core roving. If the pox is just in the gelcoat, not a big issue. If deeper, then you really do have problems. Beware of boats with marinetex or similar repairs to blisters. Unless the hull is resealed with a vinyl coat, it will allow water to migrate around the patch and eventually pop it out. So bottom line, get a good life insurance policy.
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Old 13-01-2016, 11:07   #11
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Re: Osmosis \ blisters - acute?

Quote:
Originally Posted by cybber View Post
Hello everyone, hope I put this question in the right place.

So I hauled my boat two days ago in the caribbean to put some new antifouling on it... And we saw that the hull is covered in blisters. The rudder especially, with big soft blisters. And when we pop them the brown acidy-smelling liquid comes out - osmosis. The boat is fiberglass, and it goes down between the layers of fiberglass.
I know that this did not happen in the few months that I've owned the boat, this takes a couple of years to build and the boat is almost thirty years old.
The problem is, we are on a quite tight schedule (picking up people + panama) and getting prices and estimated time-aspects around here seems impossible! In two days here we have no answers to when or how much. So...
... We were thinking about staying in New Zealand for half a year Starting in october (or when we get there). Would it be disasterous to sand the rudder now, put on a primer and antifoul and do the proper work in NZ? Then we'd go sandblasting, filling, the whole lot.
Could we? I know it's like putting a bandaid on a broken leg but our time and budget is very limited. We're talking ten months from now, hos much worse could it get?

Very thankful for answers!

Sent from my YOGA Tablet 2-1050F using Cruisers Sailing Forum mobile app
You will get many opinions on this problem, but your first paragraph describes a serious problem. When a hull is "covered in blisters" it is rarely, if ever, proper to repair each individual blister. It is indicative of a much larger problem...
There are issues such as secondary bonding when making spot repairs, and the virtual impossibility of getting the substrate dry enough.
You really need to have the moisture content of the hull checked electronically by a competent repair facility to properly assess the extent of the problem.
In many, if not most, cases of severe blistering the hull needs to be peeled down to unaffected fiberglass, dried properly [which as stated earlier, can take months], and have as many layers as necessary of fiberglass built up until proper thickness is reached.
Even then, you have a hull with a potential for secondary bonding problems unless the resin used is perfectly compatible with the original, and the layers of glass are properly laid up.
I'm not sure anyone can reasonably tell you the boat is seaworthy without having a competent fiberglass repair facility investigate the extent of damage.
Repair of osmotic blistering of fiberglass hulls is a thriving business...there is a reason for that.
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Old 13-01-2016, 11:12   #12
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Re: Osmosis \ blisters - acute?

Endorsed. That's the way to do it.

Ray

Quote:
Originally Posted by skipgundlach View Post
The advanced means of drying is not to let it sit, or to heat it, or whatever - or at least, that's the case if it's a polyester layup.

Blisters and delamination in that case are caused by incomplete catalyzation which leaves water soluble material(s) - WSM.

When water reaches it/them, it expands, thus a blister.

The way to 'dry' such a boat is to open each one by grinding back to where there's no evident delamination, and then thoroughly wet (water - soluble, remember) down the boat. Identify remaining (stains, weeps) places, grind back, and then pressure wash.

Repeat until there are no more apparent issues. Then do it again to make sure. Then get a steam pressure wash, which might reveal one or two tiny remainders. Resolve those.

Repair all the gouges with fiberglass. Fair with something like AdTech or other epoxy fairing compound. Barrier coat and bottom paint.

You can see exactly that process here:

Pictures: Flying Pig Refit 2011-2012/Bottom Job
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Old 13-01-2016, 11:41   #13
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Re: Osmosis \ blisters - acute?

Quote:
Originally Posted by morven55 View Post
Repair of osmotic blistering of fiberglass hulls is a thriving business...there is a reason for that.
Two reasons, even

1 - repair the serious cases (as this may well be, tho no way to tell w/out some pics)
2 - people panicking and fearing osmosis so 1 small blister and they are willing to pay thousands of $.

Not to say osmosis can't be a serious issue - it sure can be, but it can also be a case of a few blisters and you can fix it yourself.

I am more worried about the OP saying he purchased this boat a few months ago and only now discovered the blisters. From the info as posted, it sounds like a poorly maintained boat bought w/out a decent survey or even a haul out. I would not take a boat like that on a trip as the OP has planned ...
(Please note I said 'sounds like' - I could be plain wrong here!).
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Old 13-01-2016, 11:46   #14
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Re: Osmosis \ blisters - acute?

We crossed the Pacific, Panama to New Zealand, last season and we have just got out of a very good boat yard, Bay of Islands Marina, in Opua NZ. It has excellent boat builders and with the weak NZ$ skilled workers are about $50/hr.

However, crossing the Pacific is 7,000+nm and 60 to 70 days at sea and of the 200 boats we know that crossed, last season, there was a high failure rate. One sank from structural problems, one lost the rig, there were 2 rudder failures and several others had serious rig and engine problems.

Latitude 38 - 'Lectronic Latitude

I personally would get the boat fixed properly and delay the Pacific.

70 days at sea crossing the Pacific is more stress than many coastal cruiser boats experience in a life-time of sailing the bay! The boat that sank was 1,500 miles off-shore and had been subjected to days of 'bashing.' Repair facilities are non-existent until you reach Tahiti which is 4,500nm from Panama!

Good luck but remember that you should never be in a hurry to get into trouble at sea!
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Old 13-01-2016, 11:58   #15
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Re: Osmosis \ blisters - acute?

Quote:
Originally Posted by Lizzy Belle View Post
Two reasons, even

1 - repair the serious cases (as this may well be, tho no way to tell w/out some pics)
2 - people panicking and fearing osmosis so 1 small blister and they are willing to pay thousands of $. Not to mention the costly prevention measures on boats that showed no sign of osmosis.

Not to say osmosis can't be a serious issue - it sure can be, but it can also be a case of a few blisters and you can fix it yourself.

I am more worried about the OP saying he purchased this boat a few months ago and only now discovered the blisters. From the info as posted, it sounds like a poorly maintained boat bought w/out a decent survey or even a haul out. I would not take a boat like that on a trip as the OP has planned ...
(Please note I said 'sounds like' - I could be plain wrong here!).
Your logic is always sound, and you give good advice, as usual; at least in my humble opinion! :]

Having said that, the description given in the OP's first paragraph is the sort of problem that, at the very least, requires some in depth investigation.

I worked in boatyards for 17 years, and have seen it all, believe me. Osmotic blistering can be minor and easily repairable if caught early and properly repaired, including a barrier coat after serious sanding of hull. I have seen MANY hulls "covered in blisters" that were only repairable by peeling the entire hull until [relatively] dry materiel was reached...then many layers of mat/roving/cloth.

I'm not one for gloom and doom and all the negative gossip found in boat world, but some things need to be in proper order, and the hull of an ocean-going vessel is at the top of my list.

I do agree that the mention of "osmosis" causes fiberglass boat people to go into panic mode, and it is not always necessary, but there are many cases that require serious repair work and the cost can be more than the value of the vessel.

Fiberglass is an excellent boatbuilding materiel, but proper maintenance is requires, as it is with wood, steel, and ferro.
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