Viewing a boat with Osmosis

dolabriform

dolabriform

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Hi All

I'm viewing a boat tomorrow that has a high level of Osmosis and I'm wondering wether to go ahead or walk away.

We can't afford to get it done now, and so we're really unsure about what to do.

I've heard the phrase "a boat never sunk from Osmosis", but I'm wondering how bad it needs to get before it becomes uneconomical to repair. The boat is 37ft.

Any thoughts appreciated

Thanks
 
I guess it depends what is meant by high level of osmosis. I would have a look at it and see how many and how big/deep the blisters are and whether you think this is too much. It depends how much work you want to do.

My boat had quite a lot of blisters when I bought her which did not put me off, she dates from 1980 after all. Many were quite small dry ones and a few were bigger and wet. I had her soda blasted which opened them out and got rid of all the old a/f. I then washed them out and left her on the hard over winter. In the spring I sanded and filled them all with epoxy filler, put on 4 layers of gelshield and have not had any appear or any problems in the last 5 years. I was worried about putting gelshield over what was still a bit of a 'wet' hull but it has not been a problem.
 
Depends on what type/size/value of boat, and on how long you expect to keep it for.

If I were buying a boat to keep long-term, it wouldn't bother me as long as the price reflected it. If however I though that I might only keep it for a couple of years, I wouldn't touch it because you will have trouble selling it on.
 
Bobc said:
Depends on what type/size/value of boat, and on how long you expect to keep it for.

If I were buying a boat to keep long-term, it wouldn't bother me as long as the price reflected it. If however I though that I might only keep it for a couple of years, I wouldn't touch it because you will have trouble selling it on.
Click to expand...

Thanks Bob. We are planning to keep this for a long time, and have a quote of 8k to fix it.

I know that I'm asking about a piece of string here, but does it become a big problem at any stage, ie does it do irreparable damage?
 
neilf39 said:
My boat had quite a lot of blisters when I bought her which did not put me off, she dates from 1980 after all. Many were quite small dry ones and a few were bigger and wet. I had her soda blasted which opened them out and got rid of all the old a/f. I then washed them out and left her on the hard over winter. In the spring I sanded and filled them all with epoxy filler, put on 4 layers of gelshield and have not had any appear or any problems in the last 5 years. I was worried about putting gelshield over what was still a bit of a 'wet' hull but it has not been a problem.
Click to expand...
The small dry bubbles were probably due to poor brushing out of the gel coat in the mould to remove any air. It is a common problem from boats of this era. The dry bubbles should only be 2 to 3mm in diameter, whereas osmosis blisters are considerably larger and when burst have a vinegar smell. Hope this helps the OP to understand what he is looking at on the hull.
 
I am also keen to learn what is so bad about osmosis?
I know its a great price negotiation point - a way to get a lower purchase price when buying, but what's really the problem with osmosis? (not how is it fixed, what fixing it costs, who is good or bad at fixing it).
 
dolabriform said:
Thanks Bob. We are planning to keep this for a long time, and have a quote of 8k to fix it.

I know that I'm asking about a piece of string here, but does it become a big problem at any stage, ie does it do irreparable damage?
Click to expand...

The damage depends on how the moisture was absorbed. If it is purely a Gelcoat - Laminate interface matter - then blisters are unsightly and mainly cosmetic as Gelcoat is not structural. But if the moisture has penetrated deeper ie by wicking or poor layup of the laminate - then it can over time lead to limited damage structural integrity. But it takes a long time for this and would not normally result in structural loss.

Most people would if they really are serious about the particular boat - negotiate a price reduction based on the Survey findings.
 
dolabriform said:
Thanks Bob. We are planning to keep this for a long time, and have a quote of 8k to fix it.

I know that I'm asking about a piece of string here, but does it become a big problem at any stage, ie does it do irreparable damage?
Click to expand...

I would get £8k off the price and buy it then, and just live with the blisters. A lot of the time, you pay the £8k to get it peeled and sorted, and 5 years later the blisters start coming back anyway.

Generally speaking, it has little or no bearing on the structural integrity of the boat, it's just cosmetic which nobody sees except the fish.
 
dolabriform said:
Thanks Bob. We are planning to keep this for a long time, and have a quote of 8k to fix it.

I know that I'm asking about a piece of string here, but does it become a big problem at any stage, ie does it do irreparable damage?
Click to expand...


Go look, take pics (hold a tape against the blisters for scale) and come away to think. The 8k is, i presume, to remove the gelcoat and repair, then Gel Shield ? You might just be able to repair individual blisters yourself, or get the gelcoat removed and do the rest yourself, for a fraction of the cost. On the other hand, if the boat is £20k cheaper than the next one, spending £8k is still a good deal, the boat is cheap and it's epoxied. It would need to be otherwise in good order though.
 
dolabriform said:
Thanks Bob. We are planning to keep this for a long time, and have a quote of 8k to fix it.

I know that I'm asking about a piece of string here, but does it become a big problem at any stage, ie does it do irreparable damage?
Click to expand...

£8k was what Hayling Yacht Services quoted to fix mine. It was a full gel strip, heated pads and then re-gelling epoxying. As my boat is worth £17K there was no point. I can see by other comments you are going to get advice both ways as there are polarised views on osmosis. A boat with osmosis will be cheaper as they are more difficult to sell. It gives the opportunity to get a bigger/better boat in other ways than you otherwise could. It does mean though that it would be best to do some work on it to keep it in check. I don't think it is an onerous DIY job if you are practical as it is a case of doing proper prep and repair costing a few hundred. It won't be the same as a full treatment but will stop the problem getting worse. If you don't want the hassle, or are not practical, or it worries you, don't get a boat with it.
 
My experience is that 'cures' for boat pox are rarely permanent.
So if it's beyond what you can just live with, you need to be perhaps looking at allowing for the next buyer to beat you down by the price of more remedial work when you sell in 7 to 10 years time.

Boat pox is the resin breaking down due to the effects of water. Hydrolysis. Strong resin turning to smelly stuff of no structural value. It isn't making the boat stronger.
While it's folk knowledge that 'no boat sank from osmosis', that phrase was coined when boats were overbuilt. You wouldn't want the resin in a Bene 40.7 to lose many % of its strength.
 
The osmo man at Gweek told me some, a very few, light moulded hulls have been scrapped. Basically, as I understand, the width of a blister is a measure of its depth, roughly an equilateral triangle, so if your hull is thin it could weaken it, but only in spots, and how close together are they? I was told my FV hull was compromised by 20% and it didn't matter as it was so thick. I carried on for 26 years and sold it on survey, no effect on value. Pimples up to 18-20mm.
 
Boat pox is the resin breaking down due to the effects of water. Hydrolysis. Strong resin turning to smelly stuff of no structural value. It isn't making the boat stronger.
Click to expand...

?? Boat pox as you put it is mainly due to two factors :

Moisture entering through the gel coat and dissolving salts / any uncured resins in any tiny void it finds. This increases its density - it cannot then exit ... it leads to blisters as it expands. Osmosis
Moisture entering via cracks or other structural defects such as 'dry unresined' fibres commonly termed wicking - again it leads to a build of higher density fluid in any void it finds.

The Vinegar smell is from the catalyst used to cure the hull resin and any salts it dissolves.
 
This is a great opportunity to buy a boat at a very reduced price. Boats do not sink because of osmosis. Osmosis is like Japanese knotweed; it doesn't really matter. When you have time in a few years, get the boat out of the water, grind the blisters and fill them with epoxy. Is the boat a mass-production boat or homemade? any pictures of the extent of the blisters? I wouldn't pay £8k for the repairs; most likely, osmosis will come back anyway. Just repair it yourself. Make a low but sensible offer and go for it; Good luck
 
I think the only qualification to the various advice given above would be to ask if you intend to race the boat? Osmosis - and the correspondingly "wet" GRP - will add to the weight of the boat and may impact a bit on performance. Not enough to notice if you are just cruising between ports, but if you are planning on taking racing seriously, you may notice the difference.
 
maby said:
I think the only qualification to the various advice given above would be to ask if you intend to race the boat? Osmosis - and the correspondingly "wet" GRP - will add to the weight of the boat and may impact a bit on performance. Not enough to notice if you are just cruising between ports, but if you are planning on taking racing seriously, you may notice the difference.
Click to expand...

I doubt that very much.
IIRC 'saturated' GRP has a moisture content of 3 or 4%? So only a few kilos over the underwater area.
Unless your blisters add up to a lot of litres, in which case the shape of the thing will be slowing you down more than the weight.
 
Thanks for all the comments so far.
Presuming there is nothing else that's an issue I think we will make a sensible offer.
The boat was made in 1987, so I'm guessing she's pretty well laid up. A surveyor I spoke to today said they were tough boats.. so hopefully that bodes well.
I'll update once I've viewed her tomorrow.
 
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