A1Sailor
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Antifouling isn't imperveous to water - the hull can dry out through it. If it were imperveous, there would be no need for "Gelshield" type epoxy coatings.
Leave in/take ashore - for winter???
- Thread starter Robert Wilson
- Start date
garvellachs
Well-Known Member
Tony Staton-Bevan in Osmosis & Glass Fibre Yacht Construction (1995) says: "If at all possible, the vessel should be stored ashore when not in use. The benefits are two-fold, the hull will not be absorbing water during this period and it may even partially dry out. It is no coincidence that those craft left afloat for 12 months every year, develop blisters much earlier." (p108)
Many of us who sail and look after elderly yachts built before the change to better resins may do well do heed his advice?
garvellachs
Well-Known Member
We bought a mid-80s Maxi 100 with osmosis and had her treated in the Lake District. The hull was peeled in the Autumn and was left to dry over the winter outside. The hull was washed down weekly I think during that time. The measured moisture levels dropped steadily until in the Spring she was ready to be filled faired and epoxied. To dry her didn't look difficult at all to me, just took time.
jwilson
Well-Known Member
Not no hope: they'll just get high moisture levels and possibly blisters earlier than they would if they had been ashore each winter. And if and when they do, they won't sink. Just be more difficult to sell.
Newer hulls with isopthalic or vinylester gelcoats resist water absorption better, but are probably not totally immune to it. Bear in mind that many buiders only use the expensive isopthalics or vinylesters as gelcoats only - the main body of GRP laminate is often the cheaper orthopthalic resins.
I have heard a surveyor say that he is seeing occasional cases of blisters in newer boats, as buyers believe their new improved gelcoats make the hull OK for constant immersion.
I met osmosis blisters first in Hong Kong, where most cruising and cruiser/racer boats spend 364 and a half days a year afloat in warm water. The yacht I bought had lots of blisters on a 1960s heavy layup GRP hull, blisters very quickly ground out and filled. Had to be quick - shore boatyard space was very scarce and expensive. 15 years later there were some more blisters.
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garvellachs
Well-Known Member
OK, accepted.
D
Deleted member 36384
Guest
You can research on line why this advise is both old school thinking and possibly wrong, especially on older GRP formulations and construction methods. Water molecules that move through GRP do so because they are small enough to move through (the hull does not absorb water). As they pass through the GRP they can come in contact with other chemicals and may react such that the new compounds have bigger molecules that will not travel through the composite. The only way to get the bigger molecules out is to peal the GRP off and use natural ventilation or more efficiently use a Hot Vac system.
It has been established that you can take a new boat, measure the moisture reading before she has ever seen water, launch her and at the end of the season, maybe even less time than that, when you take her out the water, immediately perform a moisture survey and it is very likely that she will show elevated moisture readings. A week or so later, if repeated, more or less independently of the atmospheric conditions, the moisture levels will have reduced back to the new state, or very close.
On older boats that have old resin formulations and old manufacturing methods the GRP can have dry glass fibres (wicking), air bubbles, uncured resin, bonded in materials for GRP stringers (foam, wood, rope), fairing foam covered in GRP at skegs, encapsulated keels, shaft tunnels, bonded in ply. All these materials or defects can trap moisture such that it will not easily be removed again.
There is also an opinion that the cooling effect of water, or even molecules of water moving through the GRP, slows down the reaction that is happening to cause osmosis - refer to this book http://www.osmosisinfo.com/osmosis book.html and as such the boat should be left in the water. The logic with this statement is that the transfer of water molecules happens from day 1 and if a reaction is going to happen it starts in day 1.
As a buyer of an old boat and now owner, I looked into this in quite some depth. There is even a belief from chemists that all our GRP boats, even todays GRP boats, will simply break apart over some long period of time as the resins are not stable compounds and will inevitably break down (they just appear stable in our time frames).
Drying out is not a reason to lift out every year, the water molecules have already started the damage and lifting out will not stop it from happening, which is the conclusion I have come to. There are other reasons of course to lift out annually, especially on older boats that require a lot of TLC to maintain.
It's never straight forward advice, we all can find sources to back up our experiences or shore up our knowledge. The books that talk about the chemistry and physics involved in osmosis I tend to believe. Maybe I am wrong.
Robert Wilson
Well-Known Member
Several illuminating reports. Thank you.
Rightly or wrongly, this morning I agreed with the Ullapool boatyard to take Khamsin out of the water in the next four/six weeks. She'll stay ashore, hull un-covered, until springtime.
The local boatyard chap won't be ready until next season - and when I told him my mooring just along the shore from his slipway had not been serviced since new in 2010 he agreed I was doing the right thing by not risking leaving her in the water.
Sorted :encouragement:
But keep the Post and dialogue going, I'm fascinated and may even be learning something
Rightly or wrongly, this morning I agreed with the Ullapool boatyard to take Khamsin out of the water in the next four/six weeks. She'll stay ashore, hull un-covered, until springtime.
The local boatyard chap won't be ready until next season - and when I told him my mooring just along the shore from his slipway had not been serviced since new in 2010 he agreed I was doing the right thing by not risking leaving her in the water.
Sorted :encouragement:
But keep the Post and dialogue going, I'm fascinated and may even be learning something
[70521]
Well-Known Member
I am not at all confident about a document that was written quarter of a century ago. We have a lot more experience of the material and to this day we don't see any boats sinking due to "soggy hulls".
Prior to buying my current boat, launched 1986, it had been ashore for 15 months and the moisture readings were "in the usual range for a boat of that age", to paraphrase the surveyor. Now Devon is not the driest county but clearly the 15 months ashore, in this case, made no significant change.
At my age I am pretty sure the boat will outlast me, just hope there is some way that I can dispose of her in an environmental way.
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doug748
Well-Known Member
This is lately revised and worth inspection:
https://r.search.yahoo.com/_ylt=Awr...s3v6.pdf/RK=2/RS=z.YPuXpriX59x_HXL3qtYN.i2ng-
https://r.search.yahoo.com/_ylt=Awr...s3v6.pdf/RK=2/RS=z.YPuXpriX59x_HXL3qtYN.i2ng-
A1Sailor
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Several illuminating reports. Thank you.
Rightly or wrongly, this morning I agreed with the Ullapool boatyard to take Khamsin out of the water in the next four/six weeks. She'll stay ashore, hull un-covered, until springtime.
The local boatyard chap won't be ready until next season - and when I told him my mooring just along the shore from his slipway had not been serviced since new in 2010 he agreed I was doing the right thing by not risking leaving her in the water.
Sorted :encouragement:
But keep the Post and dialogue going, I'm fascinated and may even be learning something
Well she's still in the water. Might you change you mind and do some winter sailing?
Perhaps you could buy some snow shoes and walk out to her on her mooring.
Robert Wilson
Well-Known Member
Well she's still in the water. Might you change you mind and do some winter sailing?
Perhaps you could buy some snow shoes and walk out to her on her mooring.
With those reports I am rather pleased with myself - providing I get her out before November's Climate Catastrophe arrives!
Or is that a classic FAKE NEWS
Oddly, when I lived down in Northeast England there was nearly always snow on 11th. November.
Not so up here - YET
garvellachs
Well-Known Member
Tony Staton-Bevan's advice is based on surveying 100s of boats at that time. GRP boats had been around since the 70s or earlier. The process of so-called "osmosis" may be better understood today but his observations were/are just that, observations. At that time boats kept afloat developed blisters earlier. Reading Clegg's (rev 2107) booklet seems to support the idea that time out of the water delays the onset of blisters: "In practice, many yachts are sailed for with ‘high’ moisture readings for ten years or more without their owners being aware of any problems; so the perhaps best advice at this stage would be to leave well alone, whilst keeping an eye on the problem, and delaying any further damage by wintering ashore if at all possible." (p5)
garvellachs
Well-Known Member
That's an interesting read, though not an easy one. Same for Clegg's booklet cited just after. I acknowledge the misnomer "osmosis". I didn't pick up the idea in Blomberg that keeping a boat in cold water might slow down the problem - where was that? Certainly he referred to the problem being exacerbated by keeping a boat in commission/use all winter because of the supply of moisture inside from condensation. And I think he mentioned that higher temperatures accelerate the onset if moisture is present. Clegg seems to be more dismissive of the idea that using heat to dry/cook the laminate improves or even solves the problem by curing the uncured problem resin. A consensus might be that boats develop the problem at varying speeds depending on their build materials and quality and that little can be done to stop it because moisture is omnipresent . Some will last a very long time.
Unfortunately Blomberg might be slightly less than independent, having a business interest in the process of fixing the problem.
Maybe I am wrong too, but our boat has been wintered ashore since her launch (mostly in the Baltic) and I think I'll stick to it now; anyway these days our insurer wants her out from November to March because she's kept on a swinging mooring.
maby
Well-Known Member
I don't think there is any rocket-science involved in this decision - GRP does absorb some water when immersed. I'm not convinced that a boat left out of the water over the winter will actively dry out, but surely that is not necessary for boats that are taken out to have less water in their hulls than the equivalent boat left in all the time - the absorption is a slow process and the boat that is only in the water six months per year is going to absorb less than one which is in the water all the time.
How much this actually matters probably depends on how old you are. As others have said, there are vanishingly few examples of boats actually becoming unusable due to osmosis. Even the older generation boats seemed to last 20 years with no great difficulty and the received wisdom is that a boat launched today will have a significantly longer service life than that. My recently purchased boat is going to outlive me - at least from the osmosis point of view. When I die, it will become part of my estate and go to my son - who has no interest in sailing. If it is 20 or thirty years old, its resale value will be pretty low. Am I going to treat it with kid gloves so that the hull will be a bit drier when my son comes to dispose of it? Certainly not - I enjoy winter sailing and it will stay in the year round minus a few days for antifouling.
An owner who is a fair bit younger than me may take a different view - if I were thirty and had just purchased a brand new boat that I anticipated sailing for the next fifty years, then I might pay more attention to keeping the hull as dry as possible.
How much this actually matters probably depends on how old you are. As others have said, there are vanishingly few examples of boats actually becoming unusable due to osmosis. Even the older generation boats seemed to last 20 years with no great difficulty and the received wisdom is that a boat launched today will have a significantly longer service life than that. My recently purchased boat is going to outlive me - at least from the osmosis point of view. When I die, it will become part of my estate and go to my son - who has no interest in sailing. If it is 20 or thirty years old, its resale value will be pretty low. Am I going to treat it with kid gloves so that the hull will be a bit drier when my son comes to dispose of it? Certainly not - I enjoy winter sailing and it will stay in the year round minus a few days for antifouling.
An owner who is a fair bit younger than me may take a different view - if I were thirty and had just purchased a brand new boat that I anticipated sailing for the next fifty years, then I might pay more attention to keeping the hull as dry as possible.
[70521]
Well-Known Member
Thanks for the link doug, an interesting read.
Not sure I agree with a lot of what he says and there appears to be very little science behind his conclusions, e.g. <i>In typical UK boatyard conditions, Propylene Glycol will absorb more than 65% of its own weight in atmospheric moisture if allowed to stand in an open glass beaker for a prolonged time</i>, now the engineer in me is questioning
a) what are typical UK boatyard conditions - typical for Cornwall, tropical maritime air or Kent, tropical continental or Scotland and the east coast, polar/arctic maritime air;
b) If I allow anything to stand in a glass beaker it is going to fill with water, was it covered; and
c) how long is a prolonged time a week, a month, a year or a decade.
I am sure he know his stuff, I still suggest we have many decades of experience and as yet nobody's hull has dissolved and looking at all of the wrecks lying/floating in the creaks and rivers around our coasts are very unlikely so to do.
Out of interest it would be fascinating to lift a boat that had been a float for years, I can think of two on the Exe, clean them off, empty them of water and take some moisture readings on the hull and see what results they had. It would also clear the river of two eyesores that will become a navigation problem when they finally sink.
langstonelayabout
Well-Known Member
The 'IMPENDING CATASTROPHE' light is flashing in the corner of my screen.
I had a boat break it's 3 year old chain mooring in a force 6 a few years ago. Some good chaps from the club rescued it within minutes so I only needed to replace rigging, not the boat.
Please, Please, Please check that mooring chain and sinker. I've seen pin-thin worn 10mm chain. 12mm thick wire hoops broken at the top of 2 tonne sinkers. Knackered swivels work through with sand carried by the tide in a couple of years. For the sake of your being able to sleep on a bad winter's night, make sure your mooring is good, even if you have to pay someone to lift it and carry out the maintenance yourself.
Robert Wilson
Well-Known Member
I one hundred per cent agree with you. A big part of my decision to have Khamsin ashore this winter is just what you say. Annoyingly there are very few mooring people up here and they all seem to have no time to check my mooring(s), even though I have told them I'll pay.
I hope to have found another moorings guy, but he's proving difficult to track down.
I hope my insurers don't monitor YBW posts...……………………………..
Thanks for your concern.
ctva
Well-Known Member
I one hundred per cent agree with you. A big part of my decision to have Khamsin ashore this winter is just what you say. Annoyingly there are very few mooring people up here and they all seem to have no time to check my mooring(s), even though I have told them I'll pay.
I hope to have found another moorings guy, but he's proving difficult to track down.
I hope my insurers don't monitor YBW posts...……………………………..
Thanks for your concern.
I missed this interesting thread the other day. Busy working...
In it all, the age of the uninspected mooring would be my concern too. When we used a mooring it was checked every 2 years. We'll be staying afloat again this winter, albeit in fresh water but will look to dryout somewhere next summer to change the anode. Glad you've got things sorted and will be good for your peace of mind.
Chris
Robert Wilson
Well-Known Member
Thanks Chris. Yes, the moorings will be checked before relaunch next year. Somehow!
Storm Callum ( only a juvenile at the mo) is making itself very much felt as I type. Khamsin is tugging hard on the warp(s) with the wind zooming across from the big beach (Gruinard). The rocks are about 150metres astern of her...……………
Sunny, hot, sociable days seem a long way away now, don't they!
Good luck with changing the sea's salt water to fresh
Storm Callum ( only a juvenile at the mo) is making itself very much felt as I type. Khamsin is tugging hard on the warp(s) with the wind zooming across from the big beach (Gruinard). The rocks are about 150metres astern of her...……………
Sunny, hot, sociable days seem a long way away now, don't they!
Good luck with changing the sea's salt water to fresh
Kelpie
Well-Known Member
Robert
out of curiosity, how is your mooring made up? In particular the size of the ground and riser chains.
out of curiosity, how is your mooring made up? In particular the size of the ground and riser chains.
