Boat lift out to dry out?

Just about everything you ever wanted to know about osmosis is contained in a PDF that can be dowloaded from Nigel Clegg's Passion for Paint site here.

Very useful guide imho and deals with many of the osmosis myths that exist.
 
If not protected by epoxy it is 4 weeks less water absorption, but the water, when it passes into the hull, becomes heavier by dissolving parts of the hull lay up and doesn't really come back out again. So you get 4 weeks respite from getting wet but you don't get 4 weeks...

I suppose I'm now beginning to question if most surveyors really do recommend it these days. I will ask the ones I meet as I go along :)

Interesting. On that basis, the only difference between one boat permanently immersed and another lifted for four weeks is that the latter absorbs 48/52 of the water absorbed by the former. Or about 93%.

It would be interesting to know how many of the surveyors you meet continue to recommend this, as I may adjust my boat's time on the hard if they tell you it's a waste of time. Ta. ;)

AdeOlly - thanks for that link.
 
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Anyway....all points very interesting and informative.
(Except for the Scuttlebutt anchor remark)
No need dude, play nicely!!!

It seems the overall decision, is to let it dry for a few weeks!
Summertime, definately...not too sure about the colder seasons though!

At the end of the day, is there any other way of spotting excessive moisture damage, other than blisters???

I have built Sealine boats (up in Kidderminster) for 23 years, and have recently been repairing gelcoat & GRP for a living!

A boat i recently worked on had minor osmosis around the bow area!
There were approx" 20 blisters.
I ground each one back to dry glass....Filled with an epoxy filler, then re-antifouled.
Osmosis/Hydrolisis....

Just because you see an osmosis blister...doesnt mean the problem is everywhere below the water line!
There is a chemical called "Phthallic" acid already present in polyester resins, which when exposed to water (with different salinities) , creates those nasty osmosis blisters!!!!
Water displacement, through the weight of the boat
(which varies enormously) increases the pressure below the waterline ,accellerating these problems!
Another contributing factor is ,...once the moisture has penetrated the gelcoat membrane, the actual Glassfibre strands themselves, suck/pull/draw the moisture around by way of capillary!

So ..to cap it off...dont lose too much sleep over it all !!!
 
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Just about everything you ever wanted to know about osmosis is contained in a PDF that can be dowloaded from Nigel Clegg's Passion for Paint site here.

Very useful guide imho and deals with many of the osmosis myths that exist.

Good download.

Im not too concerned .Boat has just turned 10 years old so I assume the layup would be less susceptable to problems than with older boats. Probably better to have it out for a few weeks over the summer whan I am not about, as a mild precaution. Hull looked fine last time I had it out and I know a few owners in the US and no one has ever heard of any problems with this model.

I may pop over to the cowes boat lift and change the annode while they jet wash it and check the props.Other than that she stays in for the winter.Much better protected from sub zero temps.
PS, I do hope the Anchor jibe was not directed at me.
 
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Good download.

Im not too concerned .Boat has just turned 10 years old so I assume the layup would be less susceptable to problems than with older boats. Probably better to have it out for a few weeks over the summer whan I am not about, as a mild precaution. Hull looked fine last time I had it out and I know a few owners in the US and no one has ever heard of any problems with this model.

I may pop over to the cowes boat lift and change the annode while they jet wash it and check the props.Other than that she stays in for the winter.Much better protected from sub zero temps.
PS, I do hope the Anchor jibe was not directed at me.

Must have missed that one

Very interesting thread tho chaps
 
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