Winter liftout

[dhobyb]

I have a 42" yacht, and I will be lifting her on to the hard for a while during the winter, is there a recommended time period for being out, I am told it is to let the hull dry out but cannot find any information, I am just going on what the old guys tell me. So the question is is 6 weeks enough?

 

[theoldsalt]

Wood, GRP, Ferro, Steel ?

Sorry, just looked at your profile, It's GRP.

Why do you want to "dry out" the hull. If it is just to antifoul then a day is enough, depending on weather. If to epoxy then much longer.

 

[charles_reed]

All hulls (except metal) take up water - GRP is no exception and unless you've epoxied the gel coat (6 coats of gelshield is usual) you'll need about 12-26 weeks in a fairly low-humidity situation to get most of the water out (if you wanted to put on your gelshield).
However if you're just renewing the antifouling, that can be put on almost immediately.

So to "dry out" 6 weeks is totally inadequate - to replace the antifoul 6 days is more in line.

 

[pvb]

I've never been able to understand the theory that a boat can "dry out" in a British winter! Unless you need to antifoul, change anodes, etc, leave it in the water and save your money.

 

[Rossynant]

Much depends on weather and hull thickness and paint on it (and type of resin used, but that's unknown), in UK you would need a shed or such and 6 months rather than weeks. Dry air and high temperature is needed, I would say no way to dry in UK with no shelter and paint on bottom.
Not much familiar with moisture meters but after a year ashore had "wet" reading - way too much, as I understand this is indication of serious problems Bottom has epoxy paint on (not a 'treatment'), no osmosis as such. But area of watertank (cannot dry) was even more wet so some drying must have taken place.

As for reason to "dry out in winter" must say there may be something in it. In Holland two identical boats (Contest 33, from series with resin known of osmosis problems) there was one normally wintered ashore in nice condition - another that was left in water for 7 years had huge deep voids in laminate the size of a hand, GRP could be just scratched out. Most close to waterline, maybe from freezing damage?

If for osmosis or other repairs - paints (and gelcoat preferably) should be removed, some heat or ventilation provided. Inside hull as well.

 

[chrishelen]

All hulls (except metal) take up water - GRP is no exception and unless you've epoxied the gel coat (6 coats of gelshield is usual) you'll need about 12-26 weeks in a fairly low-humidity situation to get most of the water out (if you wanted to put on your gelshield).
However if you're just renewing the antifouling, that can be put on almost immediately.

So to "dry out" 6 weeks is totally inadequate - to replace the antifoul 6 days is more in line.

A plastic boat will never dry out unless you remove the gelcoat and put heat into it,save your dosh and just anti foul as long as osmosis free and put back in.

 

[r_h]

I note that the OP has Jeanneau 42DS - a very recent boat. The resins used since the late 1980s/early 1990s means water retention will be minimal (to all practical intents non-existant) and there's nothing to worry about.

 

[Mistroma]

I also have a 42DS and it is laid up ashore each winter, as was my previous boat. But that's mainly a lifestyle choice as SWMBO doesn't like sailing when it is cold and wet. So I do odd bit of maintenance ashore and we sail in summer (when Scotland is usually still wet but a bit warmer).

I've never really believed the drying out argument for similar reasons to those mentioned above. However, I think that progression of osmosis is proportional to time afloat. I'm ignoring construction, quality, temperature and other factors. You can't do much about most of these apart from strip the gel coat and start again or buy a different boat.

If you have a boat that would get osmosis after 6 years afloat (random example) then it might last 12 years if only afloat 50% of the time. Huge over-simplification (progression might not be linear) but you get the general idea.

So it will probably help to haul out for 6 months if your boat is likely to get osmosis. But you'll probably never know if it was worthwhile as the boat might never develop it anyway (being relatively modern).

 

[Rossynant]

In warm waters (Florida) 'more modern better resin' boat can have osmosis in 10 years or so. Some makes seem to be resistant though.
An old UK boat (good make, normally having no problem) got blisters after 4 years in Gibraltar. But wouldn't worry in Scotland

 

[xyachtdave]

I've never been able to understand the theory that a boat can "dry out" in a British winter! Unless you need to antifoul, change anodes, etc, leave it in the water and save your money.

PVB is spot on here.

I reckon a boat with moisture in the hull is better off in the water than sitting around in the freezing cold 'drying out'.

Get her out of the water for 6 months in Turkey during their summer and maybe it might help!

 

[yoda]

You have a modern boat so the reality is that there is no drying out to do. Take her out for long enough to do the necessary maintenance. On the point of maintenance, I don't believe the 42DS is fitted with a hull anode as standard and therefore the skeg can easily be suseptible to electrolysis. I believe the skeg is bonded back to the engine and hence to the shaft anode which protects prop and skeg. A good friend had to replace his skeg because he lost his shaft anode without knowing and was therefor unprotected in the water for some time. Because of thishe has added a hull anode to avoid the possibility of protection being lost.

Yoda

 

[wotayottie]

Its amazing the amount of unqualified rubbish that some subjects can bring about.

Even modern grp laminates that are well made will absorb some water. But there are two sorts of water absorption - "getting a bit wet" and osmosis. The former is a simple absorption process, the latter is a chemical degradation process. In the case of the former the boat can dry out. With the latter it wont dry out because the chemical products that cause the blistering are hygroscopic. Whether a wet boat can dry out is one good test of whether it has osmosis.

And just as your wife's washing can dry on the line in winter, so a boats hull can dry out. Only when its raining and the water is running down the hull will that process stop altogether - on days like today it will dry.

How long depends on how wet and how thick the laminate is and a few other factors as well. So no one can give you a specific answer.

Osmotic degradation is like most chemical processes time and temperature dependant. If your boat is in the water for half the year then it will take roughly twice as many years to get osmosis. It will get the pox faster in fresh water than in salt. It will get it faster in tropical waters than in Scotland. If getting the pox is what worries you then keep the boat out of the water every winter and sell at 10 years old to replace with a new boat.

 

[theoldsalt]

I think most owners who lift out their boats for the winter do it for safety reasons and not to dry out the hull.

I feel that my boat is safer ashore since I have no intention of useing it from November to April. This also makes routine maintenance easier as I can do it at my leisure rather than rushing it for the short time that it might be ashore if wintered afloat.

Many people also have exposed moorings that may be entirely unsuitable for a boat during lengthy winter gales.

 

[MoodySabre]

I've never been able to understand the theory that a boat can "dry out" in a British winter! Unless you need to antifoul, change anodes, etc, leave it in the water and save your money.

+1

If you are in a marina then the boat will be safer in the water, won't freeze up (well not down here). Come out for a week in warmer weather and do the necessary.

That's my theory and I'm sticking to it.

 

[pvb]

Come out for a week in warmer weather and do the necessary.

Spot on! I get the boat lifted in the summer for a week, every 2 years, to antifoul and polish. Not only is the weather much nicer for working on it, but the lift/relaunch costs are a fraction of the winter rates!

 

[Phoenix of Hamble]

Spot on! I get the boat lifted in the summer for a week, every 2 years, to antifoul and polish. Not only is the weather much nicer for working on it, but the lift/relaunch costs are a fraction of the winter rates!

+1

a week or two out when the lifts are cheaper....

IMHO the boat is much safer in the water than on props when the winter gales comes through.