Osmosis - Nicholson 35

[simonoakes]

I am thinking of buying a Nicholson 35 that has been laid up afloat on a freshwater mooring for the past 10 years, during this time she has not been slipped or painted. Should I be concerned about osmosis? Is osmosis more or less prevalent in freshwater? How can I check if osmosis will be a future problem? If I was to buy the boat should I put her ashore for a period of time to dry out? Maybe epoxy the bottom?

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[muchy_]

People in this country make such a big deal about osmosis. I would be more worried about the state of the engine(s) and mechanicals. I think its a safe bet to say that it will have some osmosis to a greater or lesser degree but its really not that much of a problem. Just take the boat out of the water and if you find any blisters on the bottom dig them out, dry it with a hair dryer, fill with Isopon or similar, sand and repaint. Osmosis is only a cosmetic problem and to my knowledge no boat has ever sank due to it.

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[maxi]

Yes, with a Nicholson there is a long history of osmosis although they are a great boat in every other respect. Osmosis is far more prevalent in fresh water than in salt, and it is not merely a cosmetic probem of no consequence. Probably it is over-hyped and probably no boat has sunk as a conseqence of osmosis, but the effect on values and re-sale is far from being of little consequence.
Short term (apparent) drying of the hull and digging out the blisters will solve little or nothing unless the products of hydrolysis are fully removed before epoxy coating. Think this one through carefully.
If you buy her, enjoy her, she is a true classic.

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[Birdseye]

As the owner of a boat purchased with osmosis, I would agree with what Maxi has said. There are more serious problems (water in balsa sandwich decks for example) but you shouldnt ignore osmosis or bodge a repair. It will affect the price you should pay, and it does take considerable time to deal with so you might lose a season quite easily.

However, all unprotected polyester boats will get osmosis sooner or later and to varying degrees - its inherent in the chemistry of the resin. So if you are looking at older boast like the Nic, you should expect it.



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[grahama]

We purchased a Nic several years ago, the boat was a live aboard and had been mostly in sea water all year round for the last decade, the moisture reading we're around the 10 to 15 mark - still in the green sector of the moisture instrument though, not sure of the make of instrument ( so a bit of damp but nothing to worry about yet - or so I'm told), not bad for 25 years old. As previous responses there's lot of other bits to worry about, we've put a new engine and gearbox in ours- the list continues!!.
Never mind old boats having osmosis, I was talking to a chap recently that was having his 5 year old french boat stripped and treated as the moisture readings were at lowest 30 (red sector started on this instrument at 20) and many parts we're heading off scale! Only thing in his favour is that I think the warrently was picking up the tab.
They're a great boat and you can at least feel secure that she'll look after you when the going gets tough, ours has and I'm no sailing expert.

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[grahama]

Out of interest what is the long history with Nicholsons and osmosis?, does it effect certain sizes of boats or certain years of build??

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[vyv_cox]

My Sadler 34 has been kept afloat in fresh water for the past six years. There is a small amount of osmosis blistering but definitely not anything to be greatly concerned about. The vast majority of boats in Holland are kept in fresh water and more than 50% do not haul out for winter storage. Osmosis is no more of a problem here than it is in UK.

Drying out ashore for six months will not do any harm but I wouldn't miss any sailing time to do it. Epoxy coating should only be applied to a dry hull.

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[muchy_]

Yes, I agree that osmosis will affect the resale value but you have only lost money if you paid the full value for it in the first place. If you pay a reduced amount because of the osmosis then you wont lose any and if you patch up the osmosis yourself the boat is unlikely to fall apart around your ears.

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[Hushinish]

I have just purchased a 15 year old 24 footer that has never been in the water, would it be prudent to epoxy the hull before the maiden vogage? The red gellcoat has turned brown in one place approx 30 cm diameter, what might cause this? Also, possibly a silly question, but does one antifoul a hull which is to be kept in freshwater?

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[Strathglass]

Yes, what and yes.

YES.
Seal the gelcoat with an anti osmosis treatment (West, Blades, international or any other BEFORE launching.

What ?. Could it be some ferous material which has stained the hull

YES The chances of osmosis are much higher in fresh water.

BTW my hull is over 20 years old and has never been in the water. I have already purchased the material for the Blades treatment. I would not consider launching an older hull without treatment.

Older hulls were manufactured with inferior (in terms of osmosis) materials and an old hull is virtually guarenteed to suffer from osmosis at some time.

Perhaps not what you wanted to hear, but

Regards

Iain

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[Twister_Ken]

Freshwater antifoul

It exists and it's different from saltwater antifoul. I know Blakes offer it, and possibly other mfgs do too.

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[vyv_cox]

Re: Freshwater antifoul

Fouling doesn't really occur in fresh water. Over a period of time a black slime deposits over the underwater surfaces, very easily removed by light scrubbing. After long periods it appears from the hulls of some of my neighbours' boats that the intensity barely increases at all.

The great thing about keeping a boat in fresh water is that it kills off the salt water fouling, which then falls off. Seems to be the ultimate protection, and green, too.

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