When did osmosis start ?

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zambant

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Well not quite the right question but clearly modern boats dont "seem" to suffer from it.

So what I reallty am asking what year did resin or the process change to stop or reduce this please?

Any one know? :confused:

Thanks

John
 
This article may make it a little clearer :eek:

If you read through it it seems to point to the way they are constructed in the first place and how the layers were laid.

.
 
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I think

BJ4U said:
This article may make it a little clearer :eek:

If you read through it it seems to point to the way they are constructed in the first place and how the layers were laid.

.
Click to expand...

I think it emerged sometime between when they stopped making Mirror offshores and started making Centaurs

I would say 1973

Slugs have never suffered, I had a Sonata that had it really bad - cost me £4,000 for a peal and poxy

on a boat that cost us £5,000

at the end it was worth £4,500

but I was young, rich and stupid then

no longer am I rich but I have still retained my youthful stupidity

Dylan
 
There is no definitive start and end date. The era where it was most common on a whole range of boats was 1970's to 80's and became common in the latter part of that period - that is when boats started to age. Because problems can take years to show, boats from that era will still be suspect.

Changes in materials and particularly processes in the last 20 years or so have resulted in a significant reduction in such problems, but of course there may still be underlying issues to come out in the future.
 
the slug

Tranona said:
There is no definitive start and end date. The era where it was most common on a whole range of boats was 1970's to 80's and became common in the latter part of that period - that is when boats started to age. Because problems can take years to show, boats from that era will still be suspect.

Changes in materials and particularly processes in the last 20 years or so have resulted in a significant reduction in such problems, but of course there may still be underlying issues to come out in the future.
Click to expand...

the slug is rising in value now that we have established that it was designed and built before they invented osmosis
 
I think it is down to the quality of the hull manufacture (materials and proceses) as much as age.

A lot of Westerlies seem to suffer from osmosis but it is rare in a Moody.
 
Not just boats- I used to have a 1976 Matra Bagheera sports car, which had osmosis bubbles on the roof and bonnet.
 
It takes a while for the water to be absorbed, but I have seen a few newer boats with osmosis or even having gel coat peels, so I am not so sure the rate will be significantly less on modern boats. It's a pity more manufactures are not producing epoxy hulls.
 
tobermoryphil said:
Not just boats- I used to have a 1976 Matra Bagheera sports car, which had osmosis bubbles on the roof and bonnet.
Click to expand...

Quite right and today it is still affecting some modern Lotus cars with grp bodies made in France. By Beneteau?? :D

I read somewhere that osmosis was first spotted when it appeared in the grp roofs they built in the early days for swimming pools. Not only were they always wet from condensation but they were also fairly warm. I also read that it is an inevitable function of the structure of the ortho poly molecules made worse by bad construction but not avoided altogether even by good construction. One expert used to reckon in the 80s that 90% of boats more than 10 years old had some degree of osmosis and certainly when I once used my moisture meter on the hulls of most of our club boats after they had been ashore for 6 months, all but a very smalll proportion were wet but with only a few showing blisters.

The answer to the OPs original question is to buy an epoxy boat. But most grp boats seem to have been made with a different and better gel coat resin after the early 90s
 
The Nicholson 36 built in 1969 and moulded by Halmatic had boat pox like there was no tomorrow. Early fibreglass construction with alloy ribs to make it stronger.
 
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It must be a function of the manufacturing process as much as materials. Just as a random bit of empirical evidence - we have a Colvic Watson 34 from 1977 that hasn't a trace of osmosis. Recently there was a CW32 for sale by the local brokers from the mid 80's - every square foot of the underwater area had a collection of vinegar smelling blisters, even the waterline and a few inches above that would hardly ever get wet had mini blisters. The owner regularly had the boat out for the winter but clearly there was something in the process or mix of chemicals that made it susceptible.
 
SHUG said:
The Nicholson 36 built in 1969 and moulded by Halmatic had boat pox like there was no tomorrow. Early fibreglass construction with alloy ribs to make it stronger.
Click to expand...
Nic 32s also famous for "having osmosis" - some of these boats, first built in 1962, have had more than one "full osmosis treatment" - probably totally unnecessary except to render them more easily saleable (as opposed to sailable) as the hulls are massively heavily overbuilt by modern standards - I drilled a hole in one once.

I also owned a similar era heavy long-keeled Cheoy Lee that had quite a lot of pound-coin-sized blisters when I bought it. Individually ground out and filled, and a few more 12 years later when I sold it after having spent virtually the whole time in warmish water. If I found similar sized blisters in a modern lightly built boat I might worry, but not on most 1960s/70s (ie overbuilt) boats.
 
Having done a lot of work on fibreglass over the years I was always searching for the cause of Osmosis, I must have spent countless hours pondering, reding and researching the subject.

My findings have led me to believe the cause of Osmosis is in fact the resin supplied during during world wide fuel shortages, in the 70's and 80's.

Less fuel being processed meant less resin getting to the world market, I believe this led to modified extraction processes that in turn resulted with a poorer quality resin being supplied world wide.

The time laps is a very good match for the two periods now recognised as the 'bad years'.

The good news in all of this is that it changed many methods and practices and processes used to construct fibreglass hulls.

I also predict the next world fuel shortage that lasts as long as the 70's and 80's did will produce the same results.

Good luck and fair winds. :)
 
I knew someone with a boat moulded in the late 1970's, which had stood outside uncompleted for a good couple of years before he got her.

There was osmosis at the bilge where rainwater had collected, and on the hull where the ( rain absorbent, wet ) carpet-covered cradle steadies had been in contact; all without ever seeing the 'oggin.
 
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