Survey / Water content question

[BarryD]

Hi - the survey I've recently had done reported readings of 15 to 17 below the waterline and 5 above on the scale of 0 to 25 - no evidence of osmosis or blistering. However the surveyor recommends that the boat should be lifted and allowed to dry all winter.

It spent 6 weeks of the summer out whilst it had an engine change and was stripped and re anti-fouled, andoes etc.. then so if it was going to dry out it would have done so at the time. BTW its GRP and 11 years old.

Should I worry, should I heed his advice. I'd like to leave it afloat (South Coast Marina) so that I can use it. Prehaps with a lift, anode inspection and pressure wash in Spring. Next Winter it will come out for a longer period.

Any guidence for a novice?

Barry D.

 

[peterg]

Hi Barry, you can't get away from us stinkboaters by posting on a different forum you know, we have eyes everywhere!

To answer your question from my limited knowledge, the consensus seems to be to take a boat out of the water for about 3 months every 2 years to allow it to dry out and for usual maintenance (anti-foul etc.). As your boat is 11 years old and may have been 'left in' for some time prior to this summer it may be that it wasn't allowed to dry out as much as was needed (it'll never get completely dry).

Basically, if you leave it in now and take it out for Jan-Feb it won't harm it but when you test again before relaunching you may find it has reduced the moisture content a bit more. Don't worry too much though, there's plenty of people who leave their boat in all year round with just a short lift every year (2-3 weeks) and they don't seem to have any more problems than the rest of us - each boat will have taken up the gelcoat and curing resins fractionally differently due to atmospheric conditions so some will naturally have a slightly higher moisture content than the same model made 2 months (or even 2 days!) later.

Cheers Peter

 

[Guest]

We have two factors here that are common mistakes :

1. The readings, even though taken in reference against top-sides, are meaningless unless we know exactly what machine was used etc.......
2. Lifting out in winter or any other time does not 'dry-out' a hull strata ... if osmosis has occured, the fluid is too dense to release and that is what produces the blisters eventually - the pressure build up.

Thats putting it very simply, there are many other factors involved.

Now for your boat, we can assume that the hull is 'wet', ie taken up some moisture and produced high readings. Accepted and may be Osmosis, but it could also be moisture trapped in antifouling layer if not properly removed before metering, it could be moisture internally if using a good meter such as Tramex .......

The notion that lack of lift-out has provoked this - wrong.

If there are no signs of blistering, the hull is sound with no cracks / crazing, or otherwise - you could leave it in - I leave my boat in 2 out of 3 winters, and I have high readings AND I'm a surveyor !!! BUT I do expect that later I will have to do something about the high moisture .... for me, which I do not advocate for others - it can wait until its blistered !!

As to summer lift out against winter ....... Summer can at times actually delay drying out due to higher humidity, winter can shorten the time if its dry period. So there is no definite rule over this.

Finally- as I have posted before on this site - I know of no boat that has been LOST due to osmosis ...... if anyone can provide evidene and data to the contrary - I would be the first to be very interested .........

 

[tonyleigh]

Thank you for some good comments. Some 13 years ago I looked to buy a little Van de Stadt Splinte which on inspection turned out to to be a mass of blisters. I then discovered it was renowned as an osmosis riddled hull, had not been out of the water for 12 years, and was expected to sink as soon as the weather dropped to freezing. I didn't buy! That boat has changed hands 3 or 4 times since and is still being sailed and spends 12 mths a year on a swinging mooring!!!! My own hull spends 6mths a year ashore, was epoxied as soon as I bought it, is scrutinised closely for the slightest hull damage and has very low moisture readings. I maintain it like this I guess out of pride but I too would be very interested to hear true tales of osmosis leading to sinking.

 

[paulplatts]

My experience is that surveyors tend to take a cautious approach on moisture content and will almost always find moisture in an older hull. My boat has been taken out of the water every winter for many years, but still a recent survey suggested that there was an amount of water present. If there are no obvious blisters, hollow sounds when knocking on the hull etc. then there should be no problems with moisture significantly weakening or delaminating the hull. Then a little bit of moisture can not be avoided. Being a little cynical you could think that a surveyor has to find moisture in order to justify his fees - or then again ......