Hull dampness.

[ST840]

Hi all,
My Sealine has been recorded with hull dampness readings In the range of 10-20 (not sure of units). Ive been told that this is the higher end and a possible strip back of the hull may be needed. There are no signs of osmosis !
My question is , seeing as ive been roughly quoted £6-10K for a hull strip, dry out and re coat what are the implications of just leaving it and doing nothing ??
I have heard that on the continant they never worry about these things and that we brits tend to be over cautious .
I don't want to get ripped off and end up doing work that MAY not be necessary.

Many thanks !

 

[jfm]

Yup, I'd do nothing. If you hadn't been told about the 10-20, which is quite a wide range btw, you wouldn't know. There are no symptoms, right? So just carry on boating imho

 

[omega2]

Was this found in the course of a survey? I rather fancy it was, when were the readings taken? shortly after lifting out I'll wager, of course it reads damp it's a boat, and none to my knowledge have sank from this alleged osmosis. Of course if you can see black blisters and when pressed they weep water then you will need to do something, usually rub them off and treat with gelshield otherwise leave alone and as said enjoy yourself.

 

[Medskipper]

Yep, agree with all the above, but if you are really concerned about it have the boat lifted and leave it on dry land for a year or so! Or take it to Spain and leave it on dry land for only three months!

 

[Bbroomlea]

Our old S24 had higher readings than that and no blisters. 4 years later it had a some blisters when it was surveyed by the prospective owners. I saw the survey and the moisture readings were lower than what I had 4 years previously.

When I surveyed the boat to purchase it was lifted and within an hour or less on a very wet day readings were taken. When it was surveyed for sale it was done after being out for 24 hrs and in the summer. The lower reading had blisters and mine didn't. Nothing was knocked off the agreed price for it either - after all it was a 1996 boat and after sitting in fresh water for 17 years to be expected according to the surveyor.

I cannot remember now what the readings were on our S28 last year when we bought her but they were 5-10 in general with some areas a little higher and some 0-10. Our survey report was very good for the age (2002).

What age and model is your Sealine?

At the end of the day though I would not let it bother me at all - as long as there is no delamination, plate sized blisters or the hull covered in 1000's of tiny blisters then ignore it. It will cost no more to fix 5 years from now than it will tomorrow and you keep your money to spend on things far more important.

 

[Deleted User YDKXO]

Hi all,
My Sealine has been recorded with hull dampness readings In the range of 10-20 (not sure of units). Ive been told that this is the higher end and a possible strip back of the hull may be needed. There are no signs of osmosis !
My question is , seeing as ive been roughly quoted £6-10K for a hull strip, dry out and re coat what are the implications of just leaving it and doing nothing ??
I have heard that on the continant they never worry about these things and that we brits tend to be over cautious .
I don't want to get ripped off and end up doing work that MAY not be necessary.

The figures in themselves are meaningless without knowing what the units are which as I understand it can be either % water or a scale specific to the moisture meter itself. I'm no expert but assuming that the figures of 10-20 refer to % water then they are probably on the high side because I have heard that figures around 10% are acceptable. However, before making any judgement you also need to know who reported these readings (qualified surveyor or the company trying to sell you the hull strip), where the readings were taken on the hull and very importantly how long after being lifted out of the water the readings were taken because moisture readings can reduce significantly after a few weeks out of the water. I agree with the other posters; I would definitely not sanction an expensive and probably unnecessary hull strip particularly if there are no obvious signs of blistering. If you are still worried, and assuming that the boat is out of the water at this time of year, wait a few weeks and have the hull moisture content remeasured by a qualified surveyor who is capable of commenting on the results with authority

 

[longjohnsilver]

Yup, I'd do nothing. If you hadn't been told about the 10-20, which is quite a wide range btw, you wouldn't know. There are no symptoms, right? So just carry on boating imho

Agree, but if you're worried just keep the boat out for a few months, preferably in spring/summer and take another reading. I'll wager the readings will be lower.

Why do anything when there's no problem?

 

[CX54WEK]

Is there any water in the bliges as this can give a false higher moisture reading.

If there is currently no sign of osmosis then there really isn't much point in getting it treated right now. The odd blister isn't really going to do any harm and will be of little detriment to the boat other then looking unsightly. You can locally treat and fill the blisters but this is really only for cosmetic reasons. As and when the problem becomes more extensive, then it is the time to start thinking about spending the money on a full treatment.

 

[Nick_H]

Just one thought, if there's no symptoms now, is it worth having the boat out for as long as possible to dry out, and then having the hull epoxy coated? If this helps to seal out moisture from re-entering the hull, then it may be a cheaper way of avoiding longer term problems. I've no idea if this is a good idea or not, but it may be worth discussing it with an osmosis expert.

 

[beejay190]

Dry Stack perhaps ?

 

[ST840]

Thanks for all the replies/advice so far (I am feeling more relaxed now).
She is an s28 1999 model. The readings were taken at time of survey and sale price adjusted accordingly.
I have had here stripped of anti foul and primer, she has been out of the water a month and the readings have stayed the same ( re tested last week ).
As I said there are no blisters etc and hull looks nice and straight !! ��

 

[longjohnsilver]

Just one thought, if there's no symptoms now, is it worth having the boat out for as long as possible to dry out, and then having the hull epoxy coated? If this helps to seal out moisture from re-entering the hull, then it may be a cheaper way of avoiding longer term problems. I've no idea if this is a good idea or not, but it may be worth discussing it with an osmosis expert.

Nick, not recommended, the end result is any moisture remains trapped and more likely to cause blistering. Don't ask how I know this...................

 

[CX54WEK]

Nick, not recommended, the end result is any moisture remains trapped and more likely to cause blistering. Don't ask how I know this...................

Our surveyor suggested the same last year when we were considering applying epoxy to ours.

The moisture readings on ours had climbed up in the six years we had owned the boat (not unexpectedly), and although it was giving readings lower then the OP's he suggested not to bother epoxy coating the hull as it would only compound any future problems.

In the end we stripped it of antifoul and primer, which was starting to build up too much for our liking, and then applied fresh primer and antifoul.

 

[Nick_H]

I have had here stripped of anti foul and primer

If you've already had her stripped, then I really think you should get some specialist advice on whether to do anything preventatively now, before you apply any new antifoul. Maybe a phone call to Osmotech in Hamble, or a discussion with your surveyor. LJS, I hear what you say, but maybe there is a technique to ensure the hull is dried out first (eg. radiant heaters or tented and de-humidified?)

 

[Deleted User YDKXO]

Thanks for all the replies/advice so far (I am feeling more relaxed now).
She is an s28 1999 model. The readings were taken at time of survey and sale price adjusted accordingly.
I have had here stripped of anti foul and primer, she has been out of the water a month and the readings have stayed the same ( re tested last week ).
As I said there are no blisters etc and hull looks nice and straight !! ��

If it was me, I would leave it another month and re-test it again to see whether the moisture readings improve. What is the history of the boat? Has it been lifted and stored on the hard for a few weeks every season or has to been permanently kept in the water for several seasons? If it has been kept in the water for a few years, it will take a longer time to dry out. Agree with NickH. It would be worth getting an alternative opinion from some experts like Osmotech http://www.osmotech.co.uk if you're on the S Coast

 

[longjohnsilver]

If you've already had her stripped, then I really think you should get some specialist advice on whether to do anything preventatively now, before you apply any new antifoul. Maybe a phone call to Osmotech in Hamble, or a discussion with your surveyor. LJS, I hear what you say, but maybe there is a technique to ensure the hull is dried out first (eg. radiant heaters or tented and de-humidified?)

You've moved on to the next stage now Nick. Different ball game if you dry it out properly, then epoxying makes sense. The drying process is not an easy (or quick) one.

 

[Bbroomlea]

Thanks for all the replies/advice so far (I am feeling more relaxed now).
She is an s28 1999 model. The readings were taken at time of survey and sale price adjusted accordingly.
I have had here stripped of anti foul and primer, she has been out of the water a month and the readings have stayed the same ( re tested last week ).
As I said there are no blisters etc and hull looks nice and straight !! ��

In that case do nothing! If she starts to seriously blister in the next few years then consider sorting it then. It may never get any worse than it is now, especially if you take her out each year. Even if you do get a few bubbles I would be inclined to do nothing. Come sale time you can see what happens - maybe you have to readjust what you would have spent, likely you would only pay 50% or best case contribute close to or nothing!! Its a gamble but you have a very low chance of paying more than you would if unnecessarily stripping the hull and paying the full cost yourself.

The brokers we have used in the past have said very few people walk away from a purchase for the sake of a damp hull or few blisters. Once they have invested the survey fee, crane costs etc usually a deal can be done. Unless structural surveyors will not recommend against purchase.