Swan 43 - hull moisture

"Reindeer" is a 1969 Swan 43. Her hull was peeled below the waterline six months ago in preparation for osmosis treatment. I was hoping that the hull would have dried out a little by now, but the readings are still mostly off the scale. The yard's plan is now to use vacuum technology to dry her out, but I am anxious that them whole season could be lost.

Has anyone had a similar problem? I'd welcome any advice on this.

Jack Meredith

Dear Jack,

Well, this can take a LONG time! My 47 #20 took 15 month to dry out! Washed down with hot water app.10 times!.........in April we will sail again. DON´T start before it is 100 % dry unless you want to do all the work again in 2 or 3 years!! Don´t forget you bourght a Swan! The hull is twice as thick as new boats, so be cool! It pays off in the end!

Many regards

Carsten Overland

Hello Jack:

My Swan 43 (#46) went through a similar process of osmosis treatment below the waterline.  Although my boat's laminate was in very good shape with no blisters or de-laminations the mositure readings were on the high end of the scale.

Before the osmosis treatment could be done properly the gel coat and first couple of layers of laminate were mechanically peeled.  This was followed by the boat's laminate force dryed in a shed with infra-red heaters going for approximately 3 weeks non-stop.  After acceptable levels of dryness was achieved the the osmosis protectives were applied.

As noted by the previous responder, do not rush the process.  It should be done correctly following the osmosis treatment manufacturer's recommended guidelines.  You certainly do not want to have to do the osmosis treatment.

I have attached a photo of the boat during the drying porcess. Good luck

Hiro

Many thanks for your advice, Carsten. I agree with your approach - better to do the job properly, even if that means a lost season.

Thanks Hiro. I am thinking of peeling back a second layer. Did you add new cloth when you recoated?

Jack

Reley on professionals who have done it several times and use known manufacturers' material and methods. My experience on my Swan 36 from 1967 was that after peeling to dry the hull under a tent inside a house with 11kW heaters for 3 months 24hrs a day and keeping the surface heat about 49 C. The work teached us to rinse the hull several times a week, the last two weeks every day! The rinsing showed clear effect on moisture when measured. The odor of acetic acid disappears when it is out of the hull. By the way, there are several opinions about the origin of moisture in the old hulls: some expert people think it is not only an effect of moisture coming from outside(or inside the boat) but rather an effect of old methods, not exact amount of resin components, aceton use when cleaning the instruments, low temperature, etc. But the treatment is the same. So, heat and rinse.

Dear all,

on our 41/022 we did a complete osmosis treatment some 25 years ago. It has been OK until now with only a few blisters in one place or another. Now it is starting again in some places so will have to be redone.

The only point we missed was to make sure that peeling the hull and subsequent painting was actually done ABOVE the waterline, and NOT ON the water line. As most of our boat are getting heavier than originally,  it means you must peel, and paint up to the second blue line, or even better INCLUDING the second blue line. Which is not what can be seen on the picture included in this link.

Kind regards to all, and fair winds.