Possible cause of high moisture readings,

mickshep

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Over the last year and a half I've been restoring a Shipman 28 built in 1973, http://www.yachtsnet.co.uk/archives/shipman-28/shipman-28.htm Whilst there were no blisters whatsoever, the hull moisture levels where through the roof particularly in the keel and at the root of the skeg, My 1st step was to heavily sand the entire hull to 'open up' the surface and hopefully speed up the drying. After 6 months the moisture levels were very much reduced in the hull but remained very high in the keel and skeg area. As a last resort I ground the gel coat off the effected areas (Very easy with a circular flap disc fitted to angle grinder), Beneath the gel coat was a 6-8mm layer of 'car bodge' used as a fairing filler, This was satutated, 3 hrs with the grinder saw this removed to expose the GRP encapsulating the cast ballast keel and a substantial drop in the moisture readings, this same filler was evident in the other high reading areas. With this removed the entire hull was allowed to dry out to less than 5% on a sovereign meter, The keel is now re faired using GRP and the entire hull repainted with 6 heavy coats of high build epoxy, above the waterline is now awaiting the last coats of 2 pack polyurethene , Will it last? no idea but the moisture levels were well within the paint specs'. I've posted this as anyone else with stubborn areas of moisture might have a similar set up lurking beneath what appears to be gel coat, Mike.
 
Interesting story. I've had wood for a long time - it IS maintenance, but actually it's all quite easy.

Heading to GRP, rather daunted by the need to learn a new set of skills. Oh well

SmileyG
 
To be honest I'm feeling pretty happy, as I understand it blistering is the result of water reacting with uncured chemicals in the substrate, my hull was very wet but no blisters after 34yrs makes me think she might never develop them, now she's really dry and has been coated with multiple coats of epoxy and will winter ashore I'm hoping she'll be good for another 34yrs, Mike
 
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