Just how bad is a moisture reading of 23?

[charles_reed]

I don't think it would be necessary to scrape off the epoxy in order to get an accurate reading - after all, GRP is just epoxy loaded with glass fibres. Surveyors do scrape off some anti-fouling to get at the hull for examination and readings - I assume that the chemicals in the anti-fouling interfere with the meters.

Polyester - a world of difference.
Though I agree with the conclusion

 

[contessaman]

I thought the whole point in taking moisture readings above and below the waterline was so that you can compare them. Its not the absolute value thats important (although clearly the lower the better) but the diference in readings between the topsides and below the waterline. That relative or delta figure, combined with checking for blisters and sounding for delamination being the primary tools for identifying advanced osmosis.

If you are buying a rock bottom price boat and arent looking for resale value then I would not be concerned with moisture or blisters, the only thing you need worry about is delamination - and only structural delamination at that.

You can test for the latter by percussion testing the hull with a plastic hammer or even the handle of a screwdriver. A sharp crisp rapport is what you want to hear.

Osmosis doesnt sink boats. Sadly the hype and panic caused by the sight of the odd blister now has such a firm grip of the sailing community that the mere mention of it wipes 1000s off the value of a boat. To that end all you need to worry about is that you dont pay too much for the boat or spend too much making it palacial down below only to be dissapointed when it comes to selling.

good luck and go for it next time, you would have gutted that cabin by now and be well into the fit-out!