My boat, a lift keel Sonata, had a survey in 1997, by the previous owner which showed moisture readings of between 15 and 20 on a Sovereign meter (whatever one of those is). The surveyor recommend all sorts of Osmosis treatment – none of which was carried out.
I have had the boat for a while – can see no signs of blisters. Am I right to happily ignore the survey or should I do something.
If there are no blisters or delamination, then all you have is a weight problem, not a strength problem, and even some blisters will not materially affect the strength. Probably you should ignore it, unless you have the facility to leave the boat out of the water in a dry environment for about 3 months, after removing all the anti-fouling paint.
When the reading on a soveriegn meter is appreciably lower, then cover the outside of the hull with 5 coats of interprotect 2000 or eqivalent, with two coats on the inside, and the hull will then last longer than you.
Treatment when there are already severe blisters won’t take any longer, but will be significantly harder work, and could be costly if you pay someone to do it. Since even a very smart Sonata is only worth around 5000-6000 pounds, it isn’t worth the effort.
Water in the hull doesn’t automatically create osmotic blisters. The next stage is for this water to react with uncured chemicals of the resin mix, and whether these exist in any significant quantity will depend on how much care the layup received, and what the temperature and humidity was at the time. If such chemicals do exist, then eventually the chemical reaction with the water will draw in more water (by osmosis) until such pressure is created between the laminate and the gelcoat that it will delaminate outwards causing the typical bubble.
Since your boat has a lifting keel, she is quite easily trailerable, and with mast removed and keel retracted, should almost fit in a typical garage. Extend this with a frame and cover, and, stripped of paint below the water line, leave her in this enclosure with a dehumidifier running all the time, for several months over the winter. A heater would also be useful to increase the evaporation. You can then epoxy and be pretty sure she will last for years.
Or alternatively, just ignore it and enjoy!