Posted by Bengt Blomberg on April 13, 2002 at 16:11:22:
In Reply to: Treating osmosis with HotVac? posted by Robin Wallman on April 10, 2002 at 07:28:37:
: Hello! I am looking into buying a Diva 355 (kevlar reinforced GRP sandwich hull and ISO-gelcoat) built 1993. It is sold in Holland. A survey shoved 17 blisters on the port side and 5 to starbord. The hull has previously been treated with epoxy. Measuring showed hi moisture levels all over the UW-body. The broker suggested a complete treatment using the HotVac method (the company leaves a five year guarantee). This treatment, he suggested, would cost approximately 5000-6000 Euro. My question then, is the boat worth buying and will the HotVac solve the problem? Many thanks
The way you describes the blisters, I fear delaminations below. Either between the kevlar and the underlaying layer or between laminate and core. The last is mostly easy to detect while the core does end some distance from the lowest bottom. If the lower part of the blistered area formes a straight line along the hull, there will be a delamination.
Otherwise the only way to find out the laminate status is to use the tip of a 1,5" drill bit to make some conical holes down to the core in the blistered area and check for acidity or bleeding fluid from eventally affected layers. The holes can then be filled with an epoxy filler which becomes stronger than the laminate itself.
If you are not allowed to do such a drillig you better refrain from buying the hull. Even with HotVac the treatment is a bit trickier than on a hull without kevlar and there is a risk, that the normal price offer you have got becomes much higher if delaminations are found during the treatment.
If you are allowed to drill you are welcome to e-mail me at email@example.com and describe what you have found. If you have a digital camera you can send me some pictures of the holes taken at about 5 cm distance. Then I can blow them up for closer inspection. Then you will get advise from both me and the HotVac technicians.
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