Osmotic observations
These are based on THREE blister jobs that I have done, one poorly, one so so, and one well (with the benefit of good advice and experience). Periferally, I have also been involved with several other jobs done by friends. In answer to your questions, yes, drying does help and it can take months. My "good" job included about seven months in the Sonora dessert! And yes, a good barrier coat does work. Apart from all the normal things, I discovered the following from experience and very close questions to the technical types (not the sales people) at the blister repair systems manufacturers. 1) Most systems specify ten to twenty mils thickness....in fact, you are better off considering twenty to be the minimum and you won't go wrong up to forty mils. The thicker, the better, so start off by planning on TWICE the number of coats or thickness. 2) Do everything you can to eliminate water absorbtion in the bilge. This can take the form of a dry bilge, or a barrier coated bilge, or, better yet, both. 3) Run the barrier coat about six inches abover the waterline. Most boatyards barely get to the bootstripe, so it is like pulling teeth if you hire the job out. Plan on putting on a new bootstripe to cover the top of the barrier coat. 4) After you have exposed the laminate (either the whole thing or if you patch), rinse the laminate frequently during the drying period. This keeps the material that weeps from drying and effectively sealing the laminate, which keeps it from drying. Don't be afraid to scrub. 5) If you are patching, grind away an area several inches in radius around each blister. It will dry better, and the feathering and fairing are much easier. 7) You are giving the boat a new skin, so have a strategy for dealing with through-hulls, and other awkward areas. Ideally, you will remove these, but it is not always easy or necessary. 6) Read the directions, several times, and feel free to call the techs. They love to talk about their technology. 7) If you have not done any fiberglass or gelcoat work, go slow and easy. Use less material and more coats, rather than overdoing a particular coat. This will vastly ease the fairing process. 8) Do the best job you can. This is a horrifically tedious project, one you don't want to repeat. Don't skimp or be sloppy. On the other hand, don't let "perfect" be the enemy of the "good". GOOD LUCK.
