Osmotic Blister Repair is a very involved process. To start with, blisters can appear as very few small ones or they can manifest to the more extreme, many large ones. In any case, the cure begins with removal of the gelcoat and 1st layer of matt (fiberglass) on the hull. This is usually done with a gel-planing machine that strips these layers off, much like a wood planer cleans a plank. Once the hull is stripped, than the decision needs to made if the hull also needs sandblasting. Sandblasting is needed only if the hull substrate has many air pockets between the laminates. These air pockets must be removed because they hold water and glycol, a bi-product of the polyester resin used to build the boat. The sandblasting that we perform is done with a freshwater assist, which washes the sodium chloride and Glycol from the substrate, as it blasts. This is important as both of these by products hold water and we will be tenting the hull-bottom and interior with dehumidifiers to remove moisture. If either glycol or sodium chloride remain on the surface, than moisture also remains. During the process, readings of the hull moisture are taken weekly to ensure proper water evacuation. Dehumidifying can be adjusted accordingly. The tent is removed in the middle of the entire process, when the hull reaches Approximately 10 % moisture using a Sovereign Moisture meter, to allow us to pressure wash the bottom one more time to insure Glycol and salt removal. The tent is then added back, along with the dehumidifiers, until the hull reaches a 3-5 % moisture content. Then the real work begins.
If everything went as planned it took us about 1 1/2 months to dry the hull out. We will now start the barrier coat process which is modified slightly from boat to boat. Generally, we start out sanding the bottom with 40 grit sandpaper. We then wipe the hull with alcohol prior to the sealing process. The hull is sealed with a 2 part epoxy putty/resin that is applied at a specified thickness, and sanded prior to epoxy primer application. The epoxy (barrier coat) primer is then applied to keep the moisture from getting into the hull again. The barrier coat works by using a micro plate technology that was developed by one of the primer manufactures. This primer is then sanded to 80 grit prior to the bottom paint application. Bottom paint of your choice can be used at this time. It generally takes 1-2 wks to complete the new barrier coat process, for a total of approximately 8 weeks yard time (weather permitting). Call or E-mail Gable Enterprises for a Quote.