method for fast blister repair which was published in Epoxyworks Magazine #30. I worked this spring to get the gelcoat blisters opened up with a 3/4" counter-sinking bit. I needed two of them to get through everything, and probably could have moved faster with three. Fiberglass dulls them very quickly. Fortunately, all of my blisters were superficial, and none would need laminate grinding.
Today I loaded my caulk gun with a tube of West Six/10 Epoxy Adhesive and went to work on the voids. I used a typical West yellow spreader to smooth the epoxy after injecting it into the hole. I tried to build it up a little higher than necessary, although I'm not 100% sure whether or not I was successful. I'll have to wait until I sand the hull to know for sure whether it worked or if I'll need a second coat.
This process is of great interest to me because it, in theory, eliminates the need for a complete strip of the hull, and it eliminates the need for a barrier coat when done. Six/10 is thickened with fumed silica which works similarly to a barrier coat additive, thus saving a step. I also really appreciated not having to keep going back to mix up new batches of epoxy. Finally, there's no way I could have kept as much control over the repair slopping epoxy on with a spreader. The caulk tube allows addictive control of the placement and quantity.
My first working observation was that it is really, really, hard to see how much is built up. It's nothing like epoxy thickened with silica, or fairing compound. I was surprised at how thin the Six/10 was, but I'm glad as I could see it has saturated the material in the void so I know I was able to get a strong bond.
A tip if you are considering doing this repair: Spend a little extra money and buy one of the heavy duty caulk guns that has more leverage and more ergonomic handles. I used a cheap gun, and while it worked fine I could barely move my hands when I was done. It takes a fair amount of force to keep that static mixer charged (although it does work great!).
At the end of the day I had completed about 2/3 of the boat and used two tubes. You can see the volume of blisters in the photo, so I'm not at all disappointed with the coverage. This stuff is more expensive per once than other epoxy options, but wen you compare the cost savings of a DIY blister repair, the price is a drop in the bucket. The only thing that I'm a little nervous about it whether or not I'll be needing a second coat on any of the blisters.
My next step is to finish the remaining parts of the starboard hull, and begin sanding. I plan to knock down the initial layer with 80 grit paper on a 8" random orbit sander, then go back over it lightly with 120 grit to smooth everything out a bit more. Epoxyworks recommends wet sanding, however I am not interested in hand sanding this much surface area, so I'm going to carefully substitute a machine and deal with the mess.
Read Part II of this topic next. In it I describe observations made during the sanding of the repaired blisters.
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