Blister Repairs III - Still Going

Another long day of sanding, although I have definitely continued to improve my technique.  First of all, I have switched to using my nice Porter Cable 5" random orbit sander.  No more screwing around with that little palm sander.  Second, I'm now using 80 grit paper rather than 100 grit.  Big, big, big, difference!  I may even be able to use 60 grit to knock down the epoxy then hit them with 80 for a shorter duration.  But the bottom line is that I'm now making solid progress on the fairing.

My experiment in skipping the spreader and just building up the Six/10 was partially successful.  The blister are definitely more filled than when I used a spreader, but in many cases they still need a subtle touch up to become truly fair.  Less touch up than the holes where I used a spreader, but I'm not going to be able to get away without two coats.  The good news is that by not spreading the epoxy to surround the blister I'm saving a lot of time.  There may be a way to do this with a spreader, but I didn't find it.

I have about another  three hours of sanding to go at this pace, then a re-coat, then probably a day of sanding.  I have removed so much bottom paint at this point that I may just sand down what little remains and throw down a new layer of barrier coat to even everything up.  Not sure yet...  For now I'm just pleased to have made some solid progress.

Fast Blister Repair Using West Six/10 Epoxy

I finally got around to trying out the new 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.

Fairing Compound and the Evil Tarp Monster

After a long morning of filling blisters I began fairing the side decks with a mixture of West 105/206 and 407 low density fairing compound.  I chose the 407 over 410 because it's made to be stronger, and the decks take some abuse.  Using a large spreader I worked the compound into place.

It's very messy stuff to work with when you're not yet an expert because you need to apply it over large areas with a wide spreader.  In my case, the work was made more difficult because it was insanely windy this afternoon.  Not only were the gusts driving me nuts as I worked on the narrow side decks without lifelines, but every now and then it was blowing thin whisps of compound off the spreader and onto my decks.  Messy!
   

407 filer is unbelievably fine grained.  It actually flows like water as you stir it into the resin, and if you stir too quickly it will float into the air in puffs.  I ended up finding a rhythm using four pumps of the epoxy then filling it to somewhere between ketchup and peanut butter consistency.  It was hard for me to get it applied and smoothed out fast enough to work with significantly more pumps.  Not as efficient as possible, but it worked out fine becuase I keep a good stock of mixing containers, spreaders, and sticks.


Eventually I was able to get an initial coat onto 100% of the starboard deck, and 75% of the port deck. I ran out of time before I could finish the last short segment, so that's for next visit.  The picture isn't a very good one, but it gives the idea.

By the time I finished I had a very smooth surface a little thinner than what I'd need, but about 90% of what I expect it to be.  It looked fantastic to see a solid color and solid surface after all these months of jagged fiberglass.

Unfortunately, I had stretched the clock (as usual) and really needed to get the boat tarped up so I could make it home for dinner.  There isn't a lot of time between the end of school and my son's bed time, so I didn't want to miss more than necessary.  As I begin the next phase of the story, keep in mind my earlier statement about the wind conditions...

As I began wrestling the tarp from the bow back towards the stern the wind of course picked up.  It filled the tarp like a baloon.  I was holding on, but it took quite a bit of effort to keep the tarp from sailing away along with me.  As I worked it over the stern rail a gust slapped the big blue monster and caused it on both sides to snap in and out of the fairing compound a few times.  I was nauseated at the sight.

The good news is that this is the first coat.  I will need to sand it, and a few ridges or dents will be easily remedied by the second coat.  What I'm so, so, so not happy about is the tarp picking up fairing compound and no doubt spreading it on my tposides, and eventually ending with the condition of my tarp being epoxied to my hull.  I'm sure it will pull away easily since the tarp is so worn out, but I expect to have to sand the hull in a few spots to get rid of the mess.  Not what I had in mind, but with the windows out I absolutely HAVE to keep the tarp on the boat.

I'm dreading my next trip out, but maybe I'll get lucky.