36.) Everything is Different, the Second Time Around

Now that's what a proper vacuum bag is supposed to look like. Hooray!

I bravely (or stupidly) attached six planks again this time. But to help slow things down and allow me to be more careful I used West System's extra slow epoxy hardener instead of just the normal slow hardener. The extra slow stuff is made for boatyards in tropical climates, but lately that's just the sort of weather we've been having in New York. It provides a substantially longer "pot life" (when the epoxy is thick in the mixing cup) and takes 24 hours to cure at a constant 72 degrees.

The most important thing I did better this time, basic as it is, was to keep my plank marking system simple so I didn't accidentally apply any epoxy on the wrong side of the planks like last time.  

I also was much more careful with all the materials and about establishing a good seal around the area to be vacuum-bagged. The photos below show the tape and the way it goes on (the fourth side is hidden on the outside of the boat). I still had a few tiny leaks (which is all it takes to mess up a vacuum), but they were fairly easy to plug.

The super slow epoxy also gave ample time to line up the planks properly and staple them down. I still found it impossible to get them absolutely perfect, with no gap at all, but I came pretty close. I am guessing I will have figured out how to do it just right by the time I install the last plank (which of course will tempt me to pull them all out and start all over again—an urge I hope to vigorously resist). Stapling was all that was used to hold the planks together for gluing when the boat was first built.

I am not going to show all of the steps involved with shaping and vacuum bagging in this post because I have to repeat the process four to six more times (depending on how brave I get) to finish the hull. That will give me more opportunity to explain this process in greater detail. I also wanted to focus on avoiding a repeat vacuum bag disaster, so I also left the iPhone on the sidelines for this go around.

The vacuum pump is still running in the shop as I write this. It will need to stay on for at least 24 hours to maintain the seal that is clamping the new planks to the hull. That's much longer than it would usually take using a faster hardener. The risk is that if a leak develops during that time, the vacuum could lose some or all of its pressure and ruin the job.

One thing I am going to do differently in the future is to get a proper suction valve to attach the vacuum hose to the bag. The way I am doing it (with multiple holes cut in the end of the hose that's inside the bag) works okay, but it's hard to get a perfect seal around the place where the hose enters the bag.