I had the misfortune of getting trapped under a boat this summer and believe me, it is scary. We capsized a Hobie 16 and it was not very catastrophic. The skipper stayed on the top hull and I let myself down easily by stepping on the boom and then sliding into the water. I was at the front beam when the boat went turtle and the jib car cought the back top of my life jacket right behind my head. It took me under and all I could get out was "I'm hooked" and that was it. I barely got a gulp of air because it happened so fast. I was in a panic and I don't think I had the air or calm to be able to get a knife or untie anything if I had to. Luckilly, the skipper was close to me and pushed me down to get me unhooked from the car. I was struggling so much to get up when I really needed to just push away from the boat. I just didn't expect to be in that situation. It was only a couple of seconds, but it seemed like a VERY long time.

It seriously put some fear in me.

In my case, I was wearing a kayak lifejacket that zipped on the side, so you had to put your head through the top. At the time, I started to struggle to take it off, but it would have been very difficult. I switched to a kayak jacket that zips up the front and is easier to get in and out of. I know a life jacket is a life saver and should be kept on, but in this case, it could have killed me.

I think that you should add to your safety check list something about quick release gear in general. I am amazed at the people I see that have something around their neck by a lanyard like a GPS or cat key.