I use one I got from Tacklewarehouse (where they are also on sale and cheaper) on my 16.5' tracker. I have the smaller one and it works fine. Buy a small diameter rope for a tag line too. You attach the tag line to the end of the sock so that dumping the water out is easier. Plus, I recommend attaching a float to the main rope in case your boat partner tosses it out without the rope attached (I'm speaking from experience on that one). 45 minutes later after dredging what seemed like an acre of water we got it back.
I fish from a square back canoe mostly and I have thought of getting one of these myself. My question about them is how do weeds effect them? I fish mostly shallow weedy spots or spots with no more than 2ft of water over the weeds.
Does the drift sock ever get in the way at all of reeling in fish, in anyone's experience?