For security on my Guillemot Coastal, I made my bow grab loop out of 1/8" stainless cable, with a nicopress fitting. The whole thing is covered with a white plastic protective sleeve (easier on the fingers), with rigging tape around the nicopress fitting. I can then pass a cable lock through the grab loop and lock the yak to anything convenient and permanent looking.

At least this means the thief will have to come prepared with bolt cutters or heavy duty cable cutters. As someone else said -- it will keep an honest person honest.