I attach a knife with paracord and a short Velcro strip to the shoulder strap. The paracord goes around the shoulder strap and through the top loop on the scabbard, the Velcroe secures the bottom part of the knife (through the slot on the scabbard adn around the PFD strap). Not very pretty but very secure.
Aquaseal is pretty good stuff… as long as it’s not a silicon sealed fabric, that stuff should stick. Make sure to wash everything thoroughly before gluing. We use 90% or greater isopropyl alcohol.
Thanks for the help folks. I ended up sewing it. This was a bit tedious but not too hard. I pre-punched (actually drilled) holes along the edge of the lash tab. I then hand stitched the edges but with enough slack to allow me to move the tab around so I could access all the holes and get the (straight) needle in and out of the PFD shell fabric.
Once I was done with that, I worked all the slack out of the thread and finished it off. I’ll have to see about using aquaseal if things seems to get loose, but it’s fairly solid.