I'm trying to find some "blind nuts" or "rivet nuts" for mounting a new trolling motor to my boat. The current motor uses these nuts - you drill a hole larger than you need, drop the nut in the hole and it expands outward as you tighten them, securing themselves in place the first time you cinch them down. I don't have access to the underside of the deck to put the nuts on the bolts supplied with the motor, so this seems to be the only solution. In the airplane world, they're called "rivet nuts" and are expensive and require an even more ridiculously expensive tool to install. If anyone can point me to the gizmos I'm looking for, I'd appreciate it!