Re: How to fasten down back to back and jump seats?
I glassed in supports directly to the uncarpeted, fiberglass deck on my 15' Yarcraft. used stainless steel t-nuts on the boards, screwed in the bolts, PL'ed the boards to the floor to seat them, then glassed the supports into the floor with mat and resin. When it all dried, I undid the bolts and ground off any excess glass on the nuts. Once painted (I painted the entire deck instead of using carpet) I drilled through the base on the seats and then ran the bolts through the seat supports into the t-nuts. It allowed me to take the seats off whenever I wanted which came in handy when I had to replace one of my seats a couple of years later. Just became a matter of drilling matching holes on the new seat base, and bolting in the new one.
Rgds