I posted a recent project for a stern rail seat that I made for our P42. It worked fine for me, but when the admiral used it she leaned back causing the seat to unclip from the rail. No harm done, but it forced me to make a rail clamp to secure the seat to the rail.

Stern Rail Modification

I made the clamp from 1/4 SS rod. I cut threads on one end of the rod and bent the other end into the shape of a hook.

Seat Clamp

The threaded SS hook slides through the seat. I added a spacer that the hook also slides through so that when the seat is in place a wing nut takes up the hook slack until it is snug against the rail.

Clamp Function

The SS hook does the job. It holds the seat firmly in place, but yet it still allows the seat to rotate down if I want. The hook also locks the seat onto the life lines while not in use.

Holds The Seat Firmly

I tried out the modification and it seems to work as designed. A sea trial is still in order and tried by other parties to see whether there are any other design quirks. This should hold the seat secure to the rail.

Finished Product