Swivel seat base suggestions needed

I’ve got an old boat with wooden bench seats. I want to mount swiveling seats to two of the benches. My requirements are that they swivel easily and can be easily removed. Anyone have any suggestions on a combo seat mount and base that would work without a post? I’ve seen a few seat bases that just have a 3/4 inch pin on the bottom, and I’ve seen floor mount bases that I could mount on my wooden bench seat with a 3/4 inch hole, but have heard many are very loose causing the seat to rock, and others lock in so tight you can never get them out. Anyone have experience with any that work “just right”…..

There are bases that free swivel and some that swivel when the lever arm is pulled. Do you have a preference?

I have benches in my duck boat and added swiveling seats to both. They clam around the bench. 5 minutes in and out. It’s basically big u holster that clamps under the bench

Thanks for the responses Dave and Bearcat. I prefer a free swivel type. A clamp on style will not work since the side of my bench seats come straight up and are even with the outer edge of thee top. There is nowhere for the clamp to hold. I also don’t like how stiff those swivel bases are. I was hoping for a pin-in-hole type solution for free spinning.

My front one is 2 runners that the square base slides in and out. So everything is mounted to the top of the bench its self.
I can send pictures after work if interested. Its basically 2 aluminum channels the seat base will slide in and slide out.

I mounted my seat and swivel to a piece of plywood that is longer than the seat is wider. Then just screwed it down to the boat seat.