I purchased a used sun dolphin sportsman. It came with seats that are different than the one it comes with. I bought seat supports, and used a nut and bolt to attach the seat swivel to the seat supports. The problem is a lot of the time I feel like I will fall backward if I lean back. Is it like that for the stock seats? Also, if I buy the stock swivel, how do you attach that to the seat supports and the swivel to a new seat? Thanks. Seat I'm looking at-  http://www.academy.com/shop/pdp/marine-raider-molded-bucket-seat#repChildCatid=10821

swivel is # 5.   http://www.sundolphinboats.com/partspage/partdtl/kl8.html

check out the pelican bass raider thread on here...over 100 pages. I bet you find your answer in there.     It might just be the type or style of seat.