I purchased this 1.5 inch seat for my kayak (SOT that did not have a seat at all).  It stayed in place just fine on a 2 hour paddle and my rear end and legs felt much better.  However, because it elevated me so much, it interfered with the position of the seat so that I no longer had appropriate back support while paddling. I think I should have purchased the 1" one.  Anyway, it got wet during my paddling and the water just beaded off when I got out of the kayak and dried completely within minutes.  If you are looking for a cheap, comfortable kayak seat I would recommend this one as long as you get the correct amount of cushioning in inches.