Commonly known as the 'Hurricane Backrest Upgrade', you can add an Airstream seat back to most kayaks to improve the ergonomics. This setup will greatly increase your back support as well as adding comfort and control to your kayak.
The Airstream seat back is height adjustable, giving you the option to set it low for when you are paddling and then in a higher position when you stop to fish and want more back support. It won't absorb any water, as it is made from fabrics that do not hold water.
Installation is easy, although you do need to drill a couple of holes in the kayak to attach the base bracket bracket.