The KAPE Seat is an option for sailors who require more trunk support. The side supports are adjustable in height and width.
The price is $800 for the complete seat with headrest- $600 if you would like to scrap an existing seat and just mount the new back on it. However it is better to go with a complete new seat as the old seat hinges are fragile and if you need to replace that anyways you're better off with a full replacement.
Read this testimonial from Kevin Penny from Halifax, NS:
"I've been a competitive racer in the Martin 16 since 2007 and purchased the KAPE seat in the summer of 2015 for my own personal Martin 16. I am a C4 quadriplegic (complete injury) and use the sip and puff system to control the boat. Because of my severe scoliosis, I always had difficulties getting comfortable in the boat and it affected my performance and comfort. Since having the KAPE seat not only has my comfort improved, I have more endurance on the water. The adaptability of the KAPE is the biggest advantage as I have been able to share my seat with individuals in our Able Sail program. As I tell everyone, a comfortable Martin 16 sailor is a better Martin 16 sailor!"