Everybody
Sheet tension is an idea i hadn't considered but will certainly give more thought, could be improved without much effort. Boom vang on a dinghy does wonderful things.
Interesting comments about sail material. I am confident that the main is suitable for the job as it is not that old, the jib may be a bit under so could be stretching as it is loaded up, maybe a bit full for a cat as well.
The mast base is is set up to allow rake adjustment but nothing sideways so i'm sure it is getting loaded up in all sorts of odd ways. I'm sure i have seen some deformation whist sailing