Jedibrad said...
agreed^^ strapless surfboard is the best for bad knees and ankles
Have to disagree with the surfboard idea. A large flat surface that doesn't penetrate the surface through the chop will belt the hell out of your knees. The only way you stay on a surfboard without straps is with very bent knees so you ride mostly crouched in chop at speed which works your legs like a skier doing moguls.
I suggest riding something like a Cardboards Tyro. Generous double concave and plenty of flex gives it a ride, (as a customer explained to me the other day), like a Cadillac.
Super smooth, no harshness at all and easy and fun to ride even in the worst chop (Pinnachop).

Cheers,
DM