I picked up approximately .75 to 1 full knot sailing speed with a Max Prop on a Tayana 37. Had a fixed 3 blade 18" dia.
Best advantage is that you can alter the pitch (underwater adjustmant is a pain) to optimize the rpm / horsepower ouput of the engine.
I thought the Auto Prop. was well overpriced and therefore I went to the Max. Another possibility is a feathering prop from Martec - the Martec couldn''t fit my aperture, ... was the most economical available.