Hello: I just became a member and have never posted anything before so if I make a mistake, I apoligize. Last year I bought the socorro. A 26' Blackman billfisher with a kad 32 4cyl. diesel engine. The boat is fantastic, It's everything I hoped it would be and more. I'm running a A-5 prop. Max throttle is 4000 rpm. I drop the rpm,s down to 3400rpm, full tank of fuel,bait tank w/bait, three passengers plus gear, I'm running about 18knots on calm water. I want to buy a spare prop. I've been reading about the A-4 prop and what I.ve been reading is that the A-4 is the prop of choice. If anyone has a opinion for or againest the A-4 versus the A-5, I would greatly appreciate your advice Thank you Jack pinto