Kris--As you know I'm building a SwitzerCraft Baby Bullet from Germany and for racing they have a formula for the utility boats that somewhat duplicates what might be a scale like speed. Its called the yardstick Index. Yardstick index= specific engine speed(kV-value) x battery voltage (volts) x propeller diameter (mm) x propeller pitch (slope factor) . My question is about slope factor of my 42x55 ABC props. What would be their value? The maximum yardstick number is 1,370,000 for the class. I might have to use a different motor from the UL1 2030 kV or a smaller prop etc. All the information on this subject is available on the 152 vo web site at start > The 152vo racing class> The class rules > yardstick and setups. I'd be appreciative for your input as to what setup I should use (I'll probably try the lawless conversion lower unit or a OES. Thanks for your help--Anyone else on this forum--I'd appreciate input also. Ray Hamby
