arcdude

Hi Don, The first number is the diameter of the prop and the second number is your pitch so the 5x4 is smaller in diameter yet the same pitch. Usually the rule of thumb is if you go down a size in diameter you can go up one increment in pitch. By increasing the pitch it will have less pull at the bottom end and higher speed at the top end and vice versa the other way around. From your previous post in having to boat in algae I would suggest the higher torque the bottom end will give you rather than the top end speed to get you through the gook a little easier. I'm no expert so just offering my experience which is usually following the manufactures recommended prop for the applicable motor and electrics are quite sensitive to heat so any changes will likely have a negative effect on the motor. All you have to remember is high pitch = high speed, low pitch = torque, Cheers