What is diameter? Propeller diameter is distance across the imaginary circle that a spinning propeller makes. It can be easily determined by measuring the distance from the center of the hub to the tip of one of the blades and multiplying that number by 2. Diameters between different propeller manufacturers may vary slightly.

For example for a V6 outboard application, Turning Point uses a 14-1/4" diameter where a different manufacturer may use a 14-1/2" diameter. This small variance does not affect your performance as much as the pitch and overall design.
However, larger diameter propellers - 15" or 16" diameter - are designed for larger boat applications - 23 ft +, and are not ideal for 15" - 22" foot run-a-bouts. These larger boats need more blade area to push more water.

What is rake? Propeller rake is the degree that a propeller blade is angled in relation to the hub. Props with higher rake typically have better speeds and greater lift. The better performing propellers typically have between 20 - 30 degree rake angles.