How Propeller Pitch and Diameter Affect a Sportfishing Boat

Our engineers base propeller selection on a lot of factors including weight of the boat, desired speed, size of the engines, reduction gears, etc. Aspects of the propeller selection also include the blade area needed, which determines the number of blades and the maximum diameter able to fit under the boat. The propeller for the 46 Release Boatworks with twin 1000 hp engines is an ACME 5 Blade 30.5″ Diameter, 49.5″ pitch, with .105 cup. Cup is bending over the tip of the propeller blades in order to better spread the pressure to the trailing edge of the blade. Cup also allows for the pitch of the propeller to be lowered, while also raising the effective pitch.  

In case you were wondering how important choosing the correct prop is, here are a few basics on how different aspects such as pitch and diameter can affect your boat performance.

Propeller Pitch

Propeller pitch is the distance that a propeller would move in one revolution if it were moving through a soft solid, or the distance that a propeller would “drive forward” in each complete rotation without being attached to a boat. The distance your boat is propelled forward with one rotation is actually less than pitch, and the difference between these two numbers is called “slip”

Basically, the lower your propeller pitch, the better your “hole-shot”, but you also sacrifice top-speed by causing your engine to reach maximum rpm at slower speeds. On the flip side, a higher pitch affects your boat performance by delivering greater top speeds, but at the expense of your acceleration or hole-shot.

Propeller Diameter

The measurement from the tip of one blade straight across to the tip of the opposite blade is the diameter. You can also multiply the radius (the distance from the center of the hub to the outside of any blade) by two.

Basically, the higher the propeller diameter, the higher the efficiency with an exponential increase in thrust and torque. However, too large of a diameter can also equate to high drag.

If you’d like more information about Release Boatworks custom builds, please call 833-FISH-RBW or email

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