Prop Replacement: The Basic Ins and Outs

Prop Replacement: The Basic Ins and Outs

Propeller Selection Tips
Whether it's the tiniest outboard or a huge sterndrive, one thing they both have in common is that little prop in the water. Your propeller while small, plays a huge role in how your boat drives. Which is why regularly inspecting your propellers for damage is vital. All the horsepower in the world won't help a boat move any easier if the propeller is damaged.

When it's time to replace your propeller, keep these propeller selection tips in mind to help you make the correct choice.

Wide Open Throttle (WOT) Range:

The first thing to do when replacing a propeller is to crack open that owners manual and find out the wide open throttle range. This will allow for the choice in propeller size. Which in turn translates to horsepower depending on the RPM of the engine at any given time. Remember to always shoot for the minimum RPM, which will allow you to gain the most horsepower from the engine at the same time.


Choosing the size of the blade is simple once the WOT range has been established. However, there are two important factors to remember. The diameter of the prop is figured at twice the length from the center of the propeller to the outer edge of the blade. The pitch, the second factor to consider, is defined as the forward movement of the boat's prop through one complete revolution measured in inches. For example, if you lower the prop's pitch, you can increase pulling power and acceleration. While on the other hand, a higher pitch prop can make the boat go faster, as long as the engine can keep up, so make sure your boat produces enough power to run a higher pitch prop.


Nowadays some props have a cup that is utilized in tandem to the prop blade. This greatly helps in cutting down on ventilation, thus giving the blades less of a surface area to gain more traction. Plus, cupped boat props promote efficient fuel consumption, and who doesn't like that!?This nifty little piece of curved metal also avails the prop to maintain performance at a higher trim and in tight corners, making this addition one to seriously consider adding.


Once everything is properly measured, the next step is to decide on what sort of material you are looking for in a blade. Generally, this is a choice between aluminum and stainless steel. Aluminum blades usually run more economically priced. However, the trade off being the greater likelihood of needing to replace in a shorter period, while the stainless steel offers comfort in its durability and longevity.

New York Marine Trades Association