Video Transcript: Hi, I'm Tom with Solas Propellers and I want to give you a few tips on how to choose the right propeller to maximize your boat performance. By selecting the right propeller, your engine will perform in the designed RPM range at wide open throttle.
A propeller is defined by its diameter and pitch, which are both measured in inches. Let's say you have a 15 x 20 propeller. Diameter, the first number, measures the distance across a circle made by the blade tips and in this case would be 15 inches. Diameter increases as you go down in pitch and decreases as you go up in pitch. Pitch, the second number, is the distance the propeller will travel in inches through a solid medium in one rotation. In this case, a propeller with a pitch of 20 will theoretically move 20 inches per rotation, assuming there is no slippage.
The lower the pitch, the better the acceleration or hole-shot you will have, with lower top speed. The lower pitch lets the engine reach maximum RPM at slower speeds.
On the other hand, a higher pitch will have better top speed, but slower acceleration and hole shot. Remember that each inch of pitch is worth about 150 to 200 RPMs and increasing the pitch will decrease the RPMs and vice versa.
In order to choose the correct diameter and pitch of the propeller, you'll need to know the manufacturer's RPM range. Operating in the middle to upper RPM range allows for some flexibility when the boat may be heavier or lighter due to the load.
So, the main points to remember are: if you're looking to gain hole-shot or increase your RPMs, decrease your pitch; if you're looking to gain top speed or lower RPMs, increase your pitch and always operate within the manufacturers recommended RPM range.
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