Jay Martin
August 20th, 2011, 11:35 AM
Here's one of the biggest problems I see people run into when selecting a propeller for a boat.
Lets say I have 20 foot XYZ boat with a 225 xyz motor, lets say I'm running a 27 pitch large hub propeller and want to make the switch to a 4 blade propeller (most 4 blades are O-T OR over through exhaust), what alot of people don't know is you will have to drop one pitch when going to the 4 blade, this means a 26 pitch will now be what the boat needs to keep the rpm's the same or close to what the 3 blade was running.
Now! Lets say I wanted to go for a HIGH Performance prop like the Mazo R.E. series or a Mercory Chopper, If I'm running the 27 and make a switch to the over hub style then I would have to increase the pitch by 2, meaning now I would need a 29 pitch.
With the overhub style there is more exhaust flowing through the blades thus increasing slip, so more pitch is required.
When going to a 4 blade from a 3 blade you simply have more blade area which results in more bit meaning less pitch (1) is required.
Of course there is a fine line when it comes to prop diameter, I will talk about that in a later post.
Jay
Lets say I have 20 foot XYZ boat with a 225 xyz motor, lets say I'm running a 27 pitch large hub propeller and want to make the switch to a 4 blade propeller (most 4 blades are O-T OR over through exhaust), what alot of people don't know is you will have to drop one pitch when going to the 4 blade, this means a 26 pitch will now be what the boat needs to keep the rpm's the same or close to what the 3 blade was running.
Now! Lets say I wanted to go for a HIGH Performance prop like the Mazo R.E. series or a Mercory Chopper, If I'm running the 27 and make a switch to the over hub style then I would have to increase the pitch by 2, meaning now I would need a 29 pitch.
With the overhub style there is more exhaust flowing through the blades thus increasing slip, so more pitch is required.
When going to a 4 blade from a 3 blade you simply have more blade area which results in more bit meaning less pitch (1) is required.
Of course there is a fine line when it comes to prop diameter, I will talk about that in a later post.
Jay