Need some info about propellers

[Roger Sr]

I have a 15hp Johnson and would like to know what the difference in pitch as in 8-9-10 and so on mean. also what is the difference between 3&4 blades & when thay say standard rotation. what dose that mean. i know it sounds dumb. but I'm new to boating and would like to know these things. thanks for any help you can give. Roger.

 

[ob]

Re: Need some info about propellers

Props are designated by circular diameter in inches and pitch which is also designated in inches of theorectical forward distance travel per revolution. In other words if a prop is labeled 11X13 the 11 indicates that the prop has a circular diameter of 11 inches and a theoretical forward distance travel of 13 inches per one rotation.

Three or four blade props is just that.The prop is either of three or four blade design.Depending on the application need.

Lastly ,standard rotation is the most common application for most single engine outboard boats and simply means that the prop when viewed from the rear of engine rotates in a clockwise direction.Counter rotation turns counterclockwise when viewed from rear of engine. Many twin engine equipped boats will have one engine which is standard rotation and one that is counter rotation.This keeps on prop from robbing the other of water bite and helps prevent excessive torque steer.

 

[Roger Sr]

Re: Need some info about propellers

ok i got that.now what are the different applications for a three or four blade prop. dose one have more bite.or give more forward push? Roger.

 

[ob]

Re: Need some info about propellers

ok i got that.now what are the different applications for a three or four blade prop. dose one have more bite.or give more forward push? Roger.

Four blades are generally used in shallow running applications such as tunnel drive rigs ,but otherwise I'm not much of a prop guru.Might want to post this question in the propeller question forums.Some pretty hep guys can touch on this.

 

[Roger Sr]

Re: Need some info about propellers

Thanks for what you did tell me.it's more then i did know. Roger

 

[ob]

Re: Need some info about propellers

Glad I could help.

 

[Roger Sr]

Re: Need some info about propellers

does turning point make there hustler in ten inch. to fit my 93 15hp Johnson. i was looking at an ad for them. and would like to try one. if thay make it for this motor. Roger.

 

[Silvertip]

Re: Need some info about propellers

You will find four blade props in a number of applications ranging from work boats (boats that carry heavy loads), pontoons, some tournament style boats use them as well. Propeller design is more than diameter, pitch, and number of blades. There are stainless steel and aluminum props, props can have more or less rake which is the fore-aft angle of the blades. Blade shape and amount of cupping are also design considerations. What you should do is simply Google Marine Propeller Design or Marine Propeller Theory.

 

[jauguston]

Re: Need some info about propellers

If your Johnson is similar to my '92 Evinrude 15 the factory prop is a 9?X10 and works very well. I have mine on a Crestliner 1448 Jon boat and it will push it 25 mph at 7000 rpm. Great performance out of that little motor.

Jim

 

[Roger Sr]

Re: Need some info about propellers

If your Johnson is similar to my '92 Evinrude 15 the factory prop is a 9?X10 and works very well. I have mine on a Crestliner 1448 Jon boat and it will push it 25 mph at 7000 rpm. Great performance out of that little motor.

Jim

mine is on a 12ft Gregor.the factory prop is a 9.5x12.5 and it works very well also. but i have read about other props. and wanted to know what the difference was. like with three or four blades.and pitch .and so on. thanks Roger.