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View Full Version : Propellers, Educate me, Please?



xedmoc
07-07-2010, 10:34 AM
What is the effect on propulsion when the size of a propeller is increased or decreased? Also, what is the effect on the same with an increase or decrease in pitch on a prop? In addition, what does the "+" mean?
Here's my prop history -
14.5" x 17 michigan wheel painted aluminum (on boat now)
14.25" x 21 + viper for omc cobra ss (now gone)
14.75" x 21 viper for omc cobra ss (now gone)
15.25" x 19 mercury mirage (ordered)
13.75" x 21 mercury vengeance (on production donzi 16 classics, recomended by Donzi Corp)
Also, how does your outdrive upper gearset ratio affect propulsion, as a factor of prop size and pitch - Looking for general rules here.
Help me understand and I will reward you with cigars. Just PM me your addy, and a package will arrive soon.
Kind Regards,
Eric

mrfixxall
07-07-2010, 10:47 AM
What is the effect on propulsion when the size of a propeller is increased or decreased? Also, what is the effect on the same with an increase or decrease in pitch on a prop? In addition, what does the "+" mean?
Here's my prop history -
14.5" x 17 michigan wheel painted aluminum (on boat now)
14.25" x 21 + viper for omc cobra ss (now gone)
14.75" x 21 viper for omc cobra ss (now gone)
15.25" x 19 mercury mirage (ordered)
13.75" x 21 mercury vengeance (on production donzi 16 classics, recomended by Donzi Corp)
Also, how does your outdrive upper gearset ratio affect propulsion, as a factor of prop size and pitch - Looking for general rules here.
Help me understand and I will reward you with cigars. Just PM me your addy, and a package will arrive soon.
Kind Regards,
Eric


a bigger diameter prop will give you more pulling power and more stabilty(a wider propeller thrust) a smaller diameter will narrow down the thrust and throw the water out the back of the boat further which in return will give you more speed but less stabilty..

+ means on a mirage sryle prop,,that prop has more of a rake,longer blade area..a regular mirage has shorter blades

gear size,,with a higher the gear ratio you will be able to spin a higher pitch prop..if you havew a 2.0 ratio the engine will spin 2 times faster then the prop

xedmoc
07-07-2010, 02:48 PM
Thank-You, That is very interesting and helpful. Will PM you now too.

E