Did I go the right way with my prop guess

Wicked Good

Recruit
Joined
Apr 10, 2008
Messages
2
Right now I'm running a 15x17 3 blade on my Trophy. I have the 3.0 alpha 1 w/gear ratio of 2:1. My max rpm is 4400 to 4800.

With this prop at WOT I hit 4400 @ 31mph.

I want to got to a 4 blade prop for a better hole shot and bite seas when entering my harbor. Soooo...

I have on order, a 15x16 4 blade. I figured the decrease in pitch would raise my RPM 200-300 and going to the 4 blade would decrease it by 100-200 making it close to a wash in the RPM changes and keeping me in the engine manufactures recommended range.

All this figuring comes about by reading A LOT about this topic.

Does my logic hold true and do I have a good chance of getting the desired results or is it always going to be "don't know until you try it" scenario.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Did I go the right way with my prop guess

Some suggest staying the same pitch some say drop 1-inch. I personally think you went the right way but you do need to understand the prop design has a lot to do with performance so a changing pitch and changing prop manufacturers means you are also changing design characteristics. Therefore a prop change like that is a crap-shoot.
 

Wicked Good

Recruit
Joined
Apr 10, 2008
Messages
2
Re: Did I go the right way with my prop guess

Alrighty then, we'll see what happens end of the month. I'll try it out then.

Thanks.

BTW: Going from a Mercury Black Max 3 blade to a Michigan Wheel Vortex 4 blade.
 
Last edited:

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Did I go the right way with my prop guess

Check your current prop carefully for a part number. Some are hidden under the prop nut and washer. Post the number and perhaps we can identify the manufacturer.
 
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