Mercury Optimax 150 2011 boat not getting up to full rpm

the_dude

Seaman
Joined
Apr 13, 2014
Messages
51
1) Performance issue you are trying to correct.
Boat is only getting up to about 4500 rpm

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Aluminum, not sure of brand but it came from an evinrude motor. I have a Mercury. I also have an Evinrude Cyclone prop, but my shaft doesn't spin when I install it, so I guess that one won't work.

3) Current prop diameter and pitch (required).
14.8X17, I should note that it's an evinrude prop and I have a Mercury.

4) Wide open throttle RPM and speed with an average load (very helpful)
4500RPM is the highest I can get it to go right now. It should top out 1000RPM higher.
1200# total, maybe more= Average load is 80 Gallons of gas, 2 200# guys, and a 30Gallon bait tank

5) Engine/drive make, model, year, and HP
Mercury Optimax 150 2011

6) Boat make model, year, length and weight
Bayliner Trophy, 1989, 2103
 

the_dude

Seaman
Joined
Apr 13, 2014
Messages
51
1) Performance issue you are trying to correct.
Boat is only getting up to about 4500 rpm

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Aluminum, not sure of brand but it came from an evinrude motor. I have a Mercury. I also have an Evinrude Cyclone prop, but my shaft doesn't spin when I install it, so I guess that one won't work.

3) Current prop diameter and pitch (required).
14.8X17, I should note that it's an evinrude prop and I have a Mercury.

4) Wide open throttle RPM and speed with an average load (very helpful)
4500RPM is the highest I can get it to go right now. It should top out 1000RPM higher.
1200# total, maybe more= Average load is 80 Gallons of gas, 2 200# guys, and a 30Gallon bait tank

5) Engine/drive make, model, year, and HP
Mercury Optimax 150 2011

6) Boat make model, year, length and weight
Bayliner Trophy, 1989, 2103
I should mention I'm mainly concerned about low speed planning, and gas mileage. It's a fishing boat. The boat does 40mph the way it is now.
 

WesNewell

Chief Petty Officer
Joined
Jan 3, 2018
Messages
497
Mercury prop selector shows you being propped about right and getting about the right top speed. First I'd check the tach for proper setting. Check engine height. Check hull not dirty. Flotation not water saturated.Fuel flow and engine condition.
 

the_dude

Seaman
Joined
Apr 13, 2014
Messages
51
OK, thanks. I have a feeling that running the wrong brand might be the issue, can't get the locking nut on. Just ordered a 15x17 black max from amazon.
 

WesNewell

Chief Petty Officer
Joined
Jan 3, 2018
Messages
497
Brand of prop shouldn't matter that much at the same pitch. If I had to make a wag, I'd think your tach is set wrong since a 17p prop can't hit 40 mph at 4500 rpm with a 1.87GR, which I'm pretty sure is the gr of a 2011 150hp merc.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
All I can advise is sticking to mercury already incredible variety of props, on a equally superb engine like yours. Unless I’ve missed something over the years...there just isn’t better. Especially when propping a mercury engine.
 
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