Would a different prop make much difference????

[mjlyn]

Hi,

I have a 20 Lowe pontoon with a Mercury 4 stroke 60. My max RPM at WOT is 5400 with one person and fuel on board. Max speed is 16-17 by GPS. According to the Mercury website the max rpm range on the motor is 5500-6000.

I'm not sure exactly what size the prop is, but there is a long number ending with 11P n the prop. So i assume the pitch is 11. Do you guys thing a lower pitch prop would make any difference? I know it would increase the RPM, but would it change the top speed any? Also with say 6 people on board my max rpms are about 4500. Would the lower pitch help me out in that situation?

I'd like to be able to try a different prop, but i'm not sure if the dealers here will allow that.

Thanks in advance for any comments.

[dockholiday]

Was thinking the 4 stokes rpm was around 5400, and you may have been looking at the opti, but 5500-6000 is what mercs site says.
Might be able to get one or two miles per hr, but don't think it is worth the time effort or money. Probably would need a gps to see the difference. For example I first ran a17p and my max was 5300rpm with a 150hp and got 38mph so I dropped down to a 15p. It ran 5800 at 40mph. You may even get less than 2 mph difference.
doc

[mjlyn]

Thanks for the comment.

On the prop i have now some of the black paint has flaked off some of the surfaces. What has flaked off seems a bit thicker than just paint but it may be. Does that make much difference in performance? And what does a "cupped" prop do?

[HandymanHerb]

Cup helps in dig in and not blow out due to the weight your getting to move, you need to figure out how your going to use it at what load and prop it for that load.

You get around 200 RPM more per pitch number down.