40 E-Tec Prop

[photoman]

1) Performance issue you are trying to correct.
RPM to low - 4800

2) Current prop manufacturer, model, aluminum or stainless and as a minimum.
SS - second hand manufacturer/model not known

3) Current prop diameter and pitch (required).
17

4) Wide open throttle RPM and speed with an average load (very helpful)
4800 @ 30mph GPS

5) Engine/drive make, model, year, and HP
40 E-Tec 2007

6) Boat make model, year, length and weight
Southfork, 2007, 15', 800lbs?? 1200 loaded??

I bought this second hand. Motor has very few hours on it. Boat rated for 30hp. The prop is second hand and had been worked. Prop calculators would suggest that the prop is actually at 19 pitch. Motor is on a CMC PT-130 tilt and trim with a 6" setback. Motor is about 1" above the bottom of the boat.

Suggestions??? Lower pitch?? Raise Motor??

Thanks in advanvce.

 

[steelespike]

Re: 40 E-Tec Prop

Going seat of the pants I would say a 17" is typically what is run on boats similar to yours.rpm about 5,400.It would appear your prop is indeed closer to 19".
With that setup I would raise the motor till you get venting problems.After all it is free.

 

[hwsiii]

Re: 40 E-Tec Prop

Spike is right about moving the motor up first Photo and seeing what happens with your RPM, but my calculations show you need a 17" pitch prop to get to the proper RPM at this time. Theoretically you are showing a prop pitch of about 19" and a prop slip of about 7%. If you change to a 17" pitch prop in the same make and model with your present RPM you should have an increase of about 550 RPM.

Prop Change

H