looking for a better prop for my yamaha 300

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GoodChance

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I had a 17" ECO on a 2300 DVCC with a F300. With a normal load I was at 6100rom (and possibly hitting the rev limiter.... not sure). In short, 17" wasn't enough prop. So I got an 18" ECO from Ken at Prop Gods. Max RPM went to 5800-5850 (perfect) and my speed and fuel economy both improved.

By far, the ECO is the best prop on the 23 DV hull.
 

Swatski

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One thing to keep in mind is that all those displayed mpg numbers are calculated rather than measured, and higher pitch props generally tend to show better mpg numbers (as compared to actual fuel burn rate - empirically calculated to get the real numbers).
Hardly practical to do with different props, but it’s the only way to really know.
 

GoodChance

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One thing to keep in mind is that all those displayed mpg numbers are calculated rather than measured, and higher pitch props generally tend to show better mpg numbers (as compared to actual fuel burn rate - empirically calculated to get the real numbers).
Hardly practical to do with different props, but it’s the only way to really know.
Not sure I'm following your logic or even what you are trying to state.

Yes...... higher pitched props GENERALLY get better mpg (fuel economy) assuming that the boat/motor combination is still reaching the recommended WOT rpm of the manufacturer. For example, a 18" prop at 5800 rpm (WOT) but cruising at 4000 rpm will GENERALLY get better mpg than a 17" prop on the same boat with a WOT of 6000rpm yet cruising at 40000 (or even 4200).

You are correct in that a boat that is OVER-PROPed and can not reach the max. recommended WOT will be lugging at cruise speed and fuel economy will suffer. Same is true for a motor that is mounted too low (but that's a different topic)
 

Swatski

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Yes...... higher pitched props GENERALLY get better mpg (fuel economy)
How do you know that?
Did you measure it, or did you read it off of the command link (as calculated by the ECU)?

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Swatski

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Not sure I'm following your logic or even what you are trying to state.
Not to be redundant but, since you asked, the point I'm making is - fuel burn rates calculated by the onboard gauge are a theoretical display, based on an algorithm built in an ECU, with proprietary logic. Those calculations maybe generally close to the actual (measured) burn rate. Until you start pushing the system - and then all bets are off.

You either measure it, if you really want to know, or it is just a guesstimate.

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GoodChance

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How do you know that?
Did you measure it, or did you read it off of the command link (as calculated by the ECU)?

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Calculated by the Yamaha Commandlink and calculated by the Raymarine MFD which is connected to the ECU on the motor. Both systems have been field-verified to be 99.x% accurate (based upon multiple fuel tank refills of known volumes vs estimated depletion).

Common-man ...... I'm a numbers guy. Ain't my first rodeo
 

jzumi

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Why not go to the pro's and get expert advice? Call Prop Gods. Have your current performance numbers available.
 

Swatski

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Calculated by the Yamaha Commandlink and calculated by the Raymarine MFD which is connected to the ECU on the motor. Both systems have been field-verified to be 99.x% accurate (based upon multiple fuel tank refills of known volumes vs estimated depletion).

Common-man ...... I'm a numbers guy. Ain't my first rodeo
I appreciate your work and information sharing, it is crazy hard to get these kinds of data in boating.

Your posts are informative, and I'm most interested in the overall "feel" with those different impellers, your descriptions being very helpful - coming from first hand experience.

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