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Kennneee

Fuel Consumption/Propellers

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Hi Guys- I would love to know what kind of fuel consumption you are seeing with your Bluejackets. Have you played with different propellers and what kind of changes have you seen in your fuel burn and performance? Three blade vs. four blade? 

Ken

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Is your engine hooked up to a chart plotter, that will give some info about the fuel consumption.  Mine does tell the "Miles per Gallon"  and it doesn't seem to make much difference throughout the speed range.  I would have thought going slow would give a better mileage.  About 3.5 mpg.

I know little about propellers, just that they need to be sized to get the rated engine rpms at full throttle.  Larger diameter gives more pushing power, greater pitch more speed.  I had to go back in pitch a bit to get the rated rpms.  Just kept the original propeller as a spare.

I would like to know what the difference is between 3 or 4 blades.

I am building a push boat for a Chesapeake Skipjack at the Reedville Fishermen's Museum .  Hopefully through that I can find out what a 4 blade vs. a 3 blade does.  But that will be a while.

Your boat just looks astonishing and you should be proud of it.

 

Egbert

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14 hours ago, ejds said:

Egbert- I am waiting to receive the NEMA 2000 cabling I need to hook the motor up to my chart plotter. It will probably be a couple of weeks since it is coming from the US and things can be slow getting here. I did fill my fuel tank and checked the consumption the old fashioned way by doing the math. So far she is getting just under 5mpg. That said, like many young things, she will never be lighter. No water and other junk aboard yet. On the other side of the coin, I am still playing with getting her properly propped. My first prop was a 13.5x16- 3 blade and I couldn't get the engine to rev higher than 5200RPM . Redline is 6000rpm. I have have a 13.5x14 on her now and still can't get the RPM above 5600RPM which might be ok. I don't expect to be cruising at the 26 -27 knot speed I am at WOT. I have been advised to try a Solas Amita 4 blade which I will probably do. Still much to learn.

She seems to get up on plane effortlessly and her nose points up around 3.5 degrees (digital tiltbox). I find very little difference in speed and bow angle when changing engine tilt. I run the engine is almost all the way in most of the time. I wonder if that will change as she gains weight and sits lower in the water. I will let you know how the 4 blade prop works when I get one.

Thanks for the compliment. I just followed the directions on the back of the box:).

Cheers,

Ken

 

 

Is your engine hooked up to a chart plotter, that will give some info about the fuel consumption.  Mine does tell the "Miles per Gallon"  and it doesn't seem to make much difference throughout the speed range.  I would have thought going slow would give a better mileage.  About 3.5 mpg.

I know little about propellers, just that they need to be sized to get the rated engine rpms at full throttle.  Larger diameter gives more pushing power, greater pitch more speed.  I had to go back in pitch a bit to get the rated rpms.  Just kept the original propeller as a spare.

I would like to know what the difference is between 3 or 4 blades.

I am building a push boat for a Chesapeake Skipjack at the Reedville Fishermen's Museum .  Hopefully through that I can find out what a 4 blade vs. a 3 blade does.  But that will be a while.

Your boat just looks astonishing and you should be proud of it.

 

Egbert

 

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