I am I over thinking the load readings

Spark600

Well-Known Member
Dec 28, 2013
460
South Shore Long Island NY
Boat Info
2015 Sundancer 410
Onan Generator
Mercury dinghy
Engines
Cummins QSB HO 380 HP
Zeus Pods
2015 QSB 6.7 HO
I seem to be using more fuel in the starboard motor then the port, About 6 gals at fill up
All readings seem to be in acceptable range except for the load readings were there is a 3 % difference, Should this be the same or is it acceptable.
I did have the props reconditioned in the beginning of the season.
Am I looking in to this to much or should I be looking for something.
How critical is it that both motors have the same load.
 

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Which side does the GenSet draw fuel from? That would make a 6gal difference
 
Another boat on our dock (Carver) was seeing fuel use differential and ultimately found out that the rudders were not correctly aligned. Odd as it sounds it fixed their slight load and fuel differences when they aligned the rudders to the Carver requirement. Their boat had Cummins.
 
I was just trying to figure out the same thing. What I found was when I had my tabs exactly the same I burned .7 gal/hr different. I also noticed my boat leaned to the port side. I always ran with auto trim on so didn’t pay much attention. Now I use auto to get up on plane then switch to manual and make a small adjustment to the tabs to even out and I burn exact same fuel/hr now. So try to adjust your trim tabs once on plane and see if that makes the difference for you too.
 
Another boat on our dock (Carver) was seeing fuel use differential and ultimately found out that the rudders were not correctly aligned. Odd as it sounds it fixed their slight load and fuel differences when they aligned the rudders to the Carver requirement. Their boat had Cummins.
The boat has pods so there is nothing to adjust, But thanks
 
I was just trying to figure out the same thing. What I found was when I had my tabs exactly the same I burned .7 gal/hr different. I also noticed my boat leaned to the port side. I always ran with auto trim on so didn’t pay much attention. Now I use auto to get up on plane then switch to manual and make a small adjustment to the tabs to even out and I burn exact same fuel/hr now. So try to adjust your trim tabs once on plane and see if that makes the difference for you too.
I have tabs on the pods as well as the boat.
Boat has auto glide tabs these work with the GPS data, motor data to give the boat optimum performance and fuel burn.
When I start to go I have the tabs on the pods in auto and the auto glide tabs in auto, once I plane off I turn the pod tabs off and leave the auto glide tabs in auto.
 
I had an 05 420 DA with Cummins 480CE's a few years ago with readings off like yours. After going through the aftercoolers, props, airseps and all fuel filters there was still a difference in readings.
I finally called a Cummins tech to check my boat with his computer. After a short run he said to return to the slip. He told me I was anal and to enjoy my boat, even Cummins allows a 5% difference between readings!
 
The computer, Ever time you go to neutral or hit the joy stick and let go they go back to center.
I guess when the factory install then there must have so kind of adjustment.
I ask the mechanical survey when I bought the boat if there was an adjustment and he said no it is a one time adjustment at setup .
 
I was just trying to figure out the same thing. What I found was when I had my tabs exactly the same I burned .7 gal/hr different. I also noticed my boat leaned to the port side. I always ran with auto trim on so didn’t pay much attention. Now I use auto to get up on plane then switch to manual and make a small adjustment to the tabs to even out and I burn exact same fuel/hr now. So try to adjust your trim tabs once on plane and see if that makes the difference for you too.

so i don't have auto glide, just the tabs on my pods. I'm not to familiar with them but in any event i would set at all the same and run it to see if it makes a difference. if the auto glide is moving those tabs it would be possible it is causing drag and could affect the fuel burn. Possible they are just not operating as designed?
 

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