17.2 gph average for first two tanks - 2000 410DA 3126 CAT

markrinker

markrinker

New Member
Jul 19, 2011
325
Lake Union - Seattle, WA
Boat Info
2000 410DA
Engines
Caterpillar 3126
...no MPG stat available at this writing because speed sensor is out and not recording miles. This measurement was based on two fillups totalling over 400 gallons with lots of mixed cruising around the Apostle Islands. Once the sender is replaced, I'll post some GPH and MPG stats as we plan a long cruise later this summer.
 
Without knowing your speed or at least average speed, we can't tell if that is great or terrible. But, as long as you are enjoying the ride, who cares! Unless of course you want to make sure your engines are running well.
 
I have found the CAT stats for GPH and RPM speed are not accurate on my boat.....
 
Last two trips (still without benefit of odometer) burned a little over 20gph over 60+ mile cruise, much of it at or above 2500rpm/30mph. The following weekend of more moderate on plane running at 2100-2300rpms at 24-26mph yielded 14gph....

Since we are scuba diving (location hopping) we don't spend much time idling or at 'cocktail cruise' speeds. Its usually startup, warmup, then quickly on-plane to a new destination, or back to the marina.

Next week we start a two week trip that will cover 300+ miles and I'll carefully measure and record miles, gallons, and hours. I think the sweet spot for this hull and engines is 2200rpm, as surface conditions allow. Interestingly, there is a distinctive turbo 'whistle' that accompanies that RPM, and with the trim tabs fully up the underhull exhaust note is also unique.
 
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quality time said:
Exactly what I found. My 380 was dialed in nicely toward the end of my ownership and it burned 26-27 GPH @ 2400 (24 kts) per Floscans. I believe the CAT table shows 20 or 22 GPH?
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Wow. I am pretty sure I could run my 410 at WOT/32mph and never get to those burn rate numbers. What gives???
 
The 20gph numbers were as close to a WOT throttle thrash as I'll probably get. We filled before leaving, covered 80+ miles in 3.5 clock hours and refilled with 70 gallons at return. Granted I wasn't pinned at 2800rpm every moment of the trip, but lots of the crossing were WOT because it was running good and super smooth on Superior, which is unusual.
 
14gph sounds like each engine to me. Impossible to push a 41' boat with 3126's at 2100 to 2300 rpm and only burn 7 gph per engine. Can you clarify?
 
And you may not have filled the tanks with only 70 gallons after running 80 miles in 3.5 hours. Depending on the diesel pump at the fuel station, sometimes when the diesel comes out too fast from the pump, it backs up and shuts the pump, as if your tank is full, but it isn't. Also, if you were running at 30 plus miles per hour, 80 miles would have taken less than 3 hours, so something is not adding up.
 
Dani-Lu said:
And you may not have filled the tanks with only 70 gallons after running 80 miles in 3.5 hours. Depending on the diesel pump at the fuel station, sometimes when the diesel comes out too fast from the pump, it backs up and shuts the pump, as if your tank is full, but it isn't. Also, if you were running at 30 plus miles per hour, 80 miles would have taken less than 3 hours, so something is not adding up.
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Agreed. My estimated distances reported are a huge variable, as my odometer has been out and I have been negligent in getting the sender installed, even though I have it in hand.

As for filling variances, boats are a breeze compared to trucks. Why? They are very level. We fill with the same method of listening at the vent for when the tank fills, and fuel begins to back up into the filler hose. That is when we stop. Usually the amount of fuel added port and starboard is within a few tenths, unless of course the genset was run.

The only significant numbers are averages gained over long hours, miles, many gallons. All variances are minimized with large sample sizes.

At the end of this season, I'll know average GPH burned but I won't know average MPG. At the end of our two week vacation that starts this Saturday, I'll know both GPH and MPG.

From what I have seen so far, my observation is this: The last 500rpms and 5mph is VERY VERY expensive in these boats. Running with throttles pinned at 2800rpm is a wasteful habit that should be broken, unless you enjoy being the 'high GPH' king. 2100-2300 is clearly the sweet spot, all factors of MPH, GPH, MPG considered.

Probably is a bit easier on the CATS as well.
 
Last edited:
quality time said:
Exactly what I found. My 380 was dialed in nicely toward the end of my ownership and it burned 26-27 GPH @ 2400 (24 kts) per Floscans. I believe the CAT table shows 20 or 22 GPH?
Click to expand...

So far my numbers would be much closer to the CAT tables than yours, at that RPM. I will provide more statistically accurate (larger sample size) averages of GPH burned so far this season, and 400+ miles of cruising data, over the next two weeks.

The boat will be operated on step, at 2100-2400rpm max based on wind and wave conditions. I will probably hit 2800rpms once each tank to verify that the fuel filters are clear enough to allow for rated WOT, but that is all.
 
Don't know who Wingle$$ is, or what his 'talk' is, but I do know numbers and averages and who would burn less fuel if you and I went out for a side by side cruise... ;)
 
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