# How far will 12 gallons of diesel get me?



## abrahamx (Apr 3, 2006)

As a new boat owner I have a Tartan 30 that was just refitted with a 12 gallon tank. About how far will this safely take me before having to stop for gas? 20 hp beta diesel.


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## capta (Jun 27, 2011)

How much fuel do you burn an hour at what speed?
Divide the 12 gallons by the hours you can run and multiply by speed should give you how far. For instance; @ 1/2 gallon an hour you can run for 24 hours. If you use 1/2 gallon an hour at 5.5 knots then you can run 132 miles. Of course, if your bottom isn't clean or you encounter any current, these calculations will no longer be accurate.
I would never willingly run a tank dry, so perhaps I'd take off 10% leaving 118.8 miles or 21.6 hours, but that's a personal choice.


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## chuck53 (Oct 13, 2009)

1/2 gallon an hour sounds about right.
I've got a 25 gallon tank in my 34 footer and I wish is was 1/2 that size. Meaning my fuel would turn over more often and wouldn't have much chance of getting old and stale.
Many sailboaters might only fill their tanks once or twice a year. Last year, we were on the boat quite a bit but mostly at the dock. I never went to the fuel dock once.


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## Minnesail (Feb 19, 2013)

Yeah, you'll have to figure out how much you burn per hour. Fill the tank, motor for a while at a set RPM (say 2500rpm), then fill again and divide the gallons by the time motored to give you gallons per hour. I'm pretty new to sailing, but from my limited knowledge I'd guess you'd get maybe 0.3 gallons per hour.

I was also taught that you should leave 10% reserve in your tank, so that gives you 10.8 gallons of useable fuel. 10.8 divided by 0.3 equal 36 hours of motoring time. If you motor at 5 knots that's 180 nm.

Anyway, it's something you'll have to work out specific to your boat.


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## fryewe (Dec 4, 2004)

Performance curves at betamarine.co.uk show fuel burn of 1.3 to 2.0 liters/hour in flat part of performance curve (about 2400 to 2800rpm which is 70 percent of full power and generally the most economical place to operate if your engine is properly sized to your boat). About 1 2/3 L/hr at 2600 rpm. Goes to above 4L/hr at 3600rpm.

5.5 knots is probably a good estimate of speed for your boat at 2600 rpm.

Your 12 gal tank is a bit over 45 liters. If you reserve ten percent that gives you 40 liters for comfortable steaming range (if your tank is clean with no water in the tank).

40 liters used at 5/3 liters/hr is 24 hours of operation.

24 hours at 5.5 knots is 132 nm of range (in flat water with no contrary current and minimal wind on the nose).

But...as stated above you should evaluate your range based on measurements you make on your boat as you operate it.


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## abrahamx (Apr 3, 2006)

I ofcourse will make my own determination eventually but thought I would ask. thank you. That defiantly helps.


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## wavedancer38 (Sep 11, 2009)

Unless you have recently polished your tank, I would not go below 1/4 tank. We jst had our tank polished for the first time after 10 years. When they removed the fuel, 8 out of the 10 gallons were sludge and water. Glad I never went below 1/4 tank!


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## bobperry (Apr 29, 2011)

I usually figure 1 gal per hour for every 30 hp you use. So on your engine I'd estimate .5 gals per hour.


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## flyingwelshman (Aug 5, 2007)

This chart is for Yanmar engines, but I imagine it provides a decent benchmark: Yanmar Engine Fuel Consumption in U.S. Gallons per Hour


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## baboon (Aug 7, 2008)

My T30 with a 20 hp 3 cyl diesel and fixed 2 blade prop burns 1/3 gal/hour at 2000-2100 rpm. This gives a cruising speed of 4.5-5 kts.


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## MarioG (Sep 6, 2009)

Now you have all the technical info I let you know, we went from North Myrtle Beach SC to Miami on a 12 gallon tank. A lot of that was done under sail alone and I hope that is what you are striving for.


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## deltaten (Oct 10, 2012)

My beta20 does just as mentioned..... =< half gallon/hr @ 5+ kts.


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## abrahamx (Apr 3, 2006)

baboon said:


> My T30 with a 20 hp 3 cyl diesel and fixed 2 blade prop burns 1/3 gal/hour at 2000-2100 rpm. This gives a cruising speed of 4.5-5 kts.


Thanks, I always thought you had a 27 for some reason. You have the 20hp 3 cyl as well ha? The beta site recommends the 16 hp but states that one owner went with a 20. I always assumed that was my boat they were talking about. One thing I never understood is why they recommend a 16 hp and say 20 is way more than enough even though it came with a 30 hp engine to start with? also the fuel tank is only about a year old if that.


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## Seaduction (Oct 24, 2011)

abrahamx said:


> As a new boat owner I have a Tartan 30 that was just refitted with a 12 gallon tank. About how far will this safely take me before having to stop for gas? 20 hp beta diesel.


OH NO! Don't put gas in that diesel!


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## RobGallagher (Aug 22, 2001)

abrahamx said:


> Thanks, I always thought you had a 27 for some reason. You have the 20hp 3 cyl as well ha? The beta site recommends the 16 hp but states that one owner went with a 20. I always assumed that was my boat they were talking about. One thing I never understood is why they recommend a 16 hp and say 20 is way more than enough even though it came with a 30 hp engine to start with? also the fuel tank is only about a year old if that.


If, when you say 30 HP, you are referring to the A-4 with direct drive then it probably did not put out more than 18 HP at the prop. With the typical over-propping of the day I'm gonna go out on a limb and say it was closer to 15 HP.

The A-4 was capable of making 30 HP, but on most sailboats it never did. Great engine though.

YMMV.

Rob


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## Jeff_H (Feb 26, 2000)

abrahamx said:


> Thanks, I always thought you had a 27 for some reason. You have the 20hp 3 cyl as well ha? The beta site recommends the 16 hp but states that one owner went with a 20. I always assumed that was my boat they were talking about. One thing I never understood is why they recommend a 16 hp and say 20 is way more than enough even though it came with a 30 hp engine to start with? also the fuel tank is only about a year old if that.


There are a range of reasons that this might be accurate. Diesels have a lot more torque for their rated HP and torque is thought to be more critical than HP on a sailboat engine.

The other thing is that there were only a very limited number of gas marine engines avail at the time when you boat was built and the Atomic 4 was pretty much it when it came to gas engines for a 30 footer.


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## blutoyz (Oct 28, 2012)

I am almost at the 1/2 mark on my 20 gallon tank for my 13HP volvo. I haven't done the gal/hr but I just felt like bragging since I go out 1-2 times/week since Memorial day weekend.
I do have 1/2 hour transit to raise the sails


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## denverd0n (Jun 20, 2008)

These estimates that you're getting are fine as a starting point, but there are a whole host of variables that can make your actual numbers significantly better or worse (though usually worse). Things like prop dimensions, how clean your bottom is, how fast you try to go, traveling with or against wind and current, how well tuned is your engine, how clean is your air filter, and so forth.

That's why you definitely must start out conservatively and work up your own numbers. Personally, I wouldn't run the tank below half until I had gotten enough time in, and collected the numbers long enough, that I had a very solid idea of just how much diesel I was actually burning.

Good luck.


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## tommays (Sep 9, 2008)

I actuality have A NEMA 2000 fuel flow on the Atomic 4 powered Cal 29 and while it is a gasoline motor 

At 4 knots it burns about .4 to .5 gallons per hour and at 5.5 knots your in the 1 gallon per hour range 

If you push it up to the 6.5 knot max the stern sinks real deep you feet get real wet and the burn goes up above 1.5 gallons per hour 


During last weeks 200 mile cruise i only had to motor one day which is a record for me on a trip that long and it is fairly amazing how much minor changes in wind direction, wind speed and current had on the range

The GPS unit has every conceivable fuel setting once you plug in the sensor including tank size and makes on the fly range calculations as conditions change bot my range is a low as 65 miles and as high as 120


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## dvuyxx (Jun 23, 2009)

Our Westerbeke 30 seems to burn 0.75 gph at cruising speed.


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## blt2ski (May 5, 2005)

abrahamx said:


> As a new boat owner I have a Tartan 30 that was just refitted with a 12 gallon tank. About how far will this safely take me before having to stop for gas? 20 hp beta diesel.


I personally would stop at all for gas....diesel mind you, I would! Gas might get you 10 or so min then all holy hellicopter will occur, worst than a clogged filter mind you!

My Yanmar 18HP 2 cyl nets me about 1/2 gal an hr at 6 knots, get to 6.6 or hull speed for my boat, probably more the size of a tartan 28 if there is such a creature uses about double the fuel. That last knot or so to hull speed will kill the gals and hr useage. I try to not go much more than 6. I also do not have a tach, so do not know how many rpm's I am using either. ALtho the motor does get a LOT noisier in that last .6 knots! Being as I have lost a bit of my hearing, for me to say that, is something to think about.

Marty


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## Waltthesalt (Sep 22, 2009)

Might want to know how far your suction tube is above the bottom. Add about an inch or two for being other than level and that's the usable volume.


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