FYI: What Kind Of Gas Mileage Can You Get From A Naval Warship?

By Daniel Engber Posted 10.17.2012 at 9:01 am 8 Comments

Destroyer Stocktrek/Getty Images

A hulking Arleigh Burke–class destroyer might typically burn a minimum of about 24 barrels (1,000 gallons) of fuel per hour, but this figure conceals so many factors and variables that the Navy doesn’t really use it the way we use “miles per gallon.” Wind and current can have a major effect on a ship’s efficiency. Speed affects a ship’s mileage in unique ways, too, says Gabor Karafiath, with the Naval Surface Warfare Center in Bethesda, Maryland. When a ship moves quickly, he says, “it takes an inordinately greater effort to push it through the water because it makes bigger and bigger waves.”

Other subtleties arise from a ship’s engine setup. Arleigh Burke–class destroyers are fitted with four gas turbine propulsion engines (which are most efficient at high RPMs), so depending on the speed required, one engine going full tilt is more efficient than splitting the work across two engines. The USS Chafee burned similar amounts of propulsion fuel overall in May and July 2010, but in July its efficiency turned out to be 72 percent higher; that month the ship operated mostly with one engine cranking at maximum capacity versus using multiple engines running at lower ones.

tl;dr: With ships, there’s no such thing as “highway” and “city” mileage.

Have a burning science question you'd like to see answered in our FYI section? Email it to fyi@popsci.com.

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8 Comments

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quasi44

09/29/12 at 1:25 am

The easiest answer to the question in the headline starts with how much of the energy potential of the fuel are they using subprocessing and reinjection for one engine, before it ever gets to a ship. They ain't gonna talk about that so no way to get any answer at all. We don't know current displacement at all so that's out, nor drive configuration efficiencies. We don't know direction opposition specifics for any patch of water one might be in anywhere near the grade of data the ship collects. With zero questions answered, the basic requirement of secrecy is achieved. PopSci, someone shoulda seen this coming. We've been racing multi engined mountain motors on advanced fuels in custom tractors for decades now and planes and rockets before that but the only thing we know for sure about those ships is that they float on Earth normal water and can blow the crap outta things.

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ggrahn

10/02/12 at 10:14 am

Too bad, too, that the picture was a Knox class frigate (USS Badger), decommissioned in Dec 1991, that had two 1200psi boilers driving one Westinghouse geared turbine with one shaft = rated at 35,000 shaft horsepower

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Robot

10/17/12 at 9:31 am

A ship or any type of military vehicle or weapon is design to accomplish a mission paid by the tax payers.

If our Navy Ship achieves their mission in a cost\effect manner of which the USA people agree with, then they are efficient\effective.

While reducing cost is always important, we are always increasing our effectiveness, which comes at a premium too.

After all the dollars are spent, are we achieving our mission goals at a price we are willing to pay?

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Cookiees453

10/17/12 at 11:27 am

It's really sad that humanity still uses fossil fuels. You'd think by now, that every car would be running on Mr. Fusion. I suppose that's another hundred years away though, oh well.

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theLordsDevil

10/17/12 at 5:00 pm

And now do you see why the average automobile driver is getting bent over by environmentalists. They complain and the stuff rolls down hill. Cars are a drop in the bucket when it comes to pollution. Instead the average person pays through the nose for standards that have little impact when one of these destroyers pretty much voids the total advantage gained by the current run of EVs.

Stupid humans.

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riff_raff

10/17/12 at 11:23 pm

".....her subtleties arise from a ship’s engine setup. Arleigh Burke–class destroyers are fitted with four gas turbine propulsion engines (which are most efficient at high RPMs)..."

Turboshaft engines are not most efficient at high rpm's. They are most efficient operating at a specific design speed and pressure ratio (or load). The most efficient warships use a combination of recip piston diesel engines for cruise, and turboshaft engines when high dash speeds are needed.

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beefymclovin

10/18/12 at 7:54 pm

Cookiees453 ford did look into a nuclear powered car in the 1950s..

why we build cars to run on gas i will never get, henry ford had the right idea, hemp cars running on hemp oil.

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jerrydd

10/20/12 at 3:43 pm

jerrydd

That these are not powered by hyperion style lead cooled reactors for a fraction of the cost means we'll keep fighting oil wars and won't be able to afford them in 10 yrs.