The battleship is a gigantic, thirsty machine that could guzzle thousands of gallons of fuel per day.
Some of the largest battleships of the 20th century weighed up to 60,000 tons fully loaded, and some 15% of that was fuel.
Battleship engines pack an incredible 150,000 to 215,000 horsepower, enough to push the fastest vessels to over 30 knots. You’d be lucky to get 0.01 miles per gallon, with many battleships achieving fuel efficiencies as low as 0.005 miles per gallon.
This begs the question, how do battleships maintain their fuel demands? And how did navies manage the logistics of refuelling entire fleets of ships?
How Much Fuel Do Battleships Use?
It’s difficult to understate how fuel-hungry battleships are. HMS Dreadnought (1906) carried 2,868 long tons of coal and 1,120 long tons of fuel oil. At full capacity, the ship could travel 6,620 nautical miles (7,620 miles) at 10 knots.
A rough calculation suggests she consumed half a ton of fuel per mile. However, as the ship gets lighter, fuel efficiency increases.
Later oil-fuelled battleships were marginally more efficient. For example, the Iowa-class battleships of 1940 carried 8,841 long tons of fuel oil for a range of 15,900 nautical miles (18,300 miles) at 17 knots. This meant they used around 0.48 tons of fuel per hour, and had the added advantage of being considerably faster.
Battleships Fuel Usage by the Gallon
The quantity of fuel carried by battleships is measured in terms of displacement, which is the weight of water displaced by the ship when afloat.
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The fuel capacity of a battleship is typically expressed as a percentage of its displacement, known as the “fuel capacity ratio.”
For example, the Iowa-class battleships commissioned by the US Navy during WW2 had a fuel capacity ratio of approximately 18%. These large battleships had a displacement of about 45,000 tons, meaning they carried roughly 8,100 tons of fuel.
The USS North Carolina, launched in 1940, could achieve a fuel efficiency of 0.006 miles per gallon. In other words, the ship could move just 32 feet for every gallon of fuel consumed. The ship required 23 gallons (around 100 liters) of fuel to advance its own length.
Battleships are designed to carry enough fuel to operate for extended periods without needing to refuel at sea. Therefore, carrying a vast quantity of fuel was a priority. After all, running out of fuel in combat is far from ideal.
However, in the 18th century, it became apparent that at least having the ability to refuel at sea could prove a strategic advantage. Also, as the world globalized, ships had to travel further, which complicated the logistics of long-range missions.
Pre 19th-century
The Age of Sail spanned some 400 years between the 15th and 19th centuries. During this time, ships were solely powered by sails and oars, though oar-powered galleys declined as ships became larger and heavier. Steam-powered ships powered by coal increased in the early 18th century, but it wasn’t until around 1850 that France launched the first hybrid steam and sail battleship, Napoléon (1850), also the first screw-propelled battleship.
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Soon after, large mastless battleships appeared, starting with HMS Devastation, launched in July 1871.
These new steamships had an insatiable appetite for coal. Early steam battleships burned over 300 tons of coal daily and had to return to port every week or so for fuel. Lieutenant Robert Lowry was among the first to suggest large-scale underway replenishment (meaning refuelling at-sea) to the Royal Navy in 1883, though his ideas were continually rejected.
Cableway
The French were among the first to refuel battleships underway when they successfully refueled two battleships with 200 tons of coal at a speed of 6 knots in 1898.
Earlier, in 1887, the US Navy also proposed to tow coal supplies alongside ships and use a cableway to transport coal from the colliers to the vessel. In the Spanish-American war (1898), the US Navy blockaded the Spanish fleet off Cuba, and when they attempted to break the open sea, US ships were being refuelled some 45 miles away and couldn’t intervene.
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This ignited the US Navy’s interest in refuelling ships at sea, culminating in the invention of a device that suspended a taut cable between two ships so coal in water-tight containers could be winched from one side to the other. The device was first employed with the collier Marcellus and battleship Massachusetts.
Coal Underway Replenishment
Most efforts to refuel coal-fired ships at sea used a similar method to the US Navy’s method of towing a collier behind a ship and using large carts to pull the coal to the ship. This could achieve the transfer of around 30 tons of coal per hour. Later adaptations in 1902 and 1903 achieved a rate of 40 to 60 tons an hour.
The record for underway coaling is believed to be held by HMS King Edward VII, which allegedly received 1,180 long tons of coal at 289.2 long tons an hour, but that was only possible with virtually every crew member working at a back-breaking rate for hours.
In the end, early coal underway replenishment was rarely practical. The average battleship required some 2000 tons of coal, and even smaller destroyers required 200 to 300 tons. At average replenishment rates, a giant battleship would take 50 to 60 hours to refuel at sea.
Plus, both ships would need to maintain a slow, steady speed, which left them vulnerable. Add in adverse weather, and it became tough to argue that underway replenishment was more effective than simply heading to port.
Moreover, the labour required to replenish a ship at sea was extremely intensive. By the end of replenishment, sailors would be coated in thick, sweaty coal dust, which was notoriously tough to remove. In addition, the warship itself would be covered in coal, which had to be meticulously cleaned from every surface. To hear the call “Rig ship for coaling!” would instill dread in any sailor.
Progression to Oil
The first oil-fuelled warship was HMS Spiteful, a torpedo boat destroyer, launched in 1899 and modified for oil in 1904. The Majestic-class HMS Victorious was also converted from coal to oil engines in 1908. In 1906, the Royal Navy was experimenting with transferring oil between the oiler Petroleum and the Victorious. Oil was much easier to transfer from ship to ship, as it could be pumped through thick flexible tubes.
Initially, the Royal Navy used water to test the device and obtained a transfer rate of 115 tons per hour at 12 knots. Later, in 1911, oil underway refuelling was trialled at sea, where the oiler Burma successfully transferred several hundred tons of oil to a trio of destroyers.
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By 1906, naval operations had become more sustained, and the distances involved were much greater. This led to an explosion of other auxiliary ships that accompanied the main fleet, including colliers, hospital ships, ammo ships, hospital boats, and food supply boats.
For example, the US Great White Fleet launched by Roosevelt in 1907 consisted of 16 battleships and several auxiliary ships, including the USS Culgoa (storeship), USS Panther (repair ship), USS Glacier (storeship), and USS Relief (hospital ship).
WW1 and WW2
In WW1, refuelling smaller oil-fired destroyers at sea was fairly common, though it rarely took place in combat situations. Instead, underway replenishment helped support long-distance operations.
The US had extensive oil supplies, while Britain was experiencing a fuel shortage, so the USS Maumee, an oiler, was commissioned to refuel ships sent across the Atlantic to Britain. Between 1917 and 1920, Maumee refuelled 34 destroyers in the mid-Atlantic.
However, refuelling larger battleships at sea remained an essentially insurmountable challenge. Their sheer size, fuel consumption, and steerability rendered it highly inefficient, and dockside fuelling remained preferable until the Pacific War of WWII, when US ships were extensively refuelled underway by flexible supply ships.
WWII replenishment techniques developed into the US Navy’s Standard Tensioned Replenishment Alongside Method (STREAM), which enabled ships to refuel at a distance of up to 200ft from the oiler.
The Present Day
Replenishment oilers are still in operation in most navies, and modern-day replenishment is now reliable at 12 to 16 knots. After the Washington Treaty limited the size of new battleships, newer ships became increasingly smaller and fuel-efficient, rarely requiring underway replenishment. Aircraft carriers are more likely to be refuelled at sea.
Since the 1950s, fast combat support ships have gradually replaced oilers, combining three types of auxiliary ships into a singular all-in-one unit. Fast combat support ships combine fleet oilers (AO), ammunition ships (AE), and refrigerated stores ships (AF), with notable examples including the British Fort-class and Supply-class USNS Arctic.
These are among the largest combat ships on the sea, exceeding 200m in length. The US Supply-class ships can carry approximately 177,000 barrels of oil, 750 tons of food, and 2,150 tons of ammunition.
