But despite its streamline design, the shark-shaped ship travels at an average speed of just 7.5 knots -- about that of a large ocean liner.

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By some estimates, American navy ships spend 80% of their time travelling at half speed, which requires barely one-eighth of the power needed to propel a ship at top speed.

ECONOMIST: Electric ships

When the Alcubierre-driven ship decelerates from superluminal speed, the particles its bubble has gathered are released in energetic outbursts.

MSN: Warp speed? Slowing down could be a real killer

The pirates raced toward the ship, the Captain Maslov, in a high-speed boat late Thursday afternoon and attacked as it headed from Colombo, Sri Lanka, to Mombasa, Kenya, the ministry said.

CNN: Ship escapes pirate attack off Somalia, Russia says

They were even more impressed after the ship set sail and destroyed the speed record by crossing the Atlantic in a record three-days and 10-hours.

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Working at a speed of two knots, HMS Protector broke the four-metre thick ice, which had trapped the cruise ship's bow, in two hours.

BBC: HMS Protector approaches MS Fram