It takes about 20 minutes for a fully loaded supertanker to stop when traveling at normal speed. In emergency situations, some can perform a "crash stop" maneuver, which can cut the time down to 14 minutes. The reason supertankers, also known as oil tankers, take so long to stop is the huge amount of momentum they build up as they sail. Because of this huge momentum, most supertankers turn off their engines about 15 miles (25 km) away from their dock.

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anon357613 December 5, 2013 I'm a Deck Officer on oil tankers, with several contracts on VLCCs of 330+ meters. We don't stop engines and 'coast'; we gradually reduce speed to 5 knots or less coming into port, stop the vessel off the jetty and are maneuvered into position with small engine movements and use of tugboats. However, during ship to ship transfers, both tankers are moving and very gradually (few degrees of heading at a time) come alongside. We use giant fenders to prevent damage.

anon357590 December 5, 2013 They don't shut their engines completely off. They might throttle back to neutral until they slow down enough for the tugs to put the pilot on board and bring the ship into the dock. But they don't turn their engines off until they're secure at the dock. Source: I worked on tugboats in Alaska.

anon357520 December 4, 2013 It seems to me that a ship that large would never be allowed to coast up to a dock. I bet that they always have tugboats and pilots coordinate a save docking.

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