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.
More facts about supertankers:
- The average modern supertanker can carry more than two million barrels of oil. That's enough oil to power all US auto traffic simultaneously for almost four hours.
- The turning diameter of the average supertanker is about 1.2 miles (2 km).
- Supertankers are among the largest ships in the world — much bigger than aircraft carriers. The longest ship ever built as of 2010 is the Knock Nevis. It is over 1,500 feet (548 m) in length, which is slightly longer than the height of the Empire State building. After her final journey in 2009, the ship was beached for scrapping.
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More Info: en.wikipedia.org/wiki/Oil_tanker
Discussion Comments
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.
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.
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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