Supertankers | The Largest Ship Tankers – Geographic History.
“Supertankers” are the largest tankers, including very large crude carriers (VLCC) and ULCCs with capacities over 250,000 DWT. These ships can transport 2,000,000 barrels (320,000 m3) of oil/318,000 metric tons. By way of comparison, the United Kingdom consumed about 1.6 million barrels (250,000 m3) of oil per day in 2009. ULCCs, commissioned in the 1970s, were the largest vessels ever built, but the longest ones have already been scrapped. By 2013 only a few ULCCs remain in service, none of which are more than 400 meters long.
Because of their great size, supertankers often can not enter port fully loaded. These ships can take on their cargo at off-shore platforms and single-point moorings. On the other end of the journey, they often pump their cargo off to smaller tankers at designated lightering points off-coast. A supertanker’s routes are generally long, requiring it to stay at sea for extended periods, up to and beyond seventy days at a time.
Read More: https://en.wikipedia.org/wiki/Oil_tanker