Lightering is the process of removing oil or other hazardous chemicals from a compromised vessel to another vessel to prevent oil from spilling into the surrounding waters

Exxon Valdez

Lightering has been successful in several historic disasters including the 1989 Exxon Valdez oil spill. In that case, oil was lightered or transferred from the Exxon Valdez (left) to the Exxon Baton Rouge (right), to prevent remaining oil from spilling into Prince William Sound.

Lightering is not possible in all oil spill scenarios. It depends on many factors including the type of oil that is spilled. As time passes, the oil can become more viscous, or thicker, and therefore more difficult to pump. This can, in turn, make lightering difficult, if not impossible. While there are benefits to removing oil in this way, there can also be accidents and spills that result from lightering.

Lightering is also used to transfer cargo between vessels of different sizes like a barge and a bulker or oil tanker to reduce the vessel's draft in order to enter port facilities.

For more information:
Office of Response and Restoration

Office of Coast Survey