Foul is a nautical term meaning to entangle or entwine, and more generally that something is wrong or difficult. The term dates back to usage with wind-driven sailing ships.
It is usually applied to the state of an anchor, which has become hooked on some impediment on the ground, or has its cable wound round the stock or flukes. The term is generally utilized when speaking of items of historical value such as the US Navy chief petty officer emblem. The fouled anchor is also the official seal of the Lord High Admiral of Britain, presently HRH Prince Philip, The Duke of Edinburgh, and is flown on the ship carrying the monarch to sea. It is also flown during the launching of a warship of the Royal Navy.
The term can be applied to many nautical situations:
- Foul hawse — when a ship lying to two anchors gets the cables crossed.
- Foul bottom — in reference to a seafloor that has poor qualities for securing an anchor, such as hard rocks, coral, wreckage, or other impedents that would make securing or unsecuring an anchor difficult or impossible. Also, in reference to the hull of ship that is so encrusted with weeds and marine growth as to impede her progress.
- Foul wind — when a strong head wind prevents a sailing ship from keeping her desired course.
- Foul deck — on an aircraft carrier, when the deck is occupied by aircraft, thus preventing other aircraft from landing.
- The Oxford Companion to Ships and the Sea, Oxford , edited by Peter Kemp. ISBN 0-586-08308-1