Note:  Do not rely on this information. It is very old.


Boom (cognate with beam) is a long stout spar run out from some part of a sailing vessel, to which the bottom of a sail is made fast in order to keep it extended. They have various names according to the sails made fast to them - topsail-boom, jib-boom, spritsail-boom, etc. The term is also applied to the stout spars run out from the deck of a modern ship of war. to make boats fast to when in harbour, or to suspend nets from as a protection against torpedoes; to the barriers of floating timber lashed together, which formerly sometimes in war blocked the entrance to a harbour, as at the siege of Derry in 1689; and to the dam of logs sometimes made by American lumbermen to obtain sufficient water to float down timber.