Posted by Roland Collins on August 26, 2004
Recently * Danger Kitty * on July 15, 2004 asked for the exact meaning of "jump ship".
It means to to abandon one's post and desert the ship.
Sailors when joining a ship are required to "sign on" for the duration of the voyage. They are "bound" to the ship and ordinarily cannot leave it until the voyage ends or the ship returns to home port.
This is to ensure the safety of a ship at sea and prevent its safety being jeopardized by irresponsible crew. There is a "statute of limitations" which has a legal binding for I believe 2 years, after which a sailor must be granted leave if requested. This was certainly the case during my times of "signing on".
In ancient times a sailor wishing to leave without authorization would jump over the side when near to land (hopefully unnoticed) and swim for it, hence the expression to jump ship, meaning to abandon your post and desert the ship.