From Captain John Smith's Sea Grammar in 1627, "A Bitter is but the turne of a Cable about the Bits, and veare it out by little and little. And the Bitters end is that part of the Cable doth stay within boord."
A bitt is a post fastened in the deck of a ship, for fastening cables and ropes. When a rope is played out to the bitter end, it means there is no more rope to be used.
I have it on good authority from C.A.N.O.E. (the Committee to Ascribe a Naval Origin to Everything) that this is true.
The shackle holding the bitter end to the bulkhead in the chain locker will do absolutely nothing to stop a runaway anchor drop as the Tarawa (LHA-1) found out. Fifteen shots of chain weighing about eight tonnes each develops quite a lot on momentum.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)