Bitts

Bitts are paired vertical wooden or metal posts mounted either aboard a ship or on a wharf, pier, or quay.

[1] Bitts aboard wooden sailing ships (sometime called cable-bitts) were large vertical timbers mortised into the keel and used as the anchor cable attachment point.

[2] Bitts are carefully manufactured and maintained to avoid any sharp edges that might chafe and weaken the mooring lines.

[3] Mooring lines may be laid around the bitts either singly or in a figure-8 pattern with the friction against tension increasing with each successive turn.

As a verb bitt means to take another turn increasing the friction to slow or adjust a mooring ship's relative movement.