Boat Winch Handles & Winch Handle Pockets
Winch handles are generally 8" or 10" in length and have a variety of styles. Most have a lock-in function securing them in the winch when in use with a range of release options to avoid them being lost overboard.
There are winch handles that float as well, so if the worst does happen and it goes overboard there is some chance of recovering it.
Force 4 Video: How To Pick, Install and Service Lewmar Winches