Cobbing is a form of spanking using a type of paddle known as a cob or in full cobbing-board, typically used as a disciplinary measure, often by comrades, in the military or among sailors. In the context of the Royal Navy, it also refers to any informal use of Corporal Punishment which could use a variety of implements.
During the Nineteenth century, a cobbing on board a ship of the Royal Navy could be inflicted with a sword scabbard or a rope's end. There are even reports of stockings filled with sand being used, though this would be completely unsuitable in a BDSM context dure to the risk of serious injury. When cobbing was conducted between midshipmen during this period, the sword scabbard would be that of a midshipman's dirk. This is a short sword 23 inches in length with a blade 19 inches in length. The scabbard would be made of leather but with the tip encased in brass in order to protect it. The result would probably have been like an Irish strap. As time progressed so did the implements used, with the rope's end and dirk scabbard falling out of use and a midshipman of the early twentieth century more likely to be having to bend over for the cane.
Sources and Notes
Walker C. F. Young Gentlemen: The Story of Midshipmen 1938