This song may or may not be a fo'c's'le shanty, but it is a sea song. When the British got control of Jamaica, what had been the sailor's daily ration of a gallon of beer a day was switched to a half pint of rum daily per man with considerable savings of storage space. However, some sailors would hoard their rum ration for several days, then drink it all at once. As a result of the ensuing drunkenness and disciplinary problems, it was decreed that this half-pint should be mixed with a quart of water and issued in two servings, one before noon and the other after work. For the ships under his command Admiral Edward Vernon ordered lime or lemon juice to be added to the mixture, to mask the water's foulness. Vernon habitually wore a cloak made of Grogram (a mixture of silk and wool) and was known by his men as 'Old Grog': and his name was soon attached to the daily watered rum ration. It was served as a ration in the US Navy until 1862 and in the Royal Navy until 1970. I learned this at one of the Sunhearth gatherings long ago.