Did pirates really drink a lot of rum?

Interest only:

Standard disclaimers: Correlation does not imply causation, YMMV, do not bend staple fold or mutilate, IANAL, DTTAH:

But

Googles NGram viewer returns the following interesting curve sets. The upper graph pair shows is a case insensitive search for "rum" and for "pirates" in English language documents in general.
The lower graph pair shows the same search in "English fiction".

Both graphs have the same frequency of occurrence in their body of literature per minor axis division but te upper graph is slightly more compressed physically. ie comparisons may be made in terms of eg vertical divisions rather than linear dimensions.

The real world results show a marked correspondence between occurrences of rum and of pirates with a few periods of substantial variation.

The fiction results suggest that rum gets increasing mention relative to pirates with time but that relative mention of both is higher than in the general literature.

The NGRam viewing system allows of access to the source documents so it would be possible to investigate the reasons for the patterns seen above. But, that may well spoil the fun.

The pirates, as well as regular navy sailors drank what was available. For example, the British sailors had regular rations of beer or wine. When this was not available, they drank rum or whatever was available. As rum was produced in large quantities in the Caribbean, it was the most common alcoholic drink there. As the most common pirates in the popular literature and movies operate in the Caribbean, they usually drink rum.

It is hard to imagine Mediterranean pirates drinking rum. Or those in the China seas.

Origins and availability or the drink aside (this was covered by Rico and the Major already)... life on a sailing ship was hard.

Especially ships prepared for combat -- like a navy's warships -- had large crews, which made for very cramped living and no privacy. The work aboard was hard and dangerous, and that's before the guns were run out to engage an enemy. So there were strict rules, ruthlessly enforced to keep discipline up.

Rations aboard were pretty monotonous as well -- few provisions survived longer than a few days in the hot-humid conditions of the Caribbean, and you ended up with, basically, hardtack, jerky, and bean sprouts (if you were lucky) resp. scurvy (if you weren't lucky).

It's somewhat easy to see how discontent and mutiny might arise from such conditions.

Add rum, a cheap, non-perishable drink with lots of rations to be had from a single barrel (especially if you use it to make Grog). Their daily rum ration was something the sailors could look forward to at the end of their shift. If you give them just enough, you'll have sailors that are happy, then sleepy, but not mutinous. You also get a disciplinary measure (taking away their ration for the day) that doesn't chafe just as bad as harder work or the whip would.

And once the battle begins, you get anaesthetic and disinfectant out of the same barrel.

So now we know where the "rum ration" comes from on a navy warship. Now picture a pirate's vessel: Usually smaller, just as cramped, with all the possibilities of poorer provisioning and / or less discipline... and you'll see how more rum might actually seem like not a bad idea at all.

Historical evidence suggests, and I am writing from the wiki article of origin of Rum, that during the late 16th and early 17th century, sugarcane plantation slaves in the Caribbean islands discovered a byproduct of sugar-making i.e. Molasses can be converted to an alcoholic beverage. After fine tuning the distillation process they produced the refined Rum. And thus, the origin of Rum can be attributed to the Atlantic region of Caribbean - West Indies.

Now this era (late 16th - early 17th) was the Age of Sail, and all the European powers (British, Dutch, Spanish, Portugeese, French etc etc.) had colonial interests in the New-World (Americas). Thus, it also ushered in the era of piracy and also state sponsored privateering.

Historically, the association of Rum and Pirates was enforced during the Rum-Ration given by the Royal Navy to its Privateers (replacing French Brandy). Many of the privateers later became pirates or buccaneers raiding Spanish flotillas. Since, Rum was in abundance in their area of operation (i.e. Atlantic and Caribbean) it became their favorite beverage.

From a literary point of view, the association of Rum and Pirates was enforced by R.L.Stevenson's Treasure Island. Pirate characters such as, Capt. Billy Bones and Capt. Flint had been depicted as having high affinity to Rum.

All this combined, we see, Jack Sparrow saying sadly-- "why is always the rum gone??" when rum goes missing.

Further, from an actual reason of having abundant Rum onboard ships was to be used as Preservative (thanx to Maj. Stackings for pointing it out), there is an anecdote in the English navy that, after the Battle of Trafalgar, the body of the victorious Admiral Horatio who died during the battle was put inside a Rum Barrel to be transported to England. But when they opened the barrel in England, it was found empty, thus giving rise to the Royal Navy slang - Tapping the Admiral.

EDIT - In reality the body of Lord Nelson was preserved in barrel of Brandy under supervision of surgeon of the navy William Beatty. The barrel was refilled with wine because brandy was absorbed by the dead tissue. This incident might have given rise to the anecdote. But still, rum has always been an integral part of naval activities till the advent of more modern rations and amenities.