What is navy strength gin?

Navy strength gin is almost always at 57 percent alcohol, the point that was called 100 degrees proof on the old British proof scale. Some brands bottle slightly higher or lower, but 57 is the reference.

That 57 comes from a measurement, not from a story. One hundred degrees proof was defined as a liquid with 12/13 of the specific gravity of the same volume of distilled water at 51 degrees Fahrenheit. Converted, that is 57.1 percent.

Anyone who comes across old bottles can calculate with it: alcohol percentage times 1.75 gives the British proof degrees. The United Kingdom dropped that scale on 1 January 1980 and switched to alcohol percentage by volume.

British customs and excise needed proof of the strength of drink, because the levy differed per strength. According to Scotchwhisky.com, the term proof first appears in seventeenth-century Great Britain.

The earliest test used gunpowder. A little powder was soaked with the drink and set alight; if it burned with a steady flame, the drink counted as 100 proof. From 1740 the customs adopted a safer method.

The breakthrough came with Bartholomew Sikes, who in 1816 presented a hydrometer that determined strength via specific gravity. His method was laid down in law in 1818 and remained in use for well over a century and a half.

On 19 February 1866 the Royal Navy rum ration was set at 54.5 percent alcohol.

Two later measurements are consistent with that: the Black Tot Last Consignment came out at 54.3 percent and the original Pusser’s from 1979 at 54.5 percent.

The 57 percent of navy strength comes from the tax side. One hundred degrees proof on the Sikes scale was equal to 57.1 percent, and that is the strength producers use today when they put navy strength on the label.

Navy strength only appeared as a label term late: Plymouth put it on the bottle in 1993, according to the overview by Matt Pietrek. The naval history behind it is much older than the brand name.

Rum came on board the Royal Navy in the middle of the seventeenth century. In the 1740s, Admiral Edward Vernon split the daily ration of 8 ounces, about 237 millilitres, into two portions and had the rum diluted with four parts water. The mixture was named grog after his nickname.

The ration lasted until 31 July 1970, the day known as Black Tot Day. The last tot was served on board HMS Fife in Pearl Harbor.

Regulation (EU) 2019/787 has no navy strength category; the word does not appear in Annex I. What is there is the gin category, number 20 of the 44 categories.

That category sets three requirements. Gin is a juniper-flavoured drink based on ethyl alcohol of agricultural origin. The minimum alcohol content is 37.5 percent. And only flavourings or flavouring preparations may be used, so that the taste is predominantly that of juniper.

A navy strength gin is therefore legally simply gin, distilled gin or London gin, with a trade designation added. If such a bottle also wants to call itself London gin, stricter rules apply: the distillate must be at least 70 percent, the ethyl alcohol used may contain at most 5 grams of methanol per hectolitre, colouring is not allowed and sweetening at most 0.1 gram per litre.