As the name hints, navy strength gin is a powerfully alcoholic expression of the juniper-informed spirit, typically clocking in at 57 percent alcohol by volume. (Regular London dry style gin typically ranges between 40 percent and 45 percent.) Beginning in the early 19th century, it was supplied to the British Royal Navy by distillers such as Plymouth. The declared reason for the high alcohol content was that that was the proof level at which the ship’s gunpowder could still be fired should it accidentally get soaked with booze. Whatever M8.