Why sailors received a gallon of beer

Was the Royal Navy's gallon of beer per day the largest naval alcohol ration, and why was it so large?

It may have been the largest formal ration, but weak beer functioned as safe hydration and liquid food, supplying calories and nutrients rather than simply intoxicating sailors.

No larger formal ration comes to mind in the answer, although the comparison is tentative. Beer is described as liquid bread because it supplied carbohydrates and energy as well as vitamins and minerals. It also offered a drinking option when the cleanliness of water could not be assured. The explanation places the beer at roughly 2 to 3 percent alcohol by volume and stresses that sailors drank the ration throughout the day. That distinction matters when considering how an imperial gallon could be compatible with working aboard ship. Better water handling and onboard fresh-water production later changed the supply problem, even while alcohol remained in naval rations.