The strength of beer is probably way too high. According to Wikipedia "The strength of beers has climbed during the later years of the 20th century. Vetter 33,

The strength of beer is probably way too high. According to Wikipedia "The strength of beers has climbed during the later years of the 20th century. Vetter 33, a 10.5% abv (33 degrees Plato, hence Vetter "33") doppelbock, was listed in the 1994 Guinness Book of World Records as the strongest beer at that time". So obviously, sailors during the age of sail couldn't have 13% ABV beer. They had rum though, so maybe the drinks they had were mixed with rum to reach 13%. If sailors were issue "strong beer", I would guess it is like today's regular beer, maybe in the order of 5-6%. As opposed to "small beer", that was maybe 1-2%. Sometimes it was less than 1%, not even enough to qualify as an alcoholic drink in many countries today. As for wine, it also tended to be weaker than modern wine, most likely under 10%, and it was often watered down. The reason beer and wine are so consistently strong today is that we have good knowledge of the fermentation process and we are able to precisely control all the variables. They didn't even know what kind of yeast that had back in the days, they mostly used what was floating in the air where they were. Now we have lab grown yeasts, selectively bred for maximum performance.