During the period between 1920 and 1933, the US governemnt forbade the sale of any alcoholic drinks. This period was known as Prohibition. Since in this story the ship was sailing from San Fransisco, it was "bone-dry", which means that no alcohol was sold on the ship. Although the sale of alcohol was illegal, it was possible to buy it on the black market, as Mr. Kelada obviously had.
The prohibition was made with the hope of correcting the society, and to make a better place. However, this didn't work because you can still get alcohol from the black market.
Watch the video below for further information and clarification.
The game below is a game for you in order to check your understanding of the story:
view.genial.ly/64b2e1318808420012775a3e/interactive-content-genial-quiz