Coal and The Kaiser is a set of “low to moderate complexity” rules for surface naval combat in the 1904 – 1918 era. The author writes:

This is a game of low to moderate complexity portraying tactical naval combat in the period from 1904 through 1918. While it will not yet you play Jutland in a day, it will let you play some fairly large actions reasonably quickly. It uses a scale of 4 minutes to the game turn and 1000 yards to an inch on the playing surface. The rules focus on big ships and big guns: battleships (and particularly the Dreadnought-type battleships that began service in 1905), battlecruisers and armored cruisers. Rules for smaller ships are meant to facilitate fast play and authentic tactics. I consider the rules to be at the beta test stage; I’ve tested them myself over a period of three years, and have started to play test them with others face to face.