I can't believe that Rulers of the Sea receives only a 6.6-star average on the IMDb.
This is a really good film. The acting of the three leads is fine, the sets are wonderful, and the way the story deals with the technical (the conquest of the Atlantic by steamships), the personal (the hardships of the inventor and his daughter, and the love between the daughter and the young captain who helps her father), and the political (the machinations of the various shipbuilders, machine shop owners, and capitalists who have interests for or against the new technology) is quite skillful.
It's not a fast-paced film, and so for people who want lots of action, it may seem dull. But it's a thoughtful film about a serious economic and humanitarian issue, with great actors in the leads and dozens of veteran character actors in the smaller parts.
I have a watchable but not very good quality copy on DVD-r which I purchased from an ebay merchant who had obviously pulled it off a television broadcast. If any company would put this out on a proper DVD I would gladly buy one, because the films looks impressive visually even on the DVD-r and would look spectacular in a cleaned-up edition.
1939 was a great year for films, and everyone knows of the big 10 or 15 films of that year. What most people don't realize is that there were just as many films in that year that were almost as good, or as good, as the more celebrated ones. Two 1939 comedies which are almost completely overlooked, Bachelor Father and Midnight, can hold their own with any screwball comedy. And there are many good dramas that hardly anyone hears about: In Name Only with Cary Grant; Juarez with Bette Davis and Brian Aherne; The Four Feathers; Rulers of the Sea, and many more.
Rulers of the Sea is a very competently executed story of early steamship travel. Lloyd knew his business as a director.
