When costume designer Robert Fletcher approached Starfleet's uniforms for "STAR TREK II: The Wrath of Khan,” director Nicholas Meyer said, “OK if this is going to be the navy, let’s have them look like the navy."
Meyer had decided that his film would depict the voyages of Admiral James T. Kirk in the adventurous vein of C.S. Forester's Horatio Hornblower; a fictitious, heroic Napoleonic War-era Royal Navy commanding officer. He was the ultimate example of how Meyer saw Kirk, and so he requested ornate uniforms reminiscent of that romantic naval era.
Fletcher set to work designing the Wrath of Khan era Starfleet Uniform suite, including accouterments far more ornate and realistic. For that, he reached back to his own service in the Army Air Force during World War II, and set to work devising an intricate system of insignia and accouterments for Starfleet.
His rank pins are ingenious and take their inspiration from the ranks used in the U.S. Navy with a bit of futuristic panache. Sixteen rank pins in all from "AbleSeaman" all the way to the "Admiral of the Fleet."