|Article source: http://www.csp.navy.mil/sailors.htm
The insignia of the U.S. Navy's Submarine Service is a Submarine flanked by two dolphins. Dolphins, the traditional attendants to Poseidon, the Greek god of the sea and patron deity of sailors, are symbolic of a calm sea.
The origin of the U.S. Navy Submarine Insignia dates back to 13 June 1923. Captain Ernest J. King, USN,Commander, Submarine Division Three (later Fleet Admiral and Chief of Naval Operations during World War II), suggested to the Secretary of the Navy, via the Bureau of Navigation (later known as BUPERS), that a distinguished device for qualified submariners be adopted. He submitted a pen-and-ink sketch of his own showing a shield mounted on the beam of a submarine, with dolphins forward and aft of the conning tower. The suggestion was strongly endorsed by Commander Submarine Divisions, Atlantic. During the next several months the Bureau of Navigation solicited additional designs from several sources. Among the designs were a submarine and shark motif, a submarine and shield, and submarines with ancient dolphins.
A Philadelphia firm, Bailey, Banks and Biddle, which had done work for the Navy previously, was requested to design a suitable badge. In 1928, Mr. George Meale, representing the firm, mentioned to Ensign William Crawford Eddy that they were looking for a design for "Submarine Wings" to denote qualifications in Submarines. Using his original sketches of the 1926 Naval Academy class crest that he had designed, Eddy came up with the present submarine insignia which was adopted by the Navy and is in use today (shown above), abow view of surface submarine, with bow planes rigged for diving, flanked by dolphins in horizontal position, their heads resting on the upper edge of the bow planes. Future Navy Captain Eddy then recommended to the Secretary of the Navy that the design be adopted. The recommendation was accepted by Theodore Roosevelt, Jr., Acting Secretary of the Navy. The submarine insignia was to be worn at all times by officers and men qualified in submarine duty attached to submarine units or organizations, ashore or afloat, and not to be worn when not attached.
In 1941 the Uniform Regulations were modified to permit officers and enlisted men to wear the submarine insignia after they had been assigned to other duties in the naval service, unless such right had been revoked. The officer insignia was a bronze gold plated metal pin, worn centered above the left breast pocket and above the ribbons or medals. Enlisted men wore an embroidered silk insignia on the outside of the right sleeve, midway between the wrist and elbow until 1947 when it was shifted to above the left breast pocket. In 1943 the Uniform Regulations were modified to allow enlisted men, who were qualified for submarine duty then subsequently promoted to commissioned or warrant ranks, to continue wearing the enlisted submarine insignia until they qualified as submarine officers when they were entitled to wear the officers submarine pin.
A 1950 change to Uniform Regulations authorized the embroidered insignia for officers (in addition to pin-on insignia) and a bronze, silver plated, pin-on insignia for enlisted men (in addition to the embroidered device).