Segundo

The second-in-command of a large party or company
Found on http://www.xmission.com/~drudy/amm/gloss.html

Segundo

USS Segundo was an American Balao Class submarine of 1525 tons displacement launched in 1944. USS Segundo was powered by diesel engines providing a top speed of 21 knots, carried a complement of 75 and was armed with one 4-inch gun, two 20 mm Oerlikon anti-aircraft guns; six 21 inch bow torpedo tubes and four 21 inch stern torpedo tubes.
Found on http://www.probertencyclopaedia.com/browse/RS.HTM
No exact match found