The Collaborative International Dictionary of English v.0.48:

Steersman \Steers"man\ (st[=e]rz"man), n.; pl. Steersmen
   (st[=e]rz"men). [Steer a rudder + man: cf. AS. ste['o]rmann.]
   One who steers; the helmsman of a vessel. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

steersman
    n 1: the person who steers a ship [syn: helmsman, steersman,
         steerer]