Shipmaster (kubernētēs). Old word (from kubernaō, to steer), helmsman, sailing-master, in N.T. only here and Act 27:11. Subordinate to the nauklēros (supreme commander).
That saileth any whither (ho epi topon pleōn). “The one sailing to a place.” See Act 27:2, tous kata tēn Asian pleontas (those sailing down along Asia). Nestle suggests ponton (sea) here for topon (place), but it makes sense as it is.
Mariners (nautai). Old word (from naus, ship), in N.T. only here and Act 27:27, Act 27:30.
Gain their living by the sea (tēn thalassan ergazontai). “Work the sea.” This idiom is as old as Hesiod for sailors, fishermen, etc. See Rev 18:10, Rev 18:15.