The words were written c.1860 by William Whiting, master of Winchester College Choristers' School, and the melody by John Bacchus Dykes, a clergyman. Neither seems to have had any obvious seafaring connections, though Dykes was born in Hull. Of course, there can't be that many people in England who don't have maritime connections somewhere in the family, so it is (or at least, was) an ever-present concern.