Within our cemeteries, it is common to find among different symbols objects that may reflect either the profession of the buried person, or act as a reference to their affiliations or membership (i.e. Freemasonry). They may also represent their hobbies, leisure or fields of interest.
In that sense, a ship or boat may often remind and symbolize the life of a sailor, and therefore may be found on sailor’s graves.
But the ship was also an ancient Christian symbol. It represents the Church tossed on the sea of disbelief, worldliness, and persecution but finally reaching safe harbour with its cargo of human souls. Part of the imagery comes from the ark saving Noah's family during the Flood (1 Peter 3:20-21). Jesus protecting the Peter's boat and the apostles on the stormy Sea of Galilee (Mark 4:35-41). It was also a great symbol during times when Christians needed to disguise the cross, since the ship's mast (or anchor) forms a cross in many of its depictions.