One interpretation of the “three ships” in the English carol is that they symbolized the camels, the “ships of the desert” presumably used by the Magi.
Bethlehem is clearly not a port, and I think we do well to respect the symbolism and artistry no matter the genre of music:
O they sailed into Bethlehem,
On Christmas day, on Christmas day;
O they sailed into Bethlehem,
On Christmas day in the morning.
Image credit: By J. Patrick Fischer – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=17859427
Catholic Sensibility 