Ship/Boat
Ship: Ships are generally larger than boats, but share many of the same meanings. They can be solar or lunar, carrying these two celestial bodies across the seas. With their close connection to water, ships often bear significance as fertility symbols, and are linked to the Great Mother. The Christian church is sometimes referred to as a ship or the ark, with the mast of the ship being the cross. Information taken from: Online Symbolism Dictionary
Boat: ...apprehended as the means of transition from the material to the spirit world. Symbolic cradles for the souls of those to be reborn, boats cross the perilous regions of the underworld or are cast adrift with the bodies of chiefs. In Greek myth, a boat powered by the ferryman Charon, carries dead souls across the River Styx into the underworld. From: Dictionary of Symbols (Tresidder)
Songs referenced:
1,000 Oceans