His heroic spirit has set sail.

A Long Island Navy SEAL who was killed in combat in Afghanistan was memorialized in Bath, Maine, yesterday with the christening of a ship in his name.

The Navy guided-missile destroyer was bestowed with the name Lt. Michael Murphy during a somber ceremony yesterday.

The Patchogue native was gunned down June 28, 2005, while searching for a Taliban leader near Asadabad.

Murphy’s mother, Maureen, christened the massive ship on what would have been his 35th birthday.

“Happy birthday, Baby,” she said before smashing a bottle of champagne against the $1.1 billion ship destined for Hawaii.

Murphy, then 29, was killed when he left cover to radio for help for his men during a firefight with the Taliban.