In July 1846, a battered and storm-tossed hulk, the William Penn, was moored at the pier at Light Street wharf across from what is now the McCormick building. A ship chandler, a rigger and other local merchants with interests in the shipping industry bought the ship and converted it into a place of worship for sailors visiting the port of Baltimore.
The "Ship-Church" was ready for service after being fitted with a pulpit and benches holding 600 people. A large roof was built over the decks with 24 windows to let in sea breezes and sunlight. Samuel Kramer, the former skipper of the ship, was appointed minister.
The floating church was condemned in 1852. The congregation built a new church on Lee Street and called it Sailors City Bethel. After several years at that location and a brief stay at a church on Hill Street near Charles, the congregation built the present structure in 1873. In 1881, the name was changed to Sailors Union Bethel Methodist Church.
A model of the William Penn which hangs from the ceiling of the sancutary commemorates the church's origins as a "Floating Bethel" serving the travelers of the sea.