The site of the Navy Yard, Philadelphia, Pa., at the junction of the Schlylkill and Delaware Rivers.
(YFB-20: t. 425; l. 136'6"; b. 29'; dr. 8'9"; cpl. 20)
Block Island (ex-Hook Mountain, ex-Machigonne) was built in April 1907 by Neafie & Levy S. and E. B. Co., Philadelphia, Pa.; purchased by the Navy 24 February 1941 from H. Reynolds Palmer and Raymond H. Abell, Gales Ferry, Conn.; classified YFB-20 27 February 1941; renamed and placed in service 7 March 1941.
League Island (YFB-20) was assigned to the 4th Naval District 17 March 1941 for ferrying service between the Naval Yard, Philadelphia, Pa., and National Park, N.J., which she carried out efficiently throughout the war. League Island was placed out of service 6 June 1946 and returned to WSA 9 January 1947.