After graduating from
Harvard, he speculated in real estate before signing on as a draftsman with John R. Purdon, a respected yacht designer in Boston with several
knockabout designs to his credit. Crowninshield struck out on his own 18 months later, starting a yacht design and brokerage firm which quickly prospered. He would rise to become one of America's most respected yacht designers during a period which is now regarded as the golden age of American wooden yacht design. He designed the schooner
Adventuress, which was launched in 1913 and has been named a
National Historic Landmark. Crowninshield is now best remembered for his working schooners and his
America's Cup contender
Independence (George Lawley & Son shipyard, 1901) for
Thomas W. Lawson. He was also responsible for designing the iconic Dark Harbor 12 1/2 and
17 1/2 sloops. He served as president and general manager of Crowninshield Shipbuilding Company of Fall River, Massachusetts from 1917 to 1926. The shipyard built the "
Six-Bitters"
CG-130 through
CG-139 for the
United States Coast Guard (
CG-133 would later serve as
USS YP-45 during
World War II). He designed the unique seven masted schooner
Thomas W. Lawson, named for his patron. ==Personal life==