This boathouse is the home of the Wentworth Rowing Club, whose shells may be seen to the left of the building. This site is also used for community boating activities.
The boathouse is named for Blessing of the Bay, the second oceangoing, non-fishing vessel built in what is now the United States. The ship was completed in 1631, very close to this spot.
http://en.wikipedia.org/wiki/Blessing_of_the_Bay