Another source on sloops is the web site of the Hudson River Maritime Museum.

http://www.ulster.net/~hrmm/

In addition to information available on the site, it allows you to order books, such as:

Paul E. Fontenoy, "The Sloops of the Hudson River: A Historical and Design Survey" (Mystic Conn.: Mystic Seaport Museum in association with the Hudson River Maritime Museum, 1994).