The bodies of Steven James, 53, of Marshfield, Mass., and Robert Becher, 55, of Cromwell, Conn., were found on the shore of the Westport River about 2 1/2 hours after a local resident spotted their overturned boat and notified authorities, the Boston Globe reported.
A third man, Gregg Angell, 51, of Westport, Mass., was found about 30 minutes later by a U.S. Coast Guard helicopter crew on a small island in the middle of the river.
He was treated for hypothermia and was listed in fair condition at a Rhode Island hospital.
The air temperature was 8 degrees at the time of the rescue, while the water temperature was 35 degrees.
Richard Earle, Westport's harbormaster, said a strong wind blowing against the tide in the middle of the river had created 3-foot waves.
Authorities said the incident did not appear suspicious.
James ran the Monster Shark Tournament on Martha's Vineyard for more than 20 years, said Peter Martell, owner of the Wesley Hotel, which served as headquarters for the event.