An Eastham Fire Marine Unit responded, along with the Wellfleet Harbormaster around 1:30 p.m after getting reports of 2 people in distress from someone at Cooks Brook in Eastham.
When rescue crews arrived they found the catamaran partially sunk and the father and son were in the water with life preservers.
The two were pulled out of the water and taken to shore where they were evaluated for hypothermia but refused further treatment.
The Wellfleet Harbormaster and Wellfleet Fire Department secured the catamaran as close to shore as possible.
The two men rescued said that they were in the water for an hour and a half and that one of the vessels hulls started taking on water for an unknown reason.