RedactedNarrative: Due to a strong storm approaching, the Operator of Vessel 1 decided to anchor Vessel 1 and ride out the storm on the lake.  The Operator deployed the anchor and tied off the line to the cleat near the transom of Vessel 1.  The Operator then observed that waves were breaking over the back of Vessel 1 and filling Vessel 1 with water.  The Operator then tried to untie and cut the line, but was unable to do so before Vessel 1 filled with water and swamped.  The Operator and additional Occupant aboard Vessel 1 were both in the water for approximately 1.5 hours before being rescued by other boaters in the area.