After departing from runway 08, the CV-240 climbed to 400 feet agl where the left engine lost power. After confirming a loss of power, the pilot feathered the left propeller, and called for maximum “dry” thrust on the right engine. Wet power was available which would have provided 450 additional horsepower, however, the pilot elected not to use it. The airplane was unable to maintain altitude, collided with a palm tree, and came to rest on the beach in the surf line. The reason for the left engine malfunction was not determined due to salt water damage. The airplane was 600 pounds over maximum weight. PROBABLE CAUSE: “A loss of engine power for undetermined reasons, the pilot’s improper emergency procedure after the power loss, and the overloading of the airplane, resulting in an inability to maintain altitude and terrain clearance.”