The Coast Guard is involved in the search for two missing boaters in Louisiana's Lake Pontchartrain this afternoon after their small boat was located overturned in the lake Monday afternoon. Coast Guard rescue boat and helicopter crews are searching for Frank Andrew and Gretchen Life, both of Gretna, La. The Causeway Police initially located the boat, a homemade vessel of about 20 feet, near the Causeway Bridge Monday and notified the Coast Guard at about 2:30 p.m. A Coast Guard Station New Orleans smallboat crew was immediately launched to investigate the report and conduct an initial search. The crew obtained the registration number from the vessel, but lacking any correlating information such as a mayday call, flare sighting, or overdue report, returned to base.