The ATC was a modified LCM-6 landing craft.  It was 56 feet long by 14 feet wide and was powered by two diesel engines driving twin propellers.  All versions carried a chain minesweeping dragline for cutting cables of command-detonated mines in canals.  The ATC had an armored superstructure that had gun tubs for .50 machine guns, 20mm cannon, or 40mm automatic grenade launchers.  Early ATCs [Program 4] were called “rag tops” due to the fabric cover over the well deck of the boat.  Later boats replaced the soft top with a hard top [Program 5] capable of landing a UH-1 helicopter.  Called the ATC(H) for helicopter, some of these boats were pressed into service as a battalion aid station with doctors and medics to take care of wounded sailors and soldiers.