Gunboat
US riverine gunboats in the Vietnam War, included Patrol Boats River (PBR), constructed of fiberglass; Patrol Craft Fast (PCF), commonly known as Swift Boats, built of aluminum; and Assault Support Patrol Boats (ASPB) built of steel. U.S. Coast Guard 82-foot s supplemented these US Navy vessels. The ASPBs were commonly referred to as "Alpha" boats and primarily carried out mine-sweeping duties along the waterways, due to their all-steel construction. The ASPBs were the only US Navy riverine craft specifically designed and built for the Vietnam War. All of these boats were assigned to the US Navy's "Brownwater Navy".