Aluminum boats using welded marine alloy construction are strong, lightweight, durable, and easy to maintain. as with steel, the designs should be specifically intended for this material. plans listed for aluminum construction include all the details necessary to build the boat in sheet aluminum.. Cope aluminum boat designs, proven plans for high quality welded aluminum boats.. A large number of aluminum single hull (monohull) boat designs (plans) that serve a variety of purposes. these include orcas, outbacks, sitkas, sportsters, sport fishers, crew boats, crab boats, dive boats, and patrol boats..