INITIAL COST => ( Carbon steel X 10 )
Perhaps the oldest copper-nickel boat in existence, the Asperida is still in fine shape
Nickel Magazine, March 2005 -- Designers of boats need to consider many things when choosing materials for the hull of their ocean-going vessels – for example: ensuring the surface is smooth so that the vessel can move through the water with little resistance, keeping the weight to a minimum, and ease of maintenance. Attending to these design considerations improves the availability of the boat and lowers operating and maintenance costs, as Dr. Kenneth W. Coons has learned.
Coons, who was professor of chemical engineering at the University of Alabama in the late 1990s, is an avid yachtsman, who owned vessels made of wood, steel, aluminum and fibreglass. But he was dissatisfied with them all and so spent decades evaluating alternative materials. One technique he used was to tow sample coupons behind his yacht and then examined their resistance to corrosion. Based on these evaluations, he decided in 1966 to build a yacht made of copper-nickel alloy C71500, which contains 29-33% nickel.
Today’s boat designers should be thankful that he made that decision because it allows today’s designers to use this material with confidence.
Coons’ yacht was designed by S. M. van der Meere and built in northern Holland in 1967 by Trewes International. The method of construction was almost identical to that used for carbon steel. However, welders had to be trained, and some welds (in W60715, containing 29% nickel) had to be redone. The hull was painted above the waterline for aesthetics. The hull plates were just 4 millimetres (mm) thick.
Although the initial cost of the hull was ten times that of a boat made of carbon steel, annual maintenance costs were so low that the savings paid for the higher initial cost in just five years.
After being sold five times, the Asperida landed in the hands of its present owners Waldemar Cieniewicz and Anna Muriglan. The duo sailed the ship to New Jersey in 2004, where it was refurbished and refitted. The average thickness of the hull was 3.86 and 3.96 mm (close to the original thickness), based on measurements by the Copper Development Association.
"Clearly, C71500 should be considered seriously as a hull material, not only for pleasure boats but also for commercial and military vessels," says Harold Michels, vice-president, technical and information services for Copper Development Association.