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Naval Architecture & Marine Engineering Demystifying Parametric Roll An ABS research project deflates the mystique surrounding parametric roll, a rare but dangerous phenomenon partic- ularly threatening to containers/lips. In October 1998, a large, post- Panamax containership limped into the port of Seattle, a victim of the largest ever loss of containers while on passage. On its voyage from Kaohsiung, Taiwan, the ship had encountered a terrible storm that for some 12 hours lashed the vessel with high winds and boarding waves reaching as high as the foremast and the running lights on the bridge. The offi- Full Service Shipyards New Construction Repair and Conversions Atlantic Marine, Inc. Atlantic Dry Dock Corp. 8500 Heckscher Drive Jacksonville, FL 32226 (904) 251-1545 Atlantic Marine - Mobile Alabama Shipyard Post Office Box 3202 Mobile, AL 36652 (251) 690-7100 www.atlanticmarine.com Our new executive team: (Seated) Greg Guarisco, Mobile and Kevin E. Wilson, Jacksonville; (Standing) Tom Williams, Mobile and Chuck Nugent, Jacksonville The mission of Atlantic Marine is to provide our customers with quality work- manship, on-time delivery and customer-friendly service in both ship new con- struction and ship repair. We have assembled at our yards in both Jacksonville and Mobile a highly-qualified team of experienced, knowledgeable and motivated exec- utives who share our company's commitment to excellence. Greg Guarisco is Vice President, Sales & Marketing for Atlantic Marine-Mobile and Alabama Shipyard. Greg has over 25 years maritime experience in production, estimating and sales in both repair and new construction divisions. He has been with Atlantic Manne for over 15 years. In Jacksonville, Kevin E. Wilson has been promoted to Vice President, Sales & Marketing for both the Atlantic Marine new construction division as well as the Atlantic Dry Dock Corp. ship repair facility. Kevin has been with the company for over 18 years and has more than 28 years of maritime experience in various man- agement positions including production, estimating and planning. Tom Williams is Vice President of Operations for both ship repair and new construction at Mobile. With over 30 years of marine operational and maintenance experience, Tom joined Atlantic Marine in 2002. He has a Degree in Mechanical Engineering and a Masters in Telecommunications Systems-Management. Charles (Chuck) Nugent, was recently named Vice President of Production for the Atlantic Marine new construction division in Jacksonville. Chuck has been with Atlantic Marine for over seven years and has 31 years experience in new construc- tion and ship repair operations. See us at the Int'l WorkBoat Show Booth 1543 Circle 210 on Reader Service Card 22 Maritime Reporter & Engineering News cers not only saw green water at bridge level, but also had to watch helplessly as the forward container stacks collapsed. By the time those violent seas finally passed, the ship had lost a third of its 1,300 containers on deck; another third lay wrecked and scattered about, with smashed containers and contents hang- ing over both sides of the ship. Despite the best efforts of the ship's well-trained, professional crew, the ves- sel suffered strangely severe motions, unusual even for such storm conditions that made control nearly impossible at times. Yaw angles reached 20 degrees port and starboard, and severe rolling of up to 40 degrees combined with extreme pitching left the master without effective control of the vessel. It was, in fact, in the grip of the phenomenon known as parametric roll resonance or, simply, parametric roll. Parametric roll is one of those destructive phenomena that depend on a set of coincidences so fine- ly balanced as to make the occurrence seem nearly impossible: the ship's geometry has to have certain characteristics; its length has to be compara- ble to the wave-
