Big Motor Problems john.denham Total Views: 68 August 19, 2009 Big Motor Problems By John G. Denham I am impressed with the significant improvements that large diesel engine manufacturers are making in reducing offensive emissions, improving operational efficiency and cutting costs. When the “Firecracker Engineers” put their mind to it, it happens. Government is putting a lot of pressure on engine exhausts; the bigger the engine the more political pressure. Owners want more speed and efficiency and less cost. I have not observed any government involvement except to increase standards. The diesel engine manufacturing guys have addressed faster, more powerful, cleaner, efficient and less costly engines admirably, but there is another problem that effects operations: minimum speed. The minimum speed limitation is an operational safety factor when maneuvering in confined, congested and special maneuvering areas. Rule 6 of the International and Inland Rules: “Every vessel shall at all times proceed at a safe speed…” A gold mine for maritime lawyers. The Pacific Maritime Magazine May 2008 issue’s feature article “Large Marine Diesel Engines” exemplified: “APL recently ordered eight MAN B&W 14K98ME-C7 two stroke low-speed crosshead engines …will generate 115,000 bhp at 105 RPM …to be installed in eight new 10,000 teu container ships.” As advertised the operating range of similar behemoths maybe as low 45 RPM and as high as 120 RPM. With direct drive and an efficient propeller the probable minimum speed may be 5.0 knots. Persons piloting such vessels may need to stop and start the engines any number of times due to circumstances; the engines are usually started with compressed air. Therefore knowing the quantity of consecutive start and stops is essential as an operating factor. There are two navigation considerations that must be resolved while en route: the safe speed of advance and the hydrodynamic effect of the vessel’s movement; the greater the speed the greater th