Propeller Retrofits Saves 10 Percent Fuel

Benefits of fitting CLT propellers include fuel savings of around 10 percent while maintaining the same speed, according to Geneva-based shipowner Cargill International SA, which has recently released consumption figures for two of its Panamax bulk carriers. The 70,000 dwt Powhatan and Paiute had CLT propellers retrofitted in February and March 1998, after Cargill had already benefited from more than two years' first-hand experience of the CLT propeller concept developed by Madrid-based designer Sistemar. Cargill first fitted a CLT propeller to one of its vessels in 1995, the 13,600 dwt orange juice carrier Bebedouro, and subsequently to two Capesize bulk carriers, the 164,000 dwt Cherokee and Comanche, as well as Powhatan and Paiute. "The payback period for the CLT propeller investment for the five ships has been approximately two years per installation," says Hans-J Hollstein, technical manager of Cargill International's Ocean Transportation Division. Powhatan and Paiute are being offered on the time-charter market with daily fuel consumptions of 27.5 tons for a speed of 15 knots in ballast, and 28 tons for a 14-knot service speed when fully loaded. These figures represent 8.3 percent and 10.25 percent improvements respectively over characteristics offered for their sister ships Peoria and Pequot, which are fitted with conventional propellers (30.0 tons/day in ballast; 31.2 tons loaded, at the same speeds). Mr. Hollstein adds that, as well as the direct fuel cost benefits, the vessels with the lower fuel consumption because of their CLT propellers are much more attractive on the market, especially when freight rates are low. For the Capesize bulkers Cherokee and Comanche, Cargill says that as a result of fitting the CLT propellers the daily fuel consumption has been reduced from 58.5 tons/day to 52.5 tons fully laden, and from 54.4 tons/day to 49.5 tons in ballast. The main reason for Bebedouro's retrofit was to reduce propeller-excited vibration levels, with fuel saving being an additional benefit. Since then Cargill has experienced a nine percent improvement in fuel consumption.