Marine Log - January 2008 - (Page 16) FERRIES Figure 2. Machinery equipment investment costs ICE CLASS TANKERS MACHINERY COMPARISONS Wärtsilä compared the different machinery options based on: Weight The CRP machinery option shows an advantage when it comes to weight. Even with the low speed engine, the weight is at the same level as with conventional twin shaft machinery. Power demand and fuel consumption The power demand of the vessel has been calculated and compared with results from 50 previous CRP model tests that Wärtsilä has been involved in. The delivered power demand of the CRP propulsion is about 9.5-11% lower than that of the twin-screw option. The larger saving is achieved with the option having the lower Wärtsilä 46 medium-speed engines, as their weight is 400 tons less, due to the lighter machinery and the small ship. However, fuel consumption also depends on the transmission losses, as well as the specific fuel oil consumption in each operating mode. The mechanical thruster has higher transmission losses than a conventional shaft line owing to the two bevel gears. On the the conventional twin shaft ferry and still offer the same cargo capacity. There is some reduction in lane meters by way of the thruster engine compartment. However, this is compensated by a larger lower cargo hold made possible by the shorter engine room. The CRP machin- ery option with a high main engine going through the main deck, and with the ramp above the machinery, cannot offer the same cargo capacity, unless the length of the ship is increased. SERIOUS AIR FOR SERIOUS PLACES Confined Space Air Ventilators 8”, 12” & 20” Models Portable Lightweight 848-8000 CFM, 110/220V 12V DC Pneumatic Americ Corporation 785 Bonnie Lane Elk Grove Village, IL 60007 For more information, call 800-364-4642 or Fax 847-364-4695 www.americ.com 16 MARINE LOG JANUARY 2008 www.marinelog.com http://www.greatamericaninsurance.com http://www.greatamericaninsurance.com http://www.americ.com http://www.americ.com http://www.marinelog.com
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