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Fitzpatrick admits that diesel-elec- tric drives are signiÞ cantly more ex- pensive than conventional propulsion systems and create a more complex vessel which requires maintenance from a higher level or personnel, but he said they nonetheless provide the best technical option, especially when considering in the riverÕs geography and operational requirements. ÒWith a conventional propeller boat, espe- cially running on heavy fuel, going full ahead to full astern, thereÕs a very high chance, with the propellers being reversible, of overloading the engines and stalling the ship, which would be an absolute disaster if they tried to do a crash stop.Ó Another challenge presented by the river system is its enormous amount of debris, especially when running azimuth drives, which Fitzpatrick said has led to the installation of propel- lers, nozzles and gear boxes in the drive that are Òessentially ice-class.Ó The electric propulsion system would then offer another beneÞ t as an over- load would be passed to the main gen-erator. Three main diesel generators sets provide 3 x 1,710 ekW of power to 3 x 1,600 kW motors, each driving a Schottel SRP 1215 Z-drive with noz- zle custom-modiÞ ed for shallow draft hull form. The nozzle is ß attened on the bottom to reduce draft and suc- tion, while the upper part of the noz- zle is designed to match the shape of the tunnel for better embedment into the hull, which reduces draft by an- other foot. The major electric compo- nents, such as AFE drives, propulsion motors, generators, etc., are of ABB design and supplied by Elkon, while the generator engines are three W?rt- sil? 9L20, medium speed engines, each producing 1,800 bkW at 1,000 rpm.www.marinelink.com MN 29MN April14 Layout 18-31.indd 29MN April14 Layout 18-31.indd 293/21/2014 10:04:54 AM3/21/2014 10:04:54 AM
