Significant improvement in the fuel efficiency of three 32.5k dwt bulk carriers
A recent cooperation between Stone Marine Propulsion and the Danish Shipowner D/S Norden A.S. has resulted in a significant improvement in the fuel efficiency of three 32.5k dwt bulk carriers contracted from the Jiangmen Nanyang Shipyard. The ships being the last of a series order for identical vessels.
Switching to a slower turning main engine presented one opportunity to improve fuel consumption but, in order to maximise the potential improvement the vessels have been fitted with Stone Marine Propulsion’s new high efficiency NPT propeller. This project was first reported in a presentation given at the Maritime Propulsion Conference held in London during March 2011, and the first results have now become available.
Due to main engine delivery schedules the first of the three ships retained the original machinery configuration but was fitted with an NPT propeller. This provided the ideal opportunity to obtain full scale performance results comparing previous ships in the class fitted with the original machinery and propeller, to one fitted with an NPT propeller.
Sea trial results have been very encouraging. During project planning the gain from the NPT design was conservatively assessed at 3%, however the shipyard’s trial reports show a much larger than expected improvement – approximately 6%. While it is possible that other factors, such as differences in hull condition and measurement accuracy have influenced the trial results, it is also reasonable to say that the expected gain in efficiency has been achieved, and probably exceeded.
The ship’s owner will be monitoring the long term performance of the ships in service to confirm the results, and the trial results for the first of the class with the slower turning main engine and NPT propeller should be available shortly. They are awaited with considerable interest.
Source: Stone Marine Propulsion