REDUCTION IN PROPELLER DIAMETER LEADING TO SATISFACTORY PERFORMANCE :
This case study relates to the ship delivered by ONOMICHI shipyard to MMS-TOKYO company on 25th January, 2006.
One of the VLCCS, having main Engine Mitsui- MAN B&W – 8S80 MC with 34850 BHP x 70 RPM and propeller diameter 10.8m was seheduled for sea trial for 5 days. Entire programme was handed over to the ship’s staff and trial started.
On the 1st day of trail, everything was normal 2nd day also apparently it seemed things are going quite well but later in the evening, Japanese people those were representing the yard, called the ship’s staff for a meeting & ship’s staff were told that vessel is not achieving required speed (Normal service speed). Further trial was suspended & the ship was taken back to yard.
Very next day, a meeting was held in the yard. It was decided to cut the propeller blades all round, i.e. to reduce the dia of blade from 10.8 to 10.4 m. -- To carry out this job it took some 24 hrs, subsequent seal trial result was very satisfactory.