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is fitted with the full appendages , a self-propulsion and steering system . As it moves steadily the rudder is deflected to the starboard ( or port ) and when the desired change of the ship ’ s course of 20 o is attained the rudder is then deflected to 40 o on the opposite side ( 20 o to the port of the ship ’ s centreline ) and the model is allowed to turn as shown .
As soon as the model has turned 270 o i . e . as it starts to move in opposite direction of the original direction , the propulsion system is switched off and the rudder is brought back to the centreline forward and aft and the model is again allowed to move in a straight line course . The test is repeated for different rudder deflections and speeds .
The measurements recorded during the test are the ship ’ s course and speed at suitable intervals of time , initial speed , final speed , propulsion motor output , propeller revolution per minute , propeller pitch and also the following :
● Time taken to deflect rudder to 20 o
The characteristics determined by all the tests discussed above are very important in navigating and steering ships in open seas , restricted waterways and ports by the captain or harbour pilot .
● Time to attain the desired course of 20 o .
● Time taken to deflect rudder to 40 o .
● Time to attain the desired course of 270 o .
● The distanced travelled A when the model has turned to 270 o and moves in the opposite direction to the initial course .
● The distance advanced B .
● The separation distance from the original path C .
The model track during the test can be plotted based on the data of the ship ’ s course at intervals of time recorded to obtain a curve . The times taken to attain the required model ship ’ s course and rudder angles are known and the distances A , B and C are subsequently determined . Therefore the ship ’ s characteristics for certain conditions of rudder angle and speed are known by performing the test .
CONCLUSION
The characteristics determined by all the tests discussed above are very important in navigating and steering ships in open seas , restricted waterways and ports by the captain or harbour pilot .
REFERENCE
Development in Ship Manoeuvrability by R . K . Burcher , RINA , April 1971 . Modern Ship Design by Thomas C Gillmer , Naval Press Institute , 1977 . Seakeeping Tests of a 70m Offshore Patrol Vessel by Netherland Ship Model Basin ( MARIN ), 1983 . Principal of Naval Architecture , Volume 2 by Edward V Lewis , SNAME , 1988 . Resistance , Propulsion and Seakeeping Experiments on a Twin Screw 85m Corvette by British Maritime Technology Limited , Teddington , England , 1992 . International Maritime Organisation Resolution A . 751 ( 18 ), Interim Standards for Ship Manoeuvrability , Adopted on 4 November 1993 . Model Tests of Hydrographic Survey Vessel , by Shiffbau-Versuchsaustalt GmbH , Potsdam , Germany , 1995 . International Maritime Organisation Resolution MSC . 137 ( 76 ) Adopted on 4 December 2002 Standards for Ship Manoeuvrability . American Bureau of Shipping ( ABS ), Guide for Vessel Manoeuvrability , March 2006 . Hull Form Study for DSME Training Vessel ( Propeller Design ), Korea Ocean Research & Development Institute ( KORDI ), May 2012 . DSME Training Vessel Seakeeping Tests , SSPA Report RE30105754-02-00A , May 2012 DSME Training Vessel Manoeuvring Tests , SSPA Report RE30105754-03-00A , May 2012 .
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