Effects for reduction of roll motion by the control of steering gear

Reduction of ship ′s rolling is the most important performance requirement for improving the safety of thecrew on board and preventing damage to cargo as well as improving the comfort of the ride . It is acommonexperience for mariners , to see that steering with a rudder generally induces rolling of the ship , though theoriginal aim of the rudder is to keep the ship ′s heading to the required course . At the first stage , when arudder is steered , usually aship heels in an inward direction , due to the roll moment acting on the rudder . Atthe next stage in steering , the main heel may change to an outward . This coupling between rudder and rollmotion has become an attractive problem from the point of view of roll stabilization using the rudder ,because it is a natural in sight that if the rudder action is skillfully related to the change of roll as well as tothe course deviation , the roll can be reduced to acertain degree . The main aim of this paper is to discuss theresults of the actual full-scale sea trials carried out on steer gear No .1 and No .1 ·2, the individual quarter -master and to make clear their statistical properties , using the actual data which included measurement ofroll angle , roll rate and the comparative tests were carried out immediately after each other , in order tominimize any statistical variation in sea conditions . It can be concluded that the steer gear No . 1 ·2 reducedthe roll motion on average by about 21% in comparison with the No .1 and confirmed the some difference asper aability of quarter -master ′smaneuver .Keywords: Roll stabilization reduction , Steering gear , Rudder , Roll angle , quarter -master ′smaneuver