On the Course Stability of Ship under the Manual Steering

Abstract

Manual steering is assumed to be written analytically in the following Laplace transform,
δ^* (s) =-K^*_p (1+T^*_Ds+T^*_I/s) θ (s).
δ^* (s) is the angle of rudder given by a quartermaster, θ (s) is the angle between ships head and the desired course, and K^*_p, T^*_D, T^*_I are proportional constants.
In the practical point of view it is advantageous to adopt the approximated form of equation of ship motion
Tdθ/dt+θ=Kδ,
which has been proposed by K. Nomoto. This simplified equation can give directly the characteristics of ship motion under manual steering.
According to the above two equations, the author has pointed out the possibility of finding the optimum value of ship maneuverability.