半滑走型高速船の操縦性能

Abstract

In this paper, the effects of hull attitude change, ship speed, metacentric height GM and stern appendages such as rudder, shaft bracket, bossing and propeller shaft on maneuverability of a high speed vessel are investigated. Range of Froude number of the studied ship is from 0.6 to 1.0. The hydrodynamic force characteristics are captured by a Circular Motion Test in Hiroshima University Towing Tank. Using the hydrodynamic derivatives, maneuverability indices are calculated. As a result, the following knowledge is obtained through the study: by inclusion of ship attitude change, Y'υ increases, N'r slightly decreases, Y'r -m'x and N'υ significantly increase. The effect of the attitude change is not negligible. Inclusion of the attitude change improves the course stability due to contribution of Y'r and -m'x and N'υ. When ship speed increases and GM decreases, the course stability becomes worse in general although the turning performance is improved. This tendency is the same for displacement typed ships. The bare hull ship becomes unstable for course keeping in any Froude numbers, although the ship with stern appendages is stable. Thus, the effect of stern appendages on the course stability is considerably large. This is mainly due to the increase of absolute values of Y'υ and N'r by the stern appendages.