Yaw Stability of Ships - Basic Principles

Yaw Stability is an important element of Ships Manoeuvrability - both for course keeping and turning ability. This first video in a series explains the Basic Principles of stability in steady state equilibrium conditions and the forces / moments involved. The role of the unstable moment due to drift angel and the stabilising damping moment due to rate of turn in the yawing motion will be discussed. Definitions of yaw stability during turning motion and on straight motion will be given. Samples of stable and unstable ship behaviour will be shown by Fast Time Simulation using the SAMMON Planning tool.
The next videos will demonstrate manoeuvres (e.g. Spiral Test, Pull-out Test and Zig-Zag Test) to identify and discuss the stability condition for ships and the different aspects contributing to yaw stability.