||The paper presents new results on the inherent properties of ship linear dynamics. The focus is
made on the second‐order formulation for the uncoupled equations of sway and yaw, and on their unique,
unknown performance within the zigzag test. From the standpoint of application to full‐mission model
tuning, a very important loop in the drift‐yaw domain of the zigzag behaviour, as governed by the rudder rate
dependent time constants (of T3‐type), is brought to the light. This and some other dependent effects, like
overshoot angle performance, are likely to be lost, if the well‐known, rather ambiguous, first‐order
approximations are deployed.