Zig-Zag Manoeuvre

You can calculate the zig-zag manoeuvre at any required speed for a certain rudder command and a certain check angle. For small motion, the ship manoeuvring equation can be represented by Nomoto's Ref. [] first order differential equation

where represents the quick response and the directional stability index. represents the turning ability index, is the yaw rate and is the rudder angle.

The zig-zag manoeuvre data is analyzed to find out the values of the and indices. The non-dimensional values of and are defined by:

where L is the ship length and V is the ship approach speed.

The following differences arise between the two ship types:

Merchant

Shallow or deep water.

Conventional rudder type only.

Naval

Deep water only.

Choice of conventional, Becker or Schilling rudders.

The program will calculate the propulsion point, followed by the zig-zag manoeuvre data. The maximum time for the simulation of the zig-zag manoeuvre has been set at 3000 seconds, so you must choose a ship speed, rudder command angle and check angle to ensure that the manoeuvre is performed within the allowable limits. hows the main data of the zig-zag manoeuvre:

Figure 3:13. Main Data of the Zig-Zag Manoeuvre