Standard manoeuvres and associated terminology are as defined
below:
.1 The test speed (V) used in the Standards is
a speed of at least 90% of the ship's speed corresponding to 85% of
the maximum engine output.
.2 Turning circle manoeuvre is the manoeuvre to
be performed to both starboard and port with 35° rudder angle
or the maximum rudder angle permissible at the test speed, following
a steady approach with zero yaw rate.
.3 Advance is the distance travelled in the direction
of the original course by the midship point of a ship from the position
at which the rudder order is given to the position at which the heading
has changed 90° from the original course.
.4 Tactical diameter is the distance travelled
by the midship point of a ship from the position at which the rudder
order is given to the position at which the heading has changed 180°
from the original course. It is measured in a direction perpendicular
to the original heading of the ship.
.5 Zig-zag test is the manoeuvre where a known
amount of helm is applied alternately to either side when a known
heading deviation from the original heading is reached.
.6 The 10°/10° zig-zag test is performed
by turning the rudder alternately by 10° to either side following
a heading deviation of 10° from the original heading in accordance
with the following procedure:
-
.1 after a steady approach with zero yaw rate,
the rudder is put over to 10° to starboard or port (first execute);
-
.2 when the heading has changed to 10° off
the original heading, the rudder is reversed to 10° to port or
starboard (second execute); and
-
.3 after the rudder has been turned to port/starboard,
the ship will continue turning in the original direction with decreasing
turning rate. In response to the rudder, the ship should then turn
to port/starboard. When the ship has reached a heading of 10°
to port/starboard of the original course the rudder is again reversed
to 10° to starboard/port (third execute).
.7 The first overshoot angle is the additional
heading deviation experienced in the zig-zag test following the second
execute.
.8 The second overshoot angle is the additional
heading deviation experienced in the zig-zag test following the third
execute.
.9 The 20°/20° zig-zag test is performed
using the procedure given in paragraph 4.2.6 above using 20° rudder
angles and 20° change of heading, instead of 10° rudder angles
and 10° change of heading, respectively.
.10 Full astern stopping test determines the track
reach of a ship from the time an order for full astern is given until
the ship stops in the water.
.11 Track reach is the distance along the path
described by the midship point of a ship measured from the position
at which an order for full astern is given to the position at which
the ship stops in the water.