4.1 Geometry of the ship4.1.1 Length (L)
is the length measured between the aft and forward perpendiculars.
is the point on the centreline of a ship midway between the aft and forward
4.1.3Draught (Ta )
is the draught at the aft perpendicular.
4.1.4Draught (Tf )
is the draught at the forward perpendicular.
4.1.5Mean draught (Tm )
is defined as Tm
is defined as τ = (Ta
is the full load displacement of the ship (tonnes).
4.2 Standard manoeuvres and associated terminology
Standard manoeuvres and associated terminology are as defined below:
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.
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.
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.
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.
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.
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:
after a steady approach with zero yaw rate, the rudder is put over to 10° to
starboard or port (first execute);
when the heading has changed to 10° off the original heading, the rudder is
reversed to 10° to port or starboard (second execute); and
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).
The first overshoot angle is the additional heading deviation experienced in the
zig-zag test following the second execute.
The second overshoot angle is the additional heading deviation experienced in the
zig-zag test following the third execute.
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.
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.
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.