Sea Trial – Maneuvering Tests
The maneuvering tests to be carried out under the scantling Draft of 13.00m (A small stern trim may be acceptable). The test to be carried out at smooth tidal current and with wind force of not more than Beaufort 4. Record the wind direction and speed.
Full Astern Stopping Test (only for the first vessel of series)
The vessel runs ahead at M/E abt. 85%MCR (abt.124 rpm), when the ship speed and course are stable, give an order to full astern. When revolution of M/E falls to the specified point that M/E can change direction safely, full astern is made. Stopping distance, stopping time and changing of course angle are to be measured by DGPS from the time of stop order given to the vessel stopping (with the zero speed shown on the log).
Standards
The track reach in the full astern stopping test should not exceed 15 ship lengths. However, this value may be modified by the Administration where ships of large displacement make this criterion impracticable, but should in no case exceed 20 ship lengths.
Stopping Test (only for the first vessel of series)
Stopping test to be carried out for full speed. The vessel runs ahead at M/E abt. 85%MCR (abt.124 rpm), when the ship speed and course are stable, give an order to stop. Stopping distance, stopping time and changing of course angle to be measured by DGPS from M/E stopping to the vessel speed which falls to 5 knots (shown on the log).
Turning Circle Test (only for the first vessel of series)
Turning circle test to be carried out for full speed.
1.) The vessel runs ahead at M/E abt. 85%MCR (abt. 124 rpm), when the ship speed and course are stable, straight course to be held by a small rudder angle operating.
2.) Start the DGPS recorder when the vessel runs at a constant speed for about 3 minutes, and give an order to move the rudder hard over (35° P & S respectively). After the vessel has already finished sailing over a degree about 720°, one test is finished.
3.) The sailing track of vessel to be recorded by DGPS, and the track drawing to be supplied in Trial Report. The diameters of turning circle and the maximum inclinations of the ship during the test to be indicated.
4.) The test to be carried for both sides.
5.) Standards: The advance should not exceed 4 ship lengths (L) and the tactical diameter should not exceed 5 ship lengths in the turning circle manoeuvre.
Zig-Zag Test (only for the first vessel of series)
10° /10° Zig-zag test to be performed by turning the rudder alternatively by 10° to either side following a heading deviation of 10° from the original heading. The vessel runs ahead at M/E abt. 85%MCR (abt.124 rpm), when the ship speed and course are stable, move rudder quickly as the following steps:
(1) 0° -10° left (Holding until ship’s heading is 10° to the left of original course).
(2) 10° left- 10′ right (Holding until ship’s heading is 10° to the right of original course).
(3) 10° right-10° left (Holding until ship’s heading is 10° to the left of original course).
(4) 10° left – 10° right (Hold until ship’s heading is 10° to the right of original course, then end).
In every step, record the times of rudder operating, and record the ship speed and course changing.
Standards
The value of the first overshoot angle in the 10°/10° zig-zag test should not exceed:
- 10° if L/V is less than 10 s;
- 20° if L/V is 30 s or more; and
- (5 + 1/2(L/V)) degrees if L/V is 10 s or more, but less than 30 s,
where L and V are expressed in ‘m’ and ‘m/s’ respectively.
The value of the second overshoot angle in the 10°/10° zig-zag test should not exceed:
- 25°, if L/V is less than 10 s;
- 40°, if L/V is 30 s or more; and
- (17.5 + 0.75(L/V))°, if L/V is 10 s or more, but less than 30 s.
Reference: Sea Trial Procedure