Section 4 Verification trials

4.1.1 For the assignment of the LMA or LNMA notation, representative manoeuvres are to be carried out during sea trials, in accordance with the guidelines in Vol 3, Pt 1, Ch 4, 5 Guidelines on conducting ship verification trials, to verify that the manoeuvring performance criteria defined in Vol 3, Pt 1, Ch 4, 2 Assessment for LMA notation or Vol 3, Pt 1, Ch 4, 3 Assessment for LNMA notation as applicable are achieved in practice.

4.1.2 Verification trials are normally to be performed with a clean hull and propeller in the presence, and to the satisfaction, of the LR Surveyor.

4.1.3 A report is to be submitted to LR detailing the test schedule and presenting the results of each manoeuvring trial in accordance with the guidelines in Vol 3, Pt 1, Ch 4, 5 Guidelines on conducting ship verification trials.

4.2.1 The verification trials are to take place in deep, unconfined waters, to minimise the interactive effects of the sea bed topography. The environmental conditions are to be as follows:

LMA notation:

• The water depth is not to be less than four times the deep draught of the ship.
• The wind speed should not exceed Beaufort 5.
• The wave sea state should not exceed 4.

LNMA notation:

• The water depth is not to be less than 5 times the deep draught of the ship or 0,0747V², whichever is greater.
• The wind speed should not exceed 15 knots.
• The wave sea state should not exceed 3.
• In both cases heavy swell is to be avoided.

4.2.2 The environmental conditions (wind, significant wave height, current and swell) are to be accurately recorded throughout the duration of the trials. The results of the trials are to be corrected to indicate the ship’s manoeuvring capability under zero wind, waves and current.

4.2.3 Where alternative environmental conditions have been specified for the purposes of demonstrating compliance with enhanced manoeuvring criteria, these are to be agreed between the designer and the Owner and specified in the agreed trials code.

4.3.1 The trials are normally to be carried out with the ship in a normal operational condition within a five per cent deviation of the deep draught and trim.

4.3.2 Where it is impractical to conduct trials at the deep draught, they may be conducted at a draught as close to the deep draught as possible with minimum trim and sufficient propeller immersion.

4.3.3 Where trials are conducted in a condition other than that required by Vol 3, Pt 1, Ch 4, 4.3 Draught conditions 4.3.1, the necessary manoeuvring characteristics are to be estimated for the trial and full load condition using an acceptable method, and the results are to be submitted to LR for assessment.

4.4.1 The approach speed for the assessment under Vol 3, Pt 1, Ch 4, 2 Assessment for LMA notation (LMA notation) is to be at least 90 per cent of the ship’s speed corresponding to 85 per cent of the maximum engine output.

4.4.2 The approach speed for the assessment under Vol 3, Pt 1, Ch 4, 3 Assessment for LNMA notation (LNMA notation) is to be the required verification speed for that mission type.

4.4.3 Before the execution of the relevant manoeuvre, the ship must have run at constant engine(s) setting with minimum rate of change of heading (steady course).

4.5.1 Representative manoeuvres are to be carried out to an agreed trials code, and are to include the following:

1. The performing of one turning circle to port and one to starboard with 35 degrees rudder angle (or the maximum rudder angle) for the following approach conditions:

   • Conditions defined in Vol 3, Pt 1, Ch 4, 4.4 Approach conditions, coupled with a pull-out manoeuvre.
   • Full sea speed.
   • Half manoeuvring speed.

2. Ship’s stopping manoeuvre from full ahead manoeuvring speed achieved by stopping the engine.

3. Ship’s stopping manoeuvre from full sea speed achieved by the application of full astern thrust.

4. Ship’s stopping manoeuvre from the approach conditions, defined in Vol 3, Pt 1, Ch 4, 4.4 Approach conditions, achieved by the application of full astern power.

5. A 10º/10º zig-zag manoeuvre, under the approach conditions defined in Vol 3, Pt 1, Ch 4, 4.4 Approach conditions.

6. A 20º/20º zig-zag manoeuvre, under the approach conditions defined in Vol 3, Pt 1, Ch 4, 4.4 Approach conditions.

7. Initial turning manoeuvre at the approach conditions defined in Vol 3, Pt 1, Ch 4, 4.4 Approach conditions.

8. Man overboard manoeuvre, such as the Williamson turn or an elliptical turn, to both port and starboard at full sea speed.

9. Transverse thruster manoeuvres, if applicable, with the ship stopped and all thrusters at maximum power to turn the ship 180 degrees to port and to starboard.

4.5.2 Provision is to be made in the trials agenda for the execution of a spiral manoeuvre where the results of the pullout manoeuvre indicate excessive dynamic instability or the values for either the first or second overshoot angles, measured during the 10º/10º zig-zag manoeuvre, exceed the following:

4.6.1 Specific manoeuvres are to be carried out to an agreed trials code. The scope of the manoeuvres is to be agreed between LR, the Owner and the Naval Administration in the sea trials procedures.

4.6.2 Compliance with Vol 3, Pt 1, Ch 4, 3.3 Manoeuvring performance criteria 3.3.3 will also require the manoeuvres defined in Vol 3, Pt 1, Ch 4, 4.5 Representative manoeuvres (LMA notation) to be conducted as a minimum.