Section 5 Trials
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Ships, July 2022 - Part 5 Main and Auxiliary Machinery - Chapter 1 General Requirements for the Design and Construction of Machinery - Section 5 Trials

Section 5 Trials

Parent topic: Chapter 1 General Requirements for the Design and Construction of Machinery

5.1 Inspection

5.1.1 Tests of components and trials of machinery, as detailed in the Chapters giving the requirements for individual systems, are to be carried out to the satisfaction of the Surveyors.

5.2 Sea trials

5.2.1 For all types of installation, the sea trials are to be of sufficient duration, and carried out under normal manoeuvring conditions, to prove the machinery under power. The trials are also to demonstrate that any vibration which may occur within the operating speed range is acceptable.

5.2.2 The trials are to include demonstrations of the following:

  1. The adequacy of the starting arrangements to provide the required number of starts of the main engines.

  2. The ability of the machinery to reverse the direction of thrust of the propeller in sufficient time, under normal manoeuvring conditions, and so bring the ship to rest from maximum service speed. Results of the trials to be recorded.

  3. The ability to permit astern running at 70 per cent of the full power ahead revolutions corresponding to the maximum continuous ahead power for which the vessel is classed.

  4. In steam turbine installations, the ability to permit astern running at 70 per cent of the ahead revolutions corresponding to the maximum continuous ahead power for which the vessel is classed. This astern trial need only be of 15 minutes' duration, but may be extended to 30 minutes at the Surveyor's discretion. To avoid overheating of the turbine due to the effects of ‘windage’ and friction, the astern trial is not to exceed 30 minutes or the manufacturer’s recommendation.

5.2.3 Main propulsion systems are to undergo tests to demonstrate the astern response characteristics. The tests are to be carried out over at least the manoeuvring range of the propulsion system and from all control positions. A test plan is to be provided by the yard and accepted by the Surveyor. If specific operational characteristics have been defined by the manufacturer, then these are to be included in the test plan.

5.2.4 The reversing characteristics of the propulsion plant, including the blade pitch control system of controllable pitch propellers, are to be demonstrated and recorded during trials.

5.2.5 Where controllable pitch propellers are fitted, the free route astern trial is to be carried out with the propeller blades set in the full pitch astern position. Where emergency manual pitch setting facilities are provided, their operation is to be demonstrated to the satisfaction of the Surveyors.

5.2.6 In geared installations, prior to full power sea trials, the gear teeth are to be suitably coated to demonstrate the contact markings, and on conclusion of the sea trials all gears are to be opened up sufficiently to permit the Surveyors to make an inspection of the teeth. The marking is to indicate freedom from hard bearing, particularly towards the ends of the teeth, including both ends of each helix where applicable. The contact is to be not less than that required by Pt 5, Ch 5, 4.2 Accuracy of gear cutting and alignment or Pt 5, Ch 5, 5.2 Meshing tests, as applicable.

5.2.7 The following information is to be available on board for the use of the Master and designated personnel:

  • The results of trials to determine stopping times, ship headings and distance;
  • For ships having multiple propellers or multiple steering-propulsion arrangements, the results of trials to determine the ability to navigate and manoeuvre with one or more propellers or steering-propulsion units inoperative.
  • For ships having a single propulsor driven by multiple engines or electric motors, the results of trials to determine the ability to navigate and manoeuvre with the largest engine or electric motor inoperative.

5.2.8 Where the ship is provided with supplementary means for manoeuvring or stopping, the effectiveness of such means are to be demonstrated and recorded as referred to in Pt 5, Ch 1, 5.2 Sea trials 5.2.7.

5.2.9 The stopping distance achieved when ship is initially proceeding ahead with a speed of at least 90 per cent of the ship's speed corresponding to 85 per cent of the maximum rated propulsion power should not exceed 15 ship lengths after the astern order has been given. However, if the displacement of the ship makes this criterion impracticable then in no case should the stopping distance exceed 20 ship lengths.

5.2.10 For main propulsion systems with reversing gears, controllable pitch propellers or electric propeller drive, running astern is not to lead to the overload of propulsion machinery.

5.2.11 All trials are to be to the Surveyor's satisfaction.

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