Sea trials are carried out after the dock tests to demonstrate proper operation of the main and auxiliary machinery, including monitoring, alarm and safety systems, under realistic conditions. The trials are also to demonstrate that any vibration which may occur within the operating speed range is acceptable.
The sea trials are to include demonstration of the following:
- The adequacy of the starting arrangements to provide the required number of starts of the main engine.
- The ability of the machinery to reverse the direction of thrust of the propeller in sufficient time, and so bring the ship to rest from maximum service speed.
- Where controllable pitch propeller is fitted, the free route astern trial is to be carried out with the propeller blades set in the full pitch astern position.
- 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 make for an inspection of the teeth.
Further reading: GL Guidelines for Sea Trials of Motor Vessels.
From BNC Technical Specification:
1. Speed trials and manoeuvring trials should be made with no wind and sea as still as possible.
2. Manoeuvring trials are to be performed according to the IMO Res. Res. MSC.137(76) “Standards for Ship Manoeuvrability”, and will be carried out for the first ship only.
3. The scope of the sea trials and inspections after sea trials will be specified in the Sea Trial Program that is to be prepared by the Shipyard and submitted for Owners approval 2 months before sea trials.
4. Sea trials will be carried out when all dock tests are completed with positive results. In a justified case agreed with Owners, a dock test can be carried out during sea trials.
5. The Shipyard is to give Owners and Class Society a three-week notice of the date of sea trials and to confirm it seven days before the date.
6. Spead trials are to be performed in sufficient deep water.
7. Noise and vibration measurements will be carried for all ships. However, in case of good results on the first ship, these measurements can be suspended by Owners for the sister ships.
8. In case of any breakdown that can be repaired at sea, sea trials shall be continued after repairs and remain valid in all respects.
9. Unsuccessful sea trials will be repeated when faults/claims are rectified, within a scope necessary to confirm that corrections are made properly.
10. After finishing sea trials, the Shipyard shall prepare the document entitled Sea Trial Results.