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DNV: Update Of The Manouevring Information After Installation Of Overridable Power Limitation

Monday, 17 June 2024 | 13:00

In March 2024, the IMO adopted the MEPC.390(81), an amendment to the MEPC.335(76), which provides guidelines on the shaft/power limitation system in order to comply with the EEXI. These guidelines now also include updating the manoeuvring characteristics for situations when shaft or engine power has been limited. Discover the details in this statutory news.

Relevant for ship owners and managers of ships above 400 GT with power limitation for EEXI compliance and flag states.

Wheelhouse poster, pilot card and manoeuvring booklet
Even though the impact of the overridable power limitation on the manoeuvring capabilities of the vessel is only marginal (see Appendix), the power limitation must be clearly indicated in the display of the manoeuvring information according to IMO Res. A.601(15).

To comply with the new requirements on installation of power limitations, DNV proposes to revise the propulsion particulars on the existing wheelhouse poster as follows (only the parts of the table highlighted in yellow need to be updated):

If the original values are struck through but can still be read, these values remain valid in case the power reserve is used. With the presentation method, no additional wheelhouse poster is required. If there is no adequate way to combine the values for the limited and unlimited condition in one poster, then a separate presentation using two posters is possible. The same information shall be updated in the pilot card and in the manoeuvring booklet. Submission of the three documents to DNV is only needed for ships with additional class notation NAUT(AW). For these ships, the manoeuvring booklet will be checked for approval.

Furthermore, if the documents are not updated, the ship might be considered as not in compliance with 33 CFR § 164.11 (k) by the U.S. Coast Guard.

The update of the manoeuvring information shall be carried out independently from the chosen limitation measure, whether EPL or ShaPoLi, active or alarm-based stand-alone solution. The requirement to update the information is also independent of the time needed to release the power limitation as stated in the OMM.

Nautical manoeuvres and the corresponding track plots
If new trials of the nautical manoeuvres were performed after installation of the power limitation, the plots of the nautical tracks should be revised accordingly in the wheelhouse poster. However, there is no requirement to perform such tests after installation of the overridable power limitation. Estimation of manoeuvring characteristics is acceptable, but some should be obtained from trials as stated in IMO Res. A.601(15).

The nautical manoeuvring tests comprise turning circles with hard rudder, inertia and crash stop, the Williamson turn, and zig zag tests as described in MSC/Circ.1053. Limit values are defined in IMO Res. MSC.137(76).

Class approval is only given for ships with additional class notation NAUT(AW). In this case, the test procedure must be submitted for approval before performance of new manoeuvres.

Recommendations

The behaviour of the crew is crucial for the safe handling of the ship. They should promptly:

Provide clear information to the pilots about the power limitation and point to new manoeuvring information.
Be familiar with the procedure to release the power limitation for using the power reserve.
Additionally, the load diagram, as provided in the main engine EPL report or the project guide from the main engine manufacturer, should be compared with the lever setting table. This allows the RPM to be determined below which the engine behaviour remains unchanged for stable conditions (operation in calm seas), as well as the corresponding RPM value for transient operation (e.g. acceleration and deceleration). A detailed explanation can be found in the Appendix (see pdf version of this news).

References
IMO resolutions/circulars: MEPC.335(76), MEPC.390(81), IMO Res. A.601(15), IMO Res. MSC.137(76), MSC/Circ.1053
DNV class rules: DNV-RU-SHIP Pt.6 Ch.3
USCG letters, for all vessels operating in waters within the USA: USA CFR 33§164.35-7, 16670 CG-ENG Policy Letter 01-24
Source: DNV

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