Lloyd’s Register (LR) has given insight regarding the regulatory requirements for updating stability information when alterations are made to a ship.
SOLAS (Chapter II-1, Reg 5.4) requires that where any alterations are made to a ship so as to materially affect the stability information supplied to the master, amended stability information must be provided.
Shipowners and ship managers should be aware that lightship property changes are subject to regulations regarding testing, stability information and reapproval of calculations as required by the following:
- SOLAS Regulation II-1/5.4
- IMO Resolution MSC.429(98) Rev.2 – Revised Explanatory Notes to the SOLAS Chapter II-1 Subdivision and Damage Stability Regulations
All ships to which SOLAS Regulation II-1/5.4 applies must comply with the above, regardless of their construction date.
New inclining test
SOLAS requires a new inclining test to be carried out, and the stability information to be reapproved, whenever the below parameters have increased or decreased beyond acceptable limits:
- Lightship displacement (lightweight) exceeding 2%; or
- Longitudinal centre of gravity (LCG) exceeding 1% of L (length as defined in the International Convention on Load Lines); or
- Vertical centre of gravity (VCG) exceeding 1%.
Recalculation and reapproval
Additionally, when a ship does not exceed the deviation limits specified above, all stability information should be recalculated and reapproved using the new calculated lightship properties, if any of the following deviations from the approved values are exceeded:
- Lightship displacement (lightweight) exceeding 1%; or
- Longitudinal centre of gravity exceeding 0.5% of L, either forward of aft;, or
- Vertical centre of gravity exceeding 0.5%.
Record of alterations
Ships are required to maintain a record of alterations and the associated deviations to lightweight and centre of gravity. The records must be placed together with the approved Trim & Stability Booklet onboard the vessel.
The record should consider the effect of cumulative changes, meaning that smaller modifications individually considered may not be sufficient to produce a significant change, but when the cumulative effect is considered, the permissible deviations may be exceeded.
The deviations are to be obtained by a detailed calculation of “weights on” and “weights off” a ship resulting from all alterations to the ship since the date of the last approved inclining test, to determine the adjusted lightship properties. Lightship properties include weights and the centre of gravity.
Appraisal of calculations
When carrying out any alterations or modifications, shipowners must submit the lightweight properties calculations for appraisal to Lloyd’s Register (LR), including:
- A report containing detailed calculation of weights added to, removed from and relocated on the ship, that are a result of all alterations to the ship since the date of the latest approved inclining test. In addition, the report must contain the new lightship particulars, as well as calculation of the deviations compared with the reference lightship of the ship.
- Supporting evidence, such as manufacturer datasheets, drawings, etc. of the modification being carried out.
- Latest approved ship- specific stability information booklet along with its addenda (if any).
- Latest endorsed Inclining Test report (if not included in the approved stability information booklet).
- The latest endorsed Lightweight Survey report (if not included in the approved stability information booklet).
- Endorsed added weight calculations report(s) related to previous alterations (if any).
- Updated general arrangement plans showing the modification.
- Existing general arrangement plans before the modification.
- Should the threshold be exceeded, Stability Information must be updated unless agreed otherwise by the flag Administration.
