Some of the common failures are:
#1 Inadequate lines
Several times the choice of a mooring line was based on wrong criteria, resulting to reduced response of the line. Additionally, even if the criteria were as required, the inadequate storage or maintenance procedures may also led to same results. For example, a new set of two mooring lines delivered on board. Safety officer provided guidance for storage and logged their certificates in the appropriate file. When the next safety officer arrived on board (due to crew change) there was no evidence which certificate accompanies each line. Furthermore things may have been more complex if one or both of these ropes were used on different mooring stations.
#2 Inadequate Mooring equipment use
Having the correct lines on board does not necessarily means smooth operations. The installed equipment on board may also create problems. Mooring winches, capstans, fairleads, chock, bollards etc, are to be manufactured and installed under specific requirements based mostly on the supported lines size, length and minimum breaking load. C
Common errors are the inadequate setting for winch breaks, inadequate maintenance of equipment and the condition of mooring decks (sharp edges etc). Especially for the winch breaks, it is very common after maintenance on winches, crew to forget to re install the break on the correct load as per mooring lines % of Ship Design MBL used on the winch.
All equipment on board (lines and supportive installations) have been assessed during construction in respect of specific environmental conditions. Both IMO MSC.Circ 1175 and OCIMF MEG-4 have such conditions as reference, in order to set the maximum limits of mooring systems use.
However, one reason we still report failures is that even though most of ports and terminals have their own specific limits of environmental conditions, the commercial time schedule pressure is such that in some cases these limits are overlooked. Furthermore, in some other cases, Masters fail to predict or understand the forthcoming weather conditions or environmental parameters (waves, tides, currents etc).
The regulatory requirements for the size, length and minimum breaking load of mooring lines should be followed as well as IMO MSC/Circ.1175 and relevant IACS guidance. The OCIMF MEG-4 is also a recommended approach on calculating Ship Design MBL and other relevant parameters.
Having chosen the right lines, the next step is to know the exact position of each line on board. A detailed log with positions on board should be followed. The OCIMF MEG-4 requirements for a detailed Line management Plan and the Mooring Equipment register are recommended.
- identified position for each line on board
- manufacture date
- date of first use on board and
- hours under tension.
All mooring lines are subject to a specific expected service life, based mainly on manufacturer’s experience and data. This service life may be expressed in hours under tension (eg 2,000 hours) or in period (eg 5 years). No matter the method used, an effective monitoring and logging system should support it.
The log used in the mooring plan should include a detailed way of monitoring (hours under tension for example) in order to determine when a line should be inspected, when it will be subject to end for end change or when it will be retired.
Levels of a rope inspection
In addition, effective maintenance procedures should be be followed. For each rope, the following three levels of inspection take place:
- Deployment Inspection: it is conducted on working length of the line (outboard of the tension side of the winch), during every mooring operation, by ship personnel assigned to specific mooring station. The working length of the line (outboard of the tension side of the winch) should be inspected for defects which may impair the performance of the line.
- Routine Inspection: A full-length line inspection based on visual external and internal inspection. Jacked lines to be inspected in accordance with manufacturers’ requirements. This inspection is to be conducted periodically in accordance with Company’s maintenance schedule by trained, qualified and experienced personnel.
- Detailed Inspection: A full-length detailed inspection including all internal and external tests, conducted by third party or manufacturer representative, to be conducted when the line is near to reach the end of expected service life.
End for End Policy
All mooring ropes that are fitted on the winches should be rotated periodically as per Company’s policy, in order to ensure that ropes, which are exposed to heavy load conditions, are not exposed for extended periods. This practice will increase their service life.
- In order to ensure continuity, the ropes need to be rotated (irrespective of whether they have been replaced).
- If a mooring line during inspection shows signs of damage near the splice or on the splice, it must be reversed in order to use the other side of the rope/wire.
- Each line to be reversed end for end only once. The date of the end for end change and the total hours under tension should be marked.
Overall, good planning is key in order to avoid failures after mooring. In this regard, Master should review weather forecast, terminal experience and limits, local environmental conditions in order to decide the berthing approach, number of mooring lines to be used and mooring position monitoring during stay. A toolbox meeting to provide information to mooring parties is essential as well. Roles and responsibilities of each crew member should be clearly defined; therefore, an effective communication plan between parties and shore personnel is of outmost importance.