Mooring lines may not grab the headlines – unless they break – but this essential technology requires regular supervision and an industry-wide approach to ensure safety and legality
As with other practical areas of tanker operation, the use of mooring ropes is not guided by a regulatory body, but by an industrial association.
Oil Companies International Marine Forum (OCIMF) is a voluntary association of oil companies with an interest in the shipment and terminalling of crude oil, oil products, petrochemicals and gas. There are currently 109 company members, led by an executive committee, currently chaired by Chevron president Mark Ross. Other committees cover areas of special interest, such as the technical operation of tankers.
The OCIMF remit includes developing and publishing guidance, recommendations and best practice by harnessing the skills and experience of the members and the wider industry. It is under that practical approach that, since 1992, OCIMF has published Mooring Equipment Guidelines 4 (MEG4), the industry standard publication for tanker mooring.
In July 2018, OCIMF published the fourth edition, which addresses questions raised by readers since the third edition was published in 2005. The technical content has been thoroughly reviewed and updated. The new edition contains guidance to enhance the safety of mooring, including a human-centred design approach to mooring arrangements and increased focus on the use and understanding of mooring lines and tails.
OCIMF director Rob Drysdale said: “Updating the Mooring Equipment Guidelines has been a major undertaking that has resulted in comprehensive changes from the last edition. I believe this new edition will create a step change in mooring safety that will have a direct impact on reducing incidents and injuries.”
Naturally, mooring rope manufacturers will have to update support material to incorporate the changes in MEG4. To this end, Samson, a developer of high-performance synthetic rope solutions has announced the launch of a new integrated technology and service solution, Icaria, designed to facilitate the transition process to MEG4 operational best practices.
OCIMF’s release of the fourth edition of its Mooring Equipment Guidelines requires a significant change in how mooring systems will be designed, selected, maintained and retired.
OCIMF’s release of the fourth edition of its Mooring Equipment Guidelines requires a significant change in how mooring systems will be designed, selected, maintained and retired. In addition, terminology has been clarified, a robust framework has been created to improve mooring line selection and purchase, and design guidance updated to improve mooring line longevity.
“As the regulatory environment evolves, vessel owners and operators have the opportunity to upgrade tools and systems to ultimately improve safety” said Samson director of engineering, Kris Volpenhein.
“Icaria is designed to streamline implementation of MEG4 best practices by providing advanced tools, services, consultation and support for both new and existing vessels. Icaria customers will have support in both MEG4 plan development and implementation.”
Icaria is designed to streamline implementation of MEG4 best practices
According to Samson, Icaria helps facilitate the transition process by helping with the selection or confirmation of the appropriate mooring line system, identifying gaps and focus areas for more frequent or robust maintenance routines, and making recommendations for service life expectations.
“Samson has a long track record supporting the shipping industry since converting the first fleets from steel wire,” said Mr Volpenhein. “Icaria is a major evolution in that service, which will allow us to provide proactive and collaborative line maintenance, allowing owners and operators to safely optimise line life while reducing operational risk.”
Beyond compliance support, Icaria also includes learning management, training, and certifications for crew members to improve the decision-making process.
Calculating mooring rope tension
Mooring rope manufacturers can advise on the specification and amount of mooring rope needed. Tension Technology International is a supplier of mooring software, Optimoor, that facilities this calculation.
Optimoor can calculate the non-linear rated breaking strength (RBS) and load-extension characteristics for mooring lines. Data is provided for wire, aramid, HMPE, nylon double braid, nylon plaited and stranded, polyester, and polypropylene. For synthetic ropes, both slow and dynamic response is modelled automatically.
Optimoor calculates exposure areas, wind and current coefficients, and the resulting environmental forces on the vessel. The display shows the vessel’s movements and mooring forces. In addition, mooring line loads are shown in tonnes (or kips) and percentage of RBS.
The software contains a single command function to reset target pretensions. Another function brings all lines up to the optimum tension for minimum vessel movement. The user may alter individual line tensions (in a manner analogous to tending the mooring winch) to bring the mooring line load distribution into better balance. A single command sweeps the wind through 360 degrees to determine the “worst-case” loading on each line and a graphic wind or wave rosette can be generated.
Optimoor has provision for initial and final draft and trim conditions and times. It also supports tidal variations via tidal tables and can apply automatic application of local correction factors. With these inputs, line tending requirements can be anticipated by stepping forward in time by minute or hourly intervals. A single key command “fast forwards” and displays the times at which the various lines would become overloaded.
The simulation software can also be used for vessel and port personnel to train in techniques for arranging and tending mooring lines. The advantages and problems of various mooring arrangements can be explored and demonstrated.
Upgraded chocks and legal matters
Even the best maintained, well lubricated wire rope will be rough and abrasive by the time it requires replacement. As a consequence, the micro and macro rust particles act like sandpaper and create grooves on chocks that will damage new synthetic rope.
Nylacast has introduced Chock Liner, which has a patented low-friction technology, supporting the safe and reliable mooring of vessels of all type and purpose.
A major weakness of fibre rope is its poor resistance to external abuse and abrasion through everyday operations and poor surface contact. Abrasion continues to be one of the most common root causes of rope failure and reduction in its residual strength.
Changing to synthetic ropes requires elimination of abrasive surfaces
It is impossible for synthetic rope to perform to its maximum capabilities when used with poorly maintained deck equipment. Rope manufacturers recommend surfaces are correctly prepared, maintained and routinely inspected before and after rope installation. A 300-micro-inch finish (7.62 microns) is recommended for all deck hardware that comes into contact with rope, in addition to avoiding chocks heavily scored from previous wire rope use.
The Chock Liner mooring technology provides vessels with the ability to be moored with greater safety. There is no need for crew members to be near mooring lines under tension and minimal chafe protection is required following installation.
Innovations like Chock Liner are useful in preventing damage to expensive synthetic ropes, but even careful adherence to best practice will not prevent legal problems arising if the allocation of risk is not carefully specified in charterparties.
A typical time charterparty will state that the owner has agreed that on delivery, the vessel will be “…in every way fitted for service” and to “provide and pay for …all necessary stores…to keep the vessels in a thoroughly efficient state in hull, machinery and equipment… for and during the service”.
What happens if the port or terminal insists the vessel berths with more mooring lines than the vessel has on board?
However, what happens if the port or terminal insists the vessel berths with more mooring lines than the vessel has on board? North of England P&I Club has issued the following advice in relation to London Arbitration 19/01.
A charterer ordered a vessel on time charter to a port where it was the port’s requirement that vessels should use 14 mooring lines of 220 m length. The vessel had five mooring lines of 197 m length. Extra mooring lines were hired.
London Arbitration held that:
However, North of England P&I Association noted that had the vessel been fixed under a time charterparty, where the charterer must give notice of intended service, and that had not included the port or region, then it would have been reasonable for London Arbitration to find for the owner.
So how can owners minimise the scope for disputes? One possibility is for the shipowner in the charterparty “Descriptions Clause” to declare the number and length of the mooring ropes available. While the charterer may argue that number may have been insufficient, the tribunal may be more sympathetic given the shipowner had made the specifications clear in the negotiations and in the charterparty.
The shipowner’s case would be strengthened if the charterer did not protest the number and length of mooring ropes when the vessel was delivered were insufficient for “ordinary cargo service” or “intended service.”