Sea Technology

AUG 2017

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Page 69 of 76 August 2017 / st 69 lift pairs of 40-ft. containers and place them with centimeter accuracy on the far side of the largest vessel in under 2 minutes. A 100-tonne lift is no prob- lem at all, but a gentle nudge from the flared bow or overhanging stern of a vessel can collapse 2,000 tonnes of steel in seconds and close a berth for months. Contacts like this are calcu- lated using energy equations, which allow some interesting comparisons to be drawn. The impact force of a large container ship maneuvering at less than walking speed, for example, is about the same as that from an artillery shell. A reinforced-concrete quayside can absorb it, but not a crane. The slewing cranes on cargo ships present another risk. Wear in the main slewing bearings, if not monitored and maintained within limits, can cause catastrophic failure. At the bearings' front (the side facing the load), wear comes from compression. The rear of the bearing, at the back of the crane, is subject to uplift and so wears in the op- posite direction. If uplift wear becomes too great, the bearing can simply come apart and cause the crane to topple over. In addition to the costs of a crane collapsing across a vessel and quay- side, the proximity of stevedores and crew, as well as the crane driver, can make such failures high consequence. Hong Kong solved the problem of Kai Tak by moving its airport, in the same way the Port of London moved from the Docklands. In a strange quirk of fate, a decade after the last Cathay Pacific jumbo negotiated its way through Kowloon, a cruise ship berthed at the new terminal built over the old airport's runway, and a few years after the last commercial ship de- parted London's Royal Docks, the first passenger jet touched down at the new City Airport. While moving a port's location can mitigate risk, the reality is that you can- not normally wait for this to happen. Human error cannot be fully eliminat- ed but can be mitigated by appropriate risk assessment, planning and proce- dures, coupled with ongoing vigilance, when approaching and leaving termi- nals and when in port, reducing the risk of avoidable accidents. ST India Docks, for example, which was excellent in the days of sailing schoo- ners, became increasingly tight when clipper ships gave way to tramp steam- ers and was impossibly difficult in the age of large-container carriers. Large ships find the confined channels and historical structures of older ports an obvious problem, but the wide chan- nels of a modern port can still create high overall risk exposure. New or old, all ports present unique challenges. A local pilot can aid in guiding a vessel to its berth. Pilots should be well versed in the idiosyncrasies of their harbors and approaches but are likely to be less aware of a specific vessel's behavior. Panama Canal apart, the ship's mas- ter remains responsible for navigating and avoiding collision, so the bridge team should ideally be familiar with each port they visit, as well as fully conversant with their vessel's slow- speed maneuvering characteristics. The crew need to remain vigilant, as- sessing and, if necessary, correcting pi- lot misjudgements or poor advice. Prior planning is key, as is a risk as- sessment that identifies fixed hazards and constraints, as well as variable issues from prevailing and forecast weather, tides, visibility and other shipping. Much like Hong Kong's old Kai Tak airport, some ports are reaching the end of their adaptation, so safe berth- ing can be as difficult as negotiating a 747 around Kowloon's skyscrapers. Controlling expense is always im- portant, but the cost of tug assistance or waiting at anchor should be bal- anced against the risk and conse- quence of allusion or collision. Human nature will instinctively accept a one in a thousand chance as being reason- able, and the application of conscious thought through assessment or recom- mended practices can more accurately balance the risk of a glancing impact to the quayside against any perceived expense savings. Ship-to-shore container cranes are one of the more frequent items dam- aged during berthing. Designed to perform a single job as rapidly and efficiently as possible, the biggest can Lorne Gifford is a chartered marine engineer and a reg- istered subsea engi- neer with 28 years' experience primarily in oil and gas with operating compa- nies, contractors and consultants. He has also worked in the development and engi- neering of offshore renewables and power interconnector projects, and provided tech- nical input for insurance claims relating to terminals and offshore infrastructure. D amage to marine infrastructure can range from a quayside contact that spalls a little concrete to headline events such as severing of a country's data and power cables. Big or small, these incidents tend to be expensive as claims often include business inter- ruption in addition to the cost of repair and reinstatement. The underlying cause of incidents is generally human error, be it poor judgement, failure of bridge manage- ment, inadequate route planning, or risk assessments that incorrectly ad- dress low-probability, high-conse- quence potentials. Human error can also be a factor in relation to the fixed object, such as failure to meet design standards, insufficient fendering or in- adequate integrity management. Less commonly, the root cause can be at- tributed to equipment or material fail- ure or, relatively infrequently, to force majeure. An example of fixed-object dam- age we see regularly at Brookes Bell is issues arising from berthing or un- berthing. Close proximity to multiple threats, a lack of room for maneuver- ing and poor slow-speed control com- bine with weather, tides, currents, in- ertia and momentum to make berthing and unberthing the most hazardous phase of any voyage. If the wind speed is high, visibility poor or tug assistance issues arise, then the perils magnify. Port layout can compound difficul- ties through inappropriate design and poor configuration. Ports grow and evolve over time, but commonly will only physically move when all avenues of adaptation have been exhausted. Ease of entry and berthing at London's soapbox Many Fixed-Object Damage Cases Could Be Avoided—Lorne Gifford

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