Automated mooring: a safer solution for dynamic environments

26 Sep 2011 - AtoN and Mooring/Berthing

Mooring vessels using ropes is a time-tested tradition going back thousands of years. But, as the saying goes, if it ain’t broke, why fix it?

“Ropes have a tendency to snap. They need to be man-handled; there’s no good way of automating the attachment of ropes for ships,” says Patrick Rosenwald, MD of Cavotec’s MoorMaster automated mooring Centre of Excellence. “They are man-handled and, as a consequence, there are people next to ropes that can snap, and those ropes, when they snap, have a lot of energy in them. They actually kill people quite often.”

Indeed, in September last year a deckhand aboard the MV Flumar Brasil was killed when a mooring line jumped off the mooring bitt. The seafarer was hit on the forehead by the loose line, knocking off his helmet and throwing him against a closed chock, the Maritime Accident Casebook reports.

Two seafarers sustained severe leg injuries after three lines snapped during the mooring of the Ruiloba container vessel in Bremerhaven, 2009.

Bob Couttie, of the Maritime Accident Casebook, says he even knows of one mooring accident where three men were sliced in half at the waist by a snapped mooring line.

The case for automated mooring as a safer solution than traditional techniques is a strong one.  Instead of ropes, the basic feature of each MoorMaster unit is a 20-tonne vacuum pad, which generates suction to attach to the side of vessels and hold them at berth.

Where ropes store up potential energy from the vessel’s movements, causing them to snap, the MoorMaster does not store up any of this energy. Each pad’s hydraulic triple axis arms enable the unit to move in three planes simultaneously, compensating vessel motion and automatically adjusting the vessel’s position.

“What we’re finding, more and more, is that there is much more interest for MoorMaster in ports with what we call “dynamic environments” – ports that are wave-affected, and where ropes aren’t really a feasible option, and they’re not really capable of coping with the dynamic situation,” says Rosenwald.

Fast mooring: big money benefits

Safety of those working on the berth is always of paramount importance, but another benefit of automated mooring lies in the speed at which vessels can be moored.

“A typical container ship, for example, takes about half an hour to moor with ropes,” Rosenwald says. “You have, usually, four to six people onboard the ship dedicated to the mooring, and a similar number on the berth. So in total using, let’s say, up to 12 people for about half an hour, doing a relatively unproductive job.

“With the MoorMaster, basically we can attach to a ship and secure it in about 30 seconds – a rather large difference. In many applications this is already a massive advantage.”

Ferry operators are already taking advantage of these fast turnaround times. In Denmark, Nordic Ferry Services has installed four MM400 units as part of its high-frequency passenger ferry routes between the island of Samsø and the mainland. “In Denmark, the whole business model they had was based on fast mooring, allowing them to do more return trips per day, and this gave them a competitive advantage over the competition,” says Rosenwald.

At Cavotec’s MoorMaster installation at Port Hedland, an iron ore loading facility in Western Australia, automated mooring saves the Port roughly an hour per ship, allowing the facility to streamline its operations and make savings that run into hundreds of thousands of dollars.

Being able to moor vessels faster also means the ship’s engine and those of the tug boats around it need to run for between 1.5–2 hours less than in traditional mooring operations, saving money on fuel and reducing the volume of the carbon emissions from exhaust fumes.

Infrastructure savings

With traditional mooring techniques, the berth needs to be much longer than the vessel being moored, in order to get ropes down both in front of and behind the vessel. Because the MoorMaster units only attach to the middle 60–70% of the ship, a much bigger vessel can be moored to the same sized berth – reducing the need for extending the berth, and hence saving money.

“This is the case for at least two of our applications,” says Rosenwald, “the one in Denmark with the ferry, and also in Port Hedland, Western Australia, where they are able to moor ships that are much larger than what would be possible with rope mooring.”

The million dollar question

The vacuum pads of each MoorMaster unit function using an accumulator of vacuum – “basically a big storage area of nothing,” as Rosenwald calls it – which is powered by electricity. The units are controlled by means of a programmable logic controller (PLC), motion controllers and a computer system hooked up to the Internet, which allows MoorMaster units to be monitored from anywhere in the world. 

The units use a fairly modest supply of energy, especially in comparison with other port equipment. In a highly dynamic environment, a MM200 unit may use around 26kWhr of electricity to moor a vessel. In a typical ferry application, an MM400 unit consumes around 15kWhr of energy.

But the big question is: what happens when the power goes down?

"All of our controls and communications hardware are under UPS, so even if the power goes down they will remain live, so we can continue communicating with the system, and more importantly the system can communicate to the operator," Rosenwald says. This also ensures that when power is restored the system recovers elegantly.

"Generally, we can guarantee a minimum of 15 minutes attachment time, but this can be much more depending on the quality of the side of the ship." In any case, the company recommends that operators install auxiliary generators where power supply is unreliable – just in case. While the vacuum remains safe for quite some time the hydraulic systems still need power.

Tailoring different mooring units to different applications

 Of course, each port application is different and Cavotec has developed a range of configurations of the basic vacuum pad design for different installations.

The MM200, Cavotec’s biggest seller, is a compact design based upon an elbow mechanism, and is rail-mounted on the front of the berth – ideal for applications where space is limited. “For example,” Rosenwald says, “in a typical container terminal you don’t have a lot of space in between the crane rail and the edge of the berth, so you can’t start installing big machines on the top of the berth to do the mooring.”

The MM400, on the other hand, is fitted with two of these 20-tonne vacuum pads, and is fitted to the top of the berth. “It’s quite useful and quite easy to install because basically you stick a few bolts in the top of the berth and attach the unit and that’s it,” says Rosenwald. “The problem is that it takes up quite a bit more berth space, but for certain applications – for example, a typical ferry application – this is not an issue because, with a ferry, you just have a gangway for the passengers and a ramp for the cars at the back, so space on the berth isn’t really at a premium at all.”

The company has also developed the MM200LS (lock system) unit, which has been specifically designed for use in river locks. Several of these units are already in operation in the St. Laurence Seaway, Canada, and were developed specifically for the existing infrastructure there. Implementation of a MoorMaster doesn’t start or end with screwing the unit into the berth. As Rosenwald says, “Every project we’ve been involved in, we’ve had to dedicate quite a few design resources to ensure the adaptation to the infrastructure that the client has.”

Where automated mooring works well, it works well because the units have been adapted to allow a custom fit – not just in literal terms on the berth, but a perfect match with the desired improvements in operational performance, whether it be improving vessel turnaround times, making infrastructure savings, or simply making a long-term investment in the safety of port staff.