Automatic Mooring Systems

July 15th, 2006 by JCB
Posted in Articles, Features, Technical and Training | No Comments »

Automatic Mooring Systems

One of the highest risks to crews occurs during mooring and unmooring operations and another of the unacknowledged roles of the pilot is to ensure that the vessel is kept under control in frequently difficult and sometimes marginal conditions until the mooring operation is completed. Standing on an exposed bridge wing in a gale being lashed by a blizzard every pilot looks at the average mooring equipment and methodology of the mooring procedure and realises that the only aspect of the operation that has changed since the invention of the mechanical mooring winch in the 19^th century is that there are now less crew to operate them and the whole process of stoppering off ropes and wires (yes it still happens even on brand new ships!) and turning them up on bitts takes longer than it ever did!! Even on vessels equipped with mooring winches once the ship is in position the agony is prolonged as the moorings are then slacked down and a crew man grabs an improvised metal hook and hauls the mooring through a slot on the main winch onto a secondary drum where the turns must fill the drum and not overlap. Trying to hold a vessel under control whilst the elements do their damndest to defeat you brings two thoughts to mind. Firstly, we are not paid enough for the responsibilities that we shoulder and the second is, surely there must be a better way of mooring a ship in the 21^st century!! Well there is good and bad news here. The good news is that I am aware that two companies are now manufacturing and installing automatic mooring systems. However, before you all get too excited, these systems are expensive and require the shore to redesign their jetty configuration and most of all take full responsibility for the safety of the vessel whilst alongside. One system also requires specialist deck fittings. So the concept is fine for regular trades such as ferries and passenger vessels but for the other berths I think that we will just be watching with envy as the freight ferry slides into position, is grabbed or sucked alongside, and rings finished with engines all in the space of a few minutes!!

View the original pdf illustrated article from the magazine:

pilotmag.co.uk/userfiles/Pilotmag%20286%20(Jul%2006).pdf

However, it is interesting to examine the three systems currently in use provided by two manufacturers.

Vacuum Mooring

So far as I can ascertain the first company to establish a vacuum automatic mooring system was Mooring Systems Limited (MSL) who designed and manufactured the “Iron Sailor” vacuum system. MSL equipment has been adopted by several shipping and port companies especially in Australia and New Zealand.

Internal flush mounted.

The first “Iron Sailor” system, was installed on the rail passenger ferry Aratere (150m, 12,000 grt.) and since being commissioned in 1990 it has safely handled over 10,000 automatic mooring operations. This system is a specific ship based system that comprises of 4 units rated at 20 tonnes each. The units are positioned in pairs with two units forward on the ship and two units aft. When not in use they retract to be flush with the hull and when the vessel approaches the berth they are activated from the bridge wing extending out through hull doors to attach to a steel plate on the berth.

Externally mounted The externally mounted unit is designed to be retrofitted to

existing ships. The unit is stowed at deck level (when not in use). Activated by the master the units travel down the hull of the ship and couple with a plate mounted on the shore.

Recessed

The recessed system is designed to meet the needs of smaller craft such as barges and it permits them to automatically secure to larger vessels for transshipment operations.

It will be noted that all these vacuum systems can only attach to a flat metal surface. This obviously limits the vessel to specific berths where the shore pads can be precisely aligned with the vessel’s optimum mooring position. In the latter recessed system the barge can only use the system for mooring on the parallel flat side of a vessel which probably restricts its use on bunker barges and stores vessels which usually end up under the counter somewhere. I have never come across any vessels fitted with automatic mooring systems but apart from the flush mounted ferry arrangement I would suspect that being exposed to the elements both the externally mounted and recessed systems would very shortly succumb to contact damage and sea water corrosion. I would also anticipate that the installation and maintenance costs are very high which would impact on the cost benefit analysis.

Shore based system

This seems to be where the future lies because the vacuum pads are located on the jetty and lock onto the ship’s side. The only on board equipment required is the telemetry control system on the bridge wings which enable the master or pilot to

activate / de-activate the pads for remote mooring / unmooring operation. In March 2004, Mooring Systems Limited entered into an alliance with the Cavotec Group granting them the licence for the manufacture, marketing and service of their products. The mooring systems are now named “Moor Master” and can be tailored to suit various berth / vessel configurations with the advantage of compact storage when not in use. This also enables the system to rest behind the maximum fender impact line during berthing. When activated, the vacuum pad support frame is extended outwards and the vacuum mooring connection is established in around 10 seconds. Unmooring takes around 2 seconds.

How does it work?

Good question so here is the blurb from the brochure:

Instead of a rope, the products use vacuum pads to provide the mooring attachment. Each pad has a measurable working load, providing a powerful physical attachment between ship and shore. MSL’s vacuum pads have been tested and rated under the supervision of the international classification societies Det Norske Veritas (DNV) and Lloyds Register. When combined with the innovative, three dimensional supporting apparatus, the mooring units emulate the range of movement, resilience and elasticity of a line mooring. Today, MSL’s standard vacuum pads can cope with extensive surface irregularities and are able to slide under extreme loads without significant seal deformation or loss of attachment. Because the mooring units attach to the ship closer to the waterline and immediately counteract mooring forces, the system has a greater mooring efficiency than angled ropes. By using sophisticated internet based control software the system permits the user to monitor performance clearly communicating all essential mooring load information in real-time. Full control mechanisms and proper load measurement combined with robust communication systems are required to avoid unacceptable risks with the vacuum couple and the overall integrity of the mooring. Mooring load information is produced from the measurement of vacuum efficiencies and from monitoring athwartships and fore and aft hydraulic cylinders.

With a full knowledge of the mooring conditions at all times, the operator has complete control and understanding of the moored state of the vessel. MSL is currently the only company in the world to have successfully designed, implemented and proven ship vacuum mooring in a commercial environment. In this process they have discovered key elements of intellectual property relating to their designs and processes. MSL has protected these features having a number of patents pending internationally.

So, it would appear that the system is very robust with presumably a back up vacuum pump system and power supply in case of malfunction or power failure. The whole operation is totally automatic and once the vessel is alongside the vessel is moored by pressing a green button marked “moor”. Unmooring is achieved by pressing a red button marked “detach”.

What happens whilst the vessel is alongside?

The position of the vessel is monitored constantly and if there is a rise or fall in the tide the vacuum pads are mounted on vertical rails and move up and down with the vessel. If the tide range takes the pad to the extremity of the rail travel then in less than 15 seconds the pad will automatically detach from the hull, reposition

to the mid travel position and lock on again. In order that the vessel doesn’t break adrift the units are programmed not to relocate at the same time. This operation can also be undertaken manually at any time from the on board control panel. When mooring, the position doesn’t have to be exact. If once the pads are locked on it is found necessary to move the vessel this can be done by the pads themselves which can also move horizontally. The master or pilot just programmes in the distance to move ahead or astern and the pads will move the vessel the required distance. Again, if this distance is greater than the rail travel length then the pads will detach in sequence and re-locate automatically. With respect to wind effects the fact that these systems have mainly been fitted to ferries would indicate that they are capable of holding a vessel securely in high winds as claimed.

Why are they not everywhere?

Obviously such units don’t come cheap and as we are all aware berth operators are very reluctant to spend any money at all on even basic essentials such as fendering and in many cases they allow the berth to deteriorate to such an extent that when some unfortunate pilot comes alongside something falls off. The subsequent insurance claim then refurbishes the facility for a few more years! Exaggeration? Possibly but in London it has taken 4 years for a major container berth to fit sufficient bollard to moor a ship traditionally with the headlines/stern lines from two large container vessels sometimes all being placed on the same bollard and a new tanker berth was constructed with no bollards for breast ropes and these are still not present! The other factor here is liability and it is a major issue. Again on the Thames there is a facility which used to provide a shore gangway for a nominal charge. The gangway now sits unused because the berth operator has been advised that if they provide it they are liable for it whilst a vessel is alongside and if anyone is injured or killed whilst using it (the highest cause of maritime injury and death) they could be held liable. With a mooring system the berth operator is responsible for ensuring that it won’t fail whilst a vessel is alongside. The majority of berth operators will therefore baulk at the cost and liability aspects of automatic mooring systems so don’t chuck the long-johns or balaclavas away just yet!!

Other systems

I have discovered another company manufacturing and installing automatic mooring systems and this is a Swedish company called TTS Port Equipment who manufacture the “Automooring” system. This company has been commissioned by the Swedish Port of Trelleborg to provide mooring equipment for a railway berth. The specification demands that the system can handle a transverse load of up to 1,000 kN, for the Scandlines vessels Skåne and Mecklenburg, whilst berthed via a stern ramp. The Automooring system comprises of a framework fixed to the quay, inside which runs a vertically rolling unit activated by hydraulic motor. A mooring hook is connected to the unit and automatically centred within the fixed stand. Rather than a vacuum this system uses a hook and lug arrangement with dedicated equipment along with specialist control and telemetry units ashore and on board to connect the hydraulic shore mooring arms. Again the brochure makes the following claims:

Two hydraulic cylinders supply mooring force and the mooring systems are remotely controlled and therefore don’t require any quay-side personnel. The safety and efficiency of mooring procedures are improved by the system as its performance is monitored and its status is reported to operations staff in realtime. The system will require only one operator and will be remotely controlled with its load monitoring and alarm functions relaying information to operations staff in real-time. The design permits vessels to remain securely moored, even during power cuts or loss of control signals.

As with the Cavotec on board systems this arrangement requires a special slot and groove to be cut into the ships side which as well as being expensive will be vulnerable to contact damage and the elements.

Semi automatic Mooring

With this arrangement the vessel still uses its own mooring ropes but the shore

bollard is located on a hydraulically operated arm which tilts towards the ship

permitting the crew to drop the mooring rope over it. Once the rope is attached the

arm returns to the vertical and the line is tensioned in the usual manner. The bollard can be operated from the shore or from on board but again this system is only

practical for use with the same class of vessel for the bollard to correctly align

with the mooring point on the vessel. TTS also manufacture a vacuum system which looks very similar to the Cavotec equipment but the illustrations don’t seem to show any horizontal movement capability.

Conclusion

Well here we are in 2006 and I am sure that in 1906 few sailors when securing their ship would have thought that 100 years on their contemporary counterparts would be using similar mooring equipment and still turning ropes up on bitts. At least some companies are developing alternatives but the day when every ship can drop alongside a berth and be all fast in 10 seconds still seems a long way off!

Many thanks to Andy Bell MNI for providing the information on the Cavotec mooring systems.

PS I would be very interested to hear from anyone who has

experience of this equipment. TTS hook and lug

TTS semi automatic mooring