Features
SQUAT: PART 2: MUD NAVIGATION & NEGATIVE UNDER KEEL CLEARANCE
Whilst wading through the various documents to produce the article on squat in the January issue, I came across several references to the linked topic of muddy water navigation and the concept of negative under keel clearance (UKC). Read the rest of this entry »
SQUAT PART 1:ARE WE OUT OF OUR DEPTH?
A tanker in a restricted channel. According to squat tables this tanker should be aground! Photo :JCB
PILOT GIGS OF CORNWALL AND THE SCILLY ISLES
THE PILOT GIGS OF CORNWALL AND THE SCILLY ISLES
The pilot gigs of the Isles of Scilly and Cornwall are totally unique six oared open boats which were used to ship pilots onto ships arriving of the South West approaches to the United Kingdom. This feature actually started as a review of a fascinating book that I found in the bookshelf of a holiday let in Cornwall. Titled : “Azook: The Story of the Pilot Gigs of Cornwall and the Isles of Scilly 1666 – 1994”. Read the rest of this entry »
Crimson Mars Investigation
CRIMSON MARS GROUNDING
Read the full ATSB report www.atsb.gov.au/publications/investigation_reports/2006/MAIR/pdf/mair227_001.pdf
One of the first lessons I was taught when training to pilot VLCC’s onto Single Buoy Moorings in Nigeria was the importance of checking that the helmsman put the wheel over as ordered Read the rest of this entry »
MAIB Report: Elbe Collision & Grounding
MAIB Report: Collision on the Elbe off Brunsbuttel Lock.
Vessels: Sunny Blossom, Arctic Ocean, Maritime Lady
Last December the MAIB released a report into a collision, subsequent sinking followed by another collision of the entrance to the Kiel Kanal off Brunsbuttel, all under the Elbe VTS control tower. Read the rest of this entry »
119th Conference 2006
CONFERENCE 2006
2006 saw delegates back in sunny Eastbourne for the 119th annual conference at the T&G centre. The following is a brief account of proceedings but the minutes of the proceedings will shortly be uploaded onto the members’ area of the UKMPA website along with the presentations made. Read the rest of this entry »
E- Navigation
E-NAVIGATION:
WHERE ARE WE AND WHERE ARE WE GOING?
The term e-Navigation first appeared formally just one year ago in a presentation given by Dr. Sally Basker of the General Lighthouse Authority (GLA) and was rapidly adopted by our own DfT who introduced it to a wider audience via a keynote speech to the Royal Institute of Navigation given by Dr. Stephen Ladyman, the shipping minister.
View the original illustrated pdf magazine article (Page 2):
pilotmag.co.uk/userfiles/Pilotmag%20287%20(Oct%2006).pdf
WHY IS IT NEEDED?
To minimise navigational errors, protect people and the environment, improve security and reduce costs for shipping.
HOW WILL IT BE DELIVERED?
By using satellite positioning systems underpinned by fail safe supplementary positioning systems displayed in an intelligible and comprehensively integrated format on board ship and replicated on shore with shore based monitoring and intervention capability.
WHAT DOES IT MEAN?
This is a very good question since as the expression gains momentum there are different interpretations emerging! However, at the time of writing the definition which has been adopted by IALA is:
“the collection, integration and display of maritime information onboard and ashore by electronic means to enhance berth-to-berth navigation and related services, safety and security at sea and protection of the marine environment.”
WHERE DO WE GO FROM HERE?
At a recent IALA conference on e-Navigation it was stated that the following requirements would need to be met before the concept could be implemented effectively:
· Key structural components, including Electronic Navigation Charts (ENCs), principle position systems (GPS, Galileo) and failsafe back-up systems
· Standardised electronic format for ship/shore; ship/ship; shore/ship
· Means to prioritise data
· Enhanced Electronic Chart (ENC) systems
· Common standards for bridge/shore e-navigation systems / standards.
· Security through effective protocols
· Shore support systems linked nationally and internationally similar to air traffic control.
· Close collaboration with all relevant bodies and agencies.
With a view to achieving the above, a paper has been submitted to IMO proposing that e-Navigation be added to the work programme of the Sub-Committee of Navigation (NAV). However the IMO is still debating the implications of the concept and although it is likely that the carriage of an Electronic Chart display and Information System (ECDIS) or Electronic Navigation Chart (ENC) for all merchant vessels will become compulsory in the next few years the last meeting of the IMO Navigation sub committee (NAV 52) failed to endorse the overlay of additional information such as ARPA plots and AIS onto the ECDIS display. This decision has reigned in some of the more enthusiastic promoters of e-Navigation who see the future concentrated on ECDIS displaying “virtual” navigation aids and reflects the opinion that too much emphasis is being placed on unproven electronic data formats at the expense of proven traditional navigation methodology. IMO secretary-general Efthimios Mitropoulos believes that the ultimate aim of a future e-navigation strategy should be ‘to simplify, to the benefit of the mariner, the display of the real-time environment in which his or her ship navigates. Furthermore, the design of an all-embracing electronic system on the ship bridge should be such as not to reduce the navigator solely to the role of monitoring its function but ‘to enable him or her to obtain maximum navigational support and information to facilitate and ensure appropriate and timely navigational and anti-collision decision-making, in line with good seamanship.’ These are wise words indeed and very relevant given the statistics that despite the introduction of new navigation equipment the number of collisions and groundings remain unacceptably high even on board modern ships fitted with electronic charts. Bolting on an ECDIS displaying “virtual” navigation aids is not going to miraculously reduce the ship loss statistics without standardised displays and controls and a comprehensive training regime to enable watchkeepers to effectively integrate and interact within the e-Navigation concept. As pilots we are trained to integrate into the ship’s navigation regime frequently in total darkness and always within a very short time scale. This makes us ideal commentators on how appallingly inefficient the vast majority of ship’s bridges are. It is therefore worth examining in more detail the environment in which we and the average watch keeper operates.
BRIDGE LAYOUT
In order for the e-Navigation concept to be implemented effectively wheelhouse design will be of paramount importance. The glossy brochures display wonderful photographs of integrated bridges consisting of consoles containing radar and ECDIS displays and whilst these do exist on board some vessels the reality for the majority of ships is totally removed from this brochure image. Picture 3 shows the wheelhouse of a large bulk carrier built in 2005. Any navigating officer transported from the 1960’s onto this bridge would find it totally familiar! The traditional telegraph is on the port side, a helmsman’s / autopilot console is in the middle and two radars are to starboard. There are two VHF sets, one on each side of the bridge front and the chart room containing the GPS and AIS displays is to the rear of the radars where is can be screened off by a traditional curtain arrangement at night. There is absolutely nothing wrong with this wheelhouse so far as navigating in the traditional manner is concerned but for e-Navigation functionality it fails miserably!
The “ideal” integrated bridge is well illustrated in picture 4 which was taken on board a brand new 5000 tonne product tanker. When seated the watchkeeper has all relevant information readily available. The radar, ECDIS, echo sounder, autopilot and VHF are all to hand, although the crew had not yet got around to making and fitting the essential coffee mug holder! From the seated position the eye line of sight is above the console thus retaining the essential concept of a visual lookout. Constructed for the N Europe trade the vessel is fitted with two fully authorised independent ECDIS and had no paper charts and docking stations on each bridge wing made berthing / unberthing efficient. The vast majority of ships bridges fall somewhere between these two examples but many are very poor and not fit for purpose. The “integrated” bridge shown in picture 5 was taken on a 1000 tonne coaster and is a prime example of a poor layout. The chair is so low that when seated the watchkeeper can only see the radar and gyro repeater and has almost no view of the sea ahead! The autopilot and VHF are not easily reached and the chart table is to the rear so the e-Navigation concept is not going to be readily incorporated on this or the vast majority of vessels without a complete re-fit of the ship’s bridges and equipment.
THE EQUIPMENT
Compared to the airline and now even the road transport industries the navigational equipment to be found on the world’s merchant fleet is an appalling mix of units of generally poor quality frequently designed to satisfy the creative ideals of the manufacturer with little regard for the operational prioritisation needs of the end user. This woeful state of affairs was highlighted in Dr. Ladyman’s RIN speech where he stated, “… the bridge of a typical merchant ship is awash with different generations of navigation technologies – which are not always complementary. The display equipment isn’t integrated or prioritised. Value added data management is either limited or nonexistent. And what information is available, visual or otherwise, needs careful interpretation by experienced professionals. In short, mariners are asked to navigate with a variety of ‘bolt-ons’ to previous generations of technology.”
Starting from this level it is obvious that e-Navigation is not going to take over the world of merchant shipping for some considerable time!!
RADAR
In the 1960’s the the maritime press dealt with how radar should be incorporated into the watchkeeper’s duties and there was one point upon which all correspondents were agreed and that was that there should be universally standard layouts and controls. But by the time the specifications had been through the “consultation process” the only standardisation was on the basic controls and labelling. Once the sets became more sophisticated during the 1970’s with gyro inputs, true motion displays and Automatic Radar Plotting Aids (ARPA) any standardisation went overboard as manufacturers tried to outdo each other with additional features. The basic controls of the early models gave way to increasingly complex keyboard layouts which in turn evolved into the rollerball and button arrangement which requires every function to be accessed by the frustrating task of manipulating a cursor around the screen with many essential features hidden in sub menus resulting in a watchkeeper having to spend a considerable time learning how to undertake even quite basic operations. With crew changes frequently being done in just a few hours and the minimum manning resulting in officers being put to work on cargo and other duties the operation of key navigation equipment is often neglected and the manuals are generally too big and poorly written. I have frequently asked a watchkeeper to access a function on the radar only to be informed that he had only just joined the ship and hadn’t a clue! On one model I have found the range rings hidden in a secondary sub menu and it is generally just not worth bothering to even attempt to set up a parallel index tracking line with a rollerball and button control if sanity is to be retained!
New radars fitted after July 2008 will have to be fitted with an AIS overlay facility which is already appearing on board many vessels but these regularly display a considerable discrepancy between the radar and AIS plots as shown in picture 6. This AIS integration has even more worrying consequences in that currently there is no requirement for vessels (other than high speed craft) of less that 10,000grt to be fitted with an ARPA facility on the radar, so this means that there will be a tendency to use the AIS track for anti-collision work. There is a recommendation that only water tracking should be used for anti- collision work but AIS displays true Speed Over the Ground (SOG) and Course Over the Ground (COG) and AIS is not yet recognised as a collision avoidance procedure in the COLREGS. Consequently despite its imminent compulsory incorporation, many ship owners such as Maersk are instructing their Masters not to use the AIS overlay facility on the radar! To call the current situation a mess is a very polite understatement!!
ECDIS & ENC
For those unfamiliar with the terms, an ENC is basically a paper chart which has been scanned into an electronic format to be displayed on a computer and is termed a “raster” chart. Zooming in or out just magnifies or reduces the data from the chosen chart. An ECDIS is a “vector” chart format with layers so starting from a small scale only the basic outline information is displayed but zooming in reveals more features such as buoys, increased number of depth soundings, nature of bottom etc. A full ECDIS can therefore be interactive in that the navigator can program in depth parameters and if the ship is heading towards a danger then alarms will sound. It is this type of chart that can be used to replace a paper chart portfolio. Although vessels have been able to replace their charts with an authorised ECDIS system for over two years I have only piloted three vessels without paper charts which is less than 1%. The number of vessels fitted with a raster ENC is higher at around 25%.
Many observers are questioning why the uptake of electronic charts has been so slow. The answer is straightforward, it is not compulsory and in their present format many electronic charts are useless for practical navigation! A paper chart is a large document that can be opened out and the navigator can use a small scale chart for an overview of a proposed passage and easily plot a passage which can then be transferred to larger scale charts as required. This is safe and effective. The average electronic chart display is a 17 inch monitor so even plotting a short course is a challenge. A rough line can be created but then the navigator has to zoom in and scroll from screen to screen to verify that the course safely clears dangers which may not be displayed on the smaller scale chart. I have witnessed a watchkeeper totally distracted during a major part of the piloted passage whilst he attempted to plot a passage through the islands in the Baltic on an electronic chart and cursing the fact that he had no paper charts to plan on. An increasing number of companies are addressing this problem by publishing passage waypoints. This appears to be just what every navigator needs except that in the vastness of the open sea an increasing number of ships are now plotting their courses using published waypoints and the result has been an increasing number of collisions in the vicinity of these waypoints! The restricted screen size results in a raster chart displaying so many depth soundings that it is often difficult to see the charted features clearly. Zooming in on a larger scale chart will clarify the picture but then the distance shown ahead may then be less than two miles. Even worse is that on some makes of ENC the ship transits the screen in true motion thus providing an excellent record of where the ship has been rather than where it is going! One final major factor influencing ENC take up rates is that of after sales support. I have piloted several well equipped ships with a fine electronic chart which is out of date because the manufacturer has gone out of business. As with radars the manufacture and supply of electronic charts will inevitably end up in the hands of a few large companies and it is therefore understandable that owners will want to ensure that their chart supplier will be able to offer full support before making what is a considerable investment.
PRACTICAL USAGE
At a glance, the navigator can see his vessel superimposed on the chart with all the navigation marks readily identifiable but the vast majority of the ENCs in use are not official ECDIS and therefore come with a warning that they are NOT to be used for navigation! Of course this warning is invariably ignored and an investigation into a recent grounding revealed that the Master was navigating on an out of date electronic chart that he had downloaded from the Internet. Another grounding of a prestigious cruise liner resulted from the failure of the GPS connection which caused the ENC to default to dead reckoning position mode. The GPS failure went unnoticed for two days and no checks were made by other navigation methods until the vessel came to an abrupt stop! It would seem that the presence of an ENC seems to lull the watchkeepers into a false sense of security and to overcome this torpor it would be very simple for the manufacturers to incorporate a flashing warning on the screen when the GPS signal is lost or weak that couldn’t be removed until the problem had been resolved.
Earlier I mentioned the new tanker with an ECDIS in place of paper charts. With two independent units served by separate DGPS receivers, failure of both units simultaneously is unlikely and therefore in practical terms position failure will only occur if the satellite network is disabled. However ECDIS chart coverage is currently far from complete and chartless ships are therefore restricted to certain areas such as North Europe and parts of the USA. On this particular vessel the ECDIS was spot on at the commencement of the passage but later on serious anomalies were observed when the radar and AIS vectors of other vessels were overlaid on the ECDIS. Pictures 7 & 8 are very revealing in that they show how a discrepancy can introduce an element of doubt into the situational awareness. Picture 7 is displaying the AIS and ARPA track of a vessel passing a buoy so which side of the buoy did the vessel pass? The visibility was good so I could see that the AIS track was the correct one but in reduced visibility there would be confusion and doubt. Picture 8 reveals another confusing situation. Here the AIS and two radars are sending tracks onto the ECDIS, none are aligned. A check with a fixed navigation mark revealed that during the passage the radar and ECDIS correlation had become displaced by around one cable. The “tech-savvy” Russian Mate stated that he could re-align the displays but this shouldn’t be necessary and the error highlights how the integration of navigation displays has not yet been perfected and could lead to an incorrect interpretation of a developing situation. Since ECDIS will be a core component of e-Navigation in my opinion such serious errors call into question the whole concept.
AIS
The compulsory carriage of AIS was pushed through at far too great a speed for the system to be properly incorporated as part of the ship’s navigation equipment and consequently on the vast majority of ships it is just another box which is placed on any spare space on the bridge. Generally it is only used when the watchkeeper wants to identify another vessel so that he can call it up on VHF and negotiate a developing situation rather than rely on the COLREGS! One reason for the acceleration of AIS implementation was the USA’s anti terror policy which under its Maritime Domain Awareness programme is seeking to track and monitor every vessel bound for the USA from loading port to destination. AIS is part of the development of a Long Range Identification and Tracking (LRIT) network currently being progressed through IMO into a SOLAS requirement and AIS & LRIT represent the other key element of the e-Navigation agenda. The e-navigation implementation process is now being driven by the perceived needs of shore administrations rather than an actual need by the mariner who, as usual, has been sidelined from the debate. Fortunately pilots have attended the relevant IMO sessions and have at least been able to speak with considerable authority on the issues as a result of their involvement in the Maritime Navigation and Information Services (MarNIS) project which is explained in detail on page 7.
Prior to the USA security agenda the primary promoters of AIS were the ports who saw AIS as the key to the “Holy Grail” of Vessel Traffic Service (VTS) control of shipping replacing pilots. However, although effective when functioning correctly, AIS useage has revealed many shortfalls and if, as envisaged, its role is enhanced to underpin the e-Navigation agenda then more problems can be anticipated. Many of the AIS issues have been well documented in previous issues of The Pilot.
VESSEL TRAFFIC SERVICES (VTS)
Proponents of VTS see shore-based operators replacing pilots on board ships by offering e-Navigation control of shipping and the preferred terminology is now Vessel Traffic Management Systems (VTMS). For years many voices, ignorant of how shipping movements in port are handled by pilots, have questioned why shipping cannot be controlled in the same manner as aircraft are by air traffic control. The arguments put by pilots as to why ATC methodology cannot be applied to shipping have been supported by trials which always reveal that positive control of shipping by shore is non viable. AIS and the e-Navigation concept has revived the agenda but whilst it is true that modern VTS centres have far more sophisticated tracking ability, the complexities of varying ship types, speeds and tracks still prevent the VTS from being capable of positive control of shipping.
To date VTS hasn’t had a great success rate in preventing collisions and groundings as dramatically revealed by the Karen Danielson collision with the Great Belt West Bridge and is also interesting to note that because VTS is currently just an aid to navigation MAIB investigations into incidents in ports operating VTS have concentrated on the actions of the vessels but not the VTS involvement. Obviously, if VTMS is to evolve to take direct control of vessel movements then the liability issues will need to be carefully examined by the VTMS authority who will also need to bear in mind that its role in any incident will be examined by investigators. The arguments for and against VTMS are many and varied and worthy of a full feature but suffice to say at this stage that no system is currently capable of reproducing the real time situational awareness and vessel control available to the pilot or Master on the bridge.
PORT APPROACH DOCKING SUPPORT SYSTEM (POADSS)
Pilots cannot remain detached from new technology and within Europe, as part of the MarNIS project, EMPA have been project leaders on the finely named POADSS concept which has evolved from the IPPA project. POADSS is basically a laptop with very high specification for information input and accuracy designed to be taken on board by a pilot. The first units are due to be trialled next spring and the pilot will be able to access and prioritise data and information relevant to the pilotage passage. With nearly all data available to the VTS accessible directly by the pilot I believe that the logical progression for PODSS should be towards port control becoming “silent VTS” data processing centres. This may seem a provocative pilot biased statement but in my opinion an independent analysis of what information is transmitted by VTS and how it is used by those on board would find that most of the information could be accessed / disseminated directly from source to user.
For example, in London live tide data is broadcast every half hour but often vessels call for updates between broadcasts to check on how the tide is making. The relevant tide gauges are transmitting data continuously so it would be far more efficient if the pilot were able to interrogate the gauge directly. Another example is requesting a change in berthing time. Through POADSS a pilot could interrogate the berth to find out if it is free or what time the vessel on the berth is programmed to depart and then send an ETA either to the agent or directly to the berth, boatmen and tugs etc.
These are just two examples but the vast majority of data and information handled by VTS could be accessed and transmitted directly between facilities and ships.
Obviously ports need to monitor and record the traffic in their area but I believe that a port VTS centre designed to handle and process a port’s administrative function rather than seeking to become involved in the on-board navigation process would evolve into a different management and layout of VTS centres than currently exists.
CONCLUSION
A basic factor of e-Navigation is that it is administration-driven, not user-driven and the users do not particularly need or want it! In order to be fully operational and fulfil the aims of its promoters it needs:
· Worldwide ECDIS coverage.
· Worldwide GNSS coverage.
· Worldwide communication equivalent to
- Broadband for every SOLAS vessel.
This latter communications link will require its own constellation of satellites (opinion stated by the Comite International Radio-Maritime) which won’t be cheap. Currently there are a series of conferences and seminars being devoted to e-Navigation and I hope to bring some feedback from these in a future issue. Meanwhile it is interesting to note that a powerful driving force behind e-Navigation is our own DfT who believe that that it should be planned and implemented in a coherent way. Unfortunately the rapid and diverse development in technology is now producing a flood of low cost equipment of variable quality, performance and utility onto the market which may actually worsen navigational safety. This factor has led most maritime experts to the conclusion that the implementation of e-Navigation is a very long way off indeed.
RCH AND
CONS
Automatic Mooring Systems
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 19th 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 21st 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
AIS Update
Automatic Identification System (AIS)
TRANSPONDER UPDATE
It is now just over one year since AIS became mandatory for all SOLAS vessel over 300 grt and although I must admi that my prediction that the system would have difficulty in coping with the amount f traffic in port areas has been largely proven wrong there are increasing cases of ships’ units failing in a variety of functions. These failures are about to gain in significance as a result of the implementation of Class B AIS for non SOLAS vessels and, from 1st July 2008, the requirement for new radars to have AIS integration. It is therefore timely to identify some of the problems that are occurring with the existing systems
View the original pdf illustrated article from the magazine:
pilotmag.co.uk/userfiles/Pilotmag%20285%20(Apr%2006).pdf
I am aware of three cases where total failure has resulted in vessels having to either send
their units away for repair or having to install a replacement set. This has meant that until
the AIS was repaired or replaced the vessels concerned were navigating without AIS and
were thus invisible to AIS tracking systems. With respect to other failures the most
common on-board malfunction is the misalignment between the gyro heading and the AIS
heading which results in the AIS heading either defaulting to North or the AIS heading
being incorrectly aligned. In the latter case this sometimes results from the unit being
switched off in port and if the heading is different when the unit is switched on again it
does not automatically align with the correct heading but defaults to north or retains the
original shut down heading. Unfortunately, such faults are not readily apparent to those
on board and are usually only identified by reports from other vessels or a VTS centre.
Fixing this alignment problem is also not straightforward on many vessels and I have
recently piloted a vessel where it was necessary to contact a service technician to resolve
this error. As experience is gained then these faults should normally be eliminated by
including the AIS gyro heading alignment on the pre sailing check list, but there is now a
new problem with this in that since the only training that most officers have received is
from the installation engineer, when new crews join who are unfamiliar with a particular
AIS unit they may have no idea how to undertake some operational procedures. This may
seem an unlikely scenario, but I was on one vessel recently which was reported as having
misaligned heading data and the gyro alignment interface was a via a small separate unit
with an adjustment dial tucked away underneath the wheelhouse console. Fortunately the
Mate had witnessed the installation, but this is not the sort of detail that would normally be passed on during the usual few hours of a crew change! All this of course does raise the point that surely in the 21st century, technology should be able to eliminate such tedious and fiddly operations! Another problem which I have observed on some ships’ AIS is he phenomena whereby AIS data either disappears (picture 1) or the data defaults to the basic MMSI number. Because these effects are not universal (other vessels and VTS are tracking the “missing” target without problems) I have been advised that such
target corruption is most likely to be caused by poorly installed equipment. However, and this is a problem that may become serious with the introduction of the Class B AIS, such target loss could also be caused by what is termed as “garbling” of the signal. It is therefore of relevance to be aware as to how garbling may ,ise and the following explanation is from a paper presented to the Royal Institute of Navigation NAV05 Conference by Dr Andy Norris who chairs the Technical Committee of the International
Electrotechnical Committee (IEC) that is responsible for issuing technical standards for ships’ radio and navigation equipment: AIS works on Time Division Multiple Access (TDMA) transmissions. The basis of TDMA is that time is divided up into
discrete ‘slots’ and only one station (base-station, ship-station, etc) will be transmitting during a particular time slot. For AIS there are 2,250 slots in every minute on each of the two AIS VHF channels, which are known as AIS 1 and AIS 2. UTC is used as the time
reference. When an AIS Class A station is first switched on it predetermines its transmission slots by ‘listening’ to the existing traffic. This establishes which slots are free, helped by stations already ‘on-air’, which broadcast their future slot selection as part of their transmitted messages. The fact that each station determines its own slots within an organised regime gives this technique the name ‘Self Organising TDMA’ (SOTDMA). In busy areas unused slots become rare and then stations select slots already in use by the most distant stations. These are readily calculated because of the positional data contained within the AIS messages. The organised reuse of slots from distant stations should make AIS degrade “gracefully” as the number of stations in an area increases by making the effective range of AIS decrease to match the increase in station density. The characteristics of the frequency modulated (FM) signal used by AIS helps in ensuring that the strong signals from close stations are properly demodulated in the presence of weaker signals from more distant stations sharing the same slot. This is known as co-channel interference rejection. However, if confronted with signals of similar strength the demodulator becomes confused and ‘garbling” occurs. In fact there are a number of mechanisms that can make signals from distant stations similar in strength or even stronger than some closer stations. For instance, poorly situated AIS antennas can cause ‘masking’ in some directions and enhanced sensitivity in other directions. Also, anomalous propagation of VHF signals during particular climatic conditions can provide a focusing effect, giving even very distant stations unusual prominence. For these reasons the inbuilt features of SOTDMA do not always ensure that closer stations are received in preference to more distant stations.
Practical Useage
With respect to the type of equipment installed, the overwhelming majority of vessels are fitted with the minimum required to comply with carriage regulations! These are small alpha numeric displays which at the absolute basic level have to display at least three targets. I have seen such minimal three line units on ships and for all practical purposes they are totally useless. Other systems cram a list of many targets into the small display (typically 9cm x 12cm) which renders them illegible and again these are totally useless. The more sophisticated units, such as those manufactured by SAAB and SAILOR, are fortunately the ones most commonly fitted but due to the small screen size these also have severe practical limitations in areas where several ships are present, which of course is when it is likely to be of most benefit! These intermediate sets offer a choice of display modes, with either a list of targets being displayed or a by a graphic display similar to a mini radar picture. On the graphic display (picture 2), selecting a target for display is so fiddly that again it is impractical and in my experience around 90% of vessels have the display set to the list mode. Again there are several options for listing but the most useful is
the target list selected by range (picture 3) which displays the MMSI number, the name of the vessel and its range and bearing. By scrolling down the list a target can be selected and extended data on the selected vessel can be obtained (picture 4). The obvious place for sighting such displays is adjacent to the radar where the bearing and rage of a radar target can be correlated with the AIS display and a good example is shown in picture 5. However, on many vessels the AIS is sited wherever there happened to be some space when the set was delivered and this is usually remote from the radar and quite frequently in a corner at the back of the chart table! I have yet to come across any free standing AIS unit that has an integrated anti collision warning fitted should another AIS target enter a pre determined danger zone around the own vessel, although such alarms are usually present where AIS is integrated into the radar display.
Integrated AIS on radar
The integration of AIS onto the radar display is being received with mixed enthusiasm by those on board using such systems and much depends on the quality of the equipment and its installation. Picture 6 shows a high quality display which provided very accurate tracking with good correlation between the radar and AIS vectoring although even this equipment revealed some offset between the radar and AIS targets (picture 7) and on other sets I have observed offsets of up to 5 cables and this is one aspect of integration which may cause a watch keeper to make an erroneous interpretation of a developing situation. Another particularly annoying “feature” of some AIS / radar integration displays is that although the AIS function can be switched off, many such displays that I have come across have had an automatic AIS proximity alarm which triggers if another AIS vessel enters the radar’s anti collision guard zone. One unforeseen result of this supposed safety feature is that even when approaching a vessel at anchor or moored alongside, the AIS “collision” alarm resounds around the wheelhouse! The solution? The guard zone is set to zero and the alarms are set to “mute” thus neatly disabling one of the primary anti collision functions of the radar!!
One other fact is that I have yet to come across any Master or Officer of the Watch (OOW) who has been on an AIS course or received any formal instructions in its use. All knowledge on board has therefore either been gained from a brief introduction from the
installation engineer or from the user manual. I believe (although I hope that I am proven wrong again!) that this lack of formal training is going to be a significant factor in vessel safety as Class B units and AIS radar integration displays are introduced. These two developments are designed to provide “additional information to the OOW to enhance the situational awareness of a developing situation with respect to collision avoidance”. This all sounds admirable but the limitations which have been placed on Class B AIS mean that both SOLAS and non SOLAS vessels may receive incomplete and inaccurate data! The reason for this is in the technical specifications of the Class B equipment and again the following is an edited extract from an article on AIS B implementation written by Dr Norris for the “Digital Ship” online magazine.
AIS B offers leisure and other small vessel users a potentially valuable tool to enhance maritime safety at an affordable price. It has been designed to minimise degradation of the AIS network and will be available in three options.
_ The basic unit is a display-less transmitter for up-mast mounting to alert the vessel’s presence on SOLAS vessels’ AIS in the same manner as a radar reflector does now on radar.
_ Intermediate units have an inbuilt display (similar to the Class A displays) which, as well as broadcasting ownship position, will enable users to see the positions and vessel data of all AIS-fitted vessels in their vicinity on the display.
_ At the top end of the market AIS overlay capability will be added to radars and electronic chart systems, giving sophisticated navigational information to the user, vying with the facilities available on the most comprehensively fitted SOLAS vessel.
With this prospect of eventual high usage in the leisure sector it is worthwhile taking a look at some of the possible issues that may arise with this increased use of AIS.
The Class B transponder transmits at a lower power (2 watts) than Class A (12.5 watts) thus reducing the effective range of Class B transmissions and their effect on the network. Also, position reports are given at a maximum rate of once every 30 seconds, as opposed to Class A systems, which typically transmit once every 10 seconds and up to every 2 seconds. Importantly, Class B systems will give priority to Class A transmissions, delaying their own transmissions if a Class A station is already transmitting. This is the fundamental aspect of the Carrier Sense (CS) mode of operation that is used by Class B. Tests have confirmed that the AIS network is minimally affected even if there are relatively large numbers of Class B vessels in any area.
Collision avoidance
AIS is considered to be a useful aid to improve situational awareness but its use as an anti-collision device is not recognised by the IMO.
The Collision Regulations (COLREGS) are written around the concepts of visibility (sight) of vessels and the proper use of radar and have not yet been revised to incorporate any reference to AIS. However, Rule 5 of the COLREGS (Lookout) does emphasise the use of ‘all available means’ to make a full appraisal of the situation and of the risk of collision. It therefore appears that this rule requires vessels that have AIS fitted to use the system as part of such an appraisal, but not to take collision avoidance decisions based solely on AIS data. What is fundamental is that AIS data should only be used with the full knowledge that data errors are possible and that not all targets may be transmitting data - an AIS system may not be fitted or a fault may have developed.
AIS displays
It is of extreme importance to the Class B user to be aware that there is no statutory requirement for SOLAS vessels to be able to display AIS targets on a screen merely a requirement to provide a simple alphanumeric Minimum Keyboard and Display (MKD). To meet the minimum requirements this display need show no more than three ships at any one time detailing bearing, range and name of ship. Therefore Class B users must understand that their vessel may not be appearing as a ‘bright beacon’ on the displays of the majority of SOLAS vessels. Although IMO requires all new radars fitted after 1 July 2008 to have good AIS display capabilities, existing radars will not have to be upgraded and so it will be many years before AIS data can be effectively used for navigation on many SOLAS vessels.
Unfortunately, an uninformed Class B user with a reasonable AIS display may base their own collision avoidance decisions solely on AIS data thus creating significant problems for SOLAS vessels.
Information overload?
The confusing excess of data when navigating in waters crowded with Class B users will render AIS useless for most Class A users fitted with the MKD. On a radar screen an excessive number of AIS symbols will make the observation of raw radar data more difficult and so the display of AIS targets may need to be inhibited or an AIS target filter enabled. From July 2008 all new navigation displays capable of showing AIS targets will need to meet IMO performance standards which require that AIS filters must be included ‘in order to ensure that the clarity of the total presentation is not substantially impaired’. Increasingly sophisticated AIS filters may have to be developed but unfortunately it is difficult to make filters sufficiently adaptable to be effective whilst not obscuring possibly dangerous targets.
This article has highlighted some very relevant points and both the AIS B and radar AIS integration have the potential to create a dangerously confusing picture to the hapless navigator, especially in reduced visibility. I have previously identified a major problem
with AIS integration on radar and the addition of Class B AIS into the already crowded display has the potential to create a nightmare scenario. In view of the fact that data update transmissions AIS B vessels are going to be at least 30 seconds apart and in busy areas may not update at all means that the information will be historic and therefore totally unreliable and this, coupled with an automatic collision alarm function has the
potential to create so much information overload as to render the display unusable (picture 
. Dr Norris’ article refers to filtering but correctly identifies the problem of actual dangerous targets then being missed. Couple this with the fact that leisure users are
going to assume that they are being accurately plotted and carefully tracked by the professional navigators of the “bridge team” I don’t believe that the word nightmare is at all inappropriate! As if these factors are not sufficiently worrying there is a also move by IALA, buoyed by an enthusiasm for e-navigation by the shipping Minister and DfT, to introduced AIS based “virtual” navigation marks to replace the traditional physical marks! Considering that the original full implementation date for AIS by IMO was December 2008, which was accelerated by four years following pressure from the USA’s security agenda, I personally feel that the AIS has been implemented without a
proper assessment of the practical useage through structured operator feedback and to now release the system into the leisure market is sheer folly, not least because it is sure to tempt some leisure sailors to proceed in restricted visibility when they would normally remain in the marina. Just in case you may have any lingering doubts that I am exaggerating, there is already a British company called NASA Marine manufacturing an AIS receiver (note no transmitter included!) unit for the leisure market called “AIS radar”! The product description is as follows:
The Nasa Marine AIS radar is the first stand alone AIS receiver / plotter specifically designed for the leisure boat market. The display, with ranges of 1, 2, 4, 8,16 and 32 nautical miles shows AIS carrying vessels in a format normally associated with conventional radar. A trail of previous positions clearly chows the relative track of all the targets on the screen. A box to the right of the screen displays the speed over the ground, the vessel name, mmsi number and the latidude (sic) and longitude of any target selected by the user.
The Future?
The best installations that I have seen are where there is an Electronic Navigation Chart (ENC) display adjacent to the radar. The ENC automatically displays all AIS targets and is integrated with the radar so that any radar targets being plotted are also displayed on the chart. In this way the watch keeper can concentrate on using the radar equipment for which he should have been fully trained but can also refer to the ENC for an overview of the vesselís position and can monitor and obtain extended AIS information from this secondary system without interfering with the familiar radar detail which he has been trained to use. Unfortunately there are two major problems with this arrangement. Firstly there is no requirement to carry an ENC and secondly, in contrast to the still rare officially licensed Electronic Chart display and Information System (ECDIS) which can replace the paper chart folio, the vast majority of ENC’s currently in use do not meet the stringent specifications of an ECDIS for accuracy and corrections and come with the warning “Not to be used for navigation”! It is for this reason that radar has been chosen as the AIS screen display platform but I believe that with all the different radars incorporating the manufacturers (usually incorrect) ideas as to how information is accessed and presented to the user dangerous confusion will be the inevitable result of the rush to embrace AIS. However, I have been proven wrong so far so I am sure that I will be proven wrong again. I hope so!
JCB
My thanks to Dr. Andy Norris for his kind permission to use the texts included with this article.
Feedback Required
Feedback on experiences with all aspects of AIS are urgently required and reports should be sent to the dedicated “forum” link on the Nautical Institute website at: www.nautinst.org/ais/ Pilots are ideally placed to provide valuable input through their experiences on a wide range of ships in varying environments. All information received is passed on to the relevant experts who will use it to identify and resolve operational problems, so please participate. Serious errors should also be reported to the MCA on the form attached to MIN 231. Other MCA advice on AIS is contained within MGN 277 and MSN 1975.
Stolt Aspiration / Thorngarth
MT STOLT ASPIRATION / TUG THORNGARTH
MAIB REPORT
A consequence of changes to traditional tug operations has introduced new challenges for both tug masters and pilots. The increasing popularity of Azimuth Stern Drive (ASD) tugs has introduced a particular handling change since most of these tugs are designed with a bow towing winch resulting in towage over the bow. When on the stern or operating in the push/pull mode this does not cause too many problems but if required to operate on a centre lead the operation has increased risks of which pilots should be fully aware. On page 13 there is a review of the a monograph on this mode of towage published by the Nautical Institute and I would recommend that all pilots operating with tugs in this mode read this book in order to be aware of the risks and if possible also hold liaison meetings with the tug masters. When things go wrong operating in this mode the tug can rapidly lose control and the following is an edited extract from an MAIB report into one such incident.
Link to the original illustrated articlae (page 10):
pilotmag.co.uk/userfiles/Pilotmag%20285%20(Apr%2006).pdf
Stolt Aspiration, a 7901gt chemical tanker was bound for East Lewis Quay, Birkenhead. Entrance to the Birkenhead Docks is through the Alfred Lock The master and pilot had discussed the passage plan, and the pilot had signed the ship’s information sheet. Thorngarth, a Twin Azimuth Stern Drive (TASD) tug of 45t bollard pull, had been tasked with assisting Stolt Aspiration along with the tug Ashgarth. Both Thorngarth and Ashgarth were TASD tugs and towed over the bow. The two tug masters agreed that Thorngarth would act as the bow tug during the planned operation. Neither tug had any mechanical defects. As Stolt Aspiration approached Alfred Lock, the pilot began reducing speed steadily from 10 knots. The master of Thorngarth requested that Stolt Aspiration proceed at slow speed to allow the connection of the forward towline and, as this was normal practice, the pilot agreed. As the tugs approached, the pilot noted his speed through the water as 6.5 knots and slowing. Ashgarth reported that his line was being made fast and that he was happy with the speed. Thorngarth then began to make his approach. Because Thorngarth is designed to pass its towline from its bow, the tug had to approach Stolt Aspiration bow-to-bow, then manoeuvre stern-first to maintain the correct station off the larger vessel. The pilot was unhappy with the speed of Thorngarth’s approach, and warned the tug master. The tug slowed and the approach continued. Thereafter, Stolt Aspiration maintained a steady course, with the speed continuing to slowly reduce. Having received a heaving line from Stolt Aspiration, and having positioned close under the ship’s bow, Thorngarth backed away from her. The tug’s stern began to move to port, and this was corrected to maintain its position right ahead of the ship. However, the tug’s stern began to move to port again, which caused Thorngarth to move quickly across to the starboard side of Stolt Aspiration’s bow which, at this stage, was approximately 6 metres away from the tug. The tug master again attempted to position Thorngarth directly ahead of Stolt Aspiration’s bow, but this time, the corrective action caused the tug to move directly into the path of the vessel’s bulbous bow. Stolt Aspiration struck Thorngarth on its starboard side, causing the tug to heel heavily to port while being bodily displaced to port by the impact. On Stolt Aspiration, the pilot, noting the movement of Thorngarth’s masthead light, immediately ordered full astern, and used the bow thruster to counter the transverse thrust of the propellers and to maintain the vessel’s heading. Ashgarth also began to pull directly astern at full power to slow the ship. Thorngarth managed to pull clear and since she could no longer assist the ship was released and the Stolt Aspiration resumed the berthing operation without further incident.
Findings
The master of the Thorngarth had been appointed to the tug 10 days before the accident and had never carried out this manoeuvre on this tug and, although as mate he had seen it done on tugs of similar configuration, he was not fully familiar with the manoeuvring characteristics of Thorngarth. The collision occurred when the tug
master was re-positioning his tug ahead of the ship In backing away from the ship’s bow, the stern of the tug began to move to port. To correct this, he pushed the port ahead-astern handle forward, which swung the stern back to starboard. However, this slowed the tug and it closed the ship. Engine speed was increased to regain position ahead of
the ship. Once ahead of the ship, the stern again moved to port and again the port ahead/astern control handle was pushed forward to correct the swing. Because Thorngarth was now to starboard of Stolt Aspiration’s bow, as speed reduced due to
the change in astern power, she ended up on the starboard bow of Stolt Aspiration.
In attempting to recover from this position, the tug master caused Thorngarth to move across the closing bow of Stolt Aspiration where he was hit on the starboard side.
Tug manoeuvring controls and their propulsion systems cover a wide spectrum and, even among tugs of the same type, the speed of reaction of the propulsion gear to a control input will vary. As a consequence, any tug master will need to spend time familiarising himself with the controls of a new tug, even if he is familiar with the propulsion type and control system. Although the change of personnel between different types of tug is a necessary part of the flexible operation of a tug fleet, doing so without extensive initial or ongoing familiarisation training, where the complexities and nuances of control of different tug types can be properly understood and practised by the personnel concerned, will inevitably increase the risk of mistakes being made during operational situations. It was assumed that by the time an individual qualified as master, he would have experienced every type of tug manoeuvre, and that this experience would have been overseen by at least one other experienced master. No records were kept to monitor the training and experience gained.
OTHER INCIDENTS
Two similar accidents occurred elsewhere within the UK, within 4 months of the
collision between Thorngarth and Stolt Aspiration. In the first, a tug was operating
as the stern tug in moving a ship astern. After being asked to pull the ship’s stern to
one side, the tug found it could not regain its original position, and collided with the
ship’s stern. The second incident occurred when a tug, acting as the bow tug in a
berthing operation, was manoeuvring to pass its towline to the ship. Once the line
had been passed to the ship, the tug intended to move ahead of the ship, but collided with her bulbous bow. In neither case were there any injuries or pollution caused. In both cases, the tug masters had a wealth of experience in tug operations within their respective ports. However, both were operating tugs with unfamiliar propulsion systems and manoeuvring controls, and attempting manoeuvres with
which they were not entirely familiar. Safety issues identified as a result of the investigation.
1. Fatigue was not an issue in this accident.
2. There were no mechanical failures on either vessel that could have led to the collision.
3. The accident occurred when the tug master of Thorngarth was adjusting his position ahead of the ship and, due to his unfamiliarity with the tug, misjudged the amount of control movement required.
4. There was little that Stolt Aspiration’s crew could have done to prevent the collision.
5. Although the change of personnel from tug type to tug type is a necessary part of the flexible operation of a tug fleet, doing so without extensive initial or ongoing familiarisation training, where the complexities and nuances of control of different tug types can be properly understood and practised by the personnel concerned, will
inevitably increase the risk of mistakes being made during operational situations.
6. The bow-to-bow approach is conducted many times a day by tugs throughout the world.
7. No formal guidance was given to pilots concerning the capabilities and limitations of tugs in the port.
8. The introduction of new qualifications for Inshore Tug Operators has standardised the training requirements. The previous system was not satisfactory in that it relied on
personnel gaining the relevant experience over time but no records of experience gained were maintained.
9. The pilot and master of a ship would not know which type of tug has been allocated to the vessel until just before the planned operation. However, they could be confident that the tug would make the bollard pull requirement and would be capable of carrying out the designated task, despite not necessarily being the optimum choice of tug for the task.
10.There was no forum for the tug operators, pilots and port authority to raise matters of mutual concern.
11.By not informing the VTS operators of the accident, the VTS operators were unable to co-ordinate the response from the rescue services.
12.Two other accidents occurred elsewhere in the UK in a short period of time, both also caused when tug masters were operating tugs with unfamiliar propulsion systems and
manoeuvring controls, and attempting manoeuvres with which they were not entirely familiar.
RECOMMENDATIONS
The British Tug Owners Association is recommended to:
Encourage its members to ensure that the movement of personnel between tugs is
closely monitored, and that training and expertise of tugs’ crews are matched, and
are consistent with the type of tug and its expected task requirement.
Major Tug Operators, the British Tug Owners Association, and the PMSC Steering Group are jointly recommended to encourage regular formal discussion between port authorities, pilots and tug operators. All parties should be involved in the decision-making process, which will decide the optimum allocation of tugs for all manoeuvres within a port, and the level of crew experience required for each task.
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