Introduction

Practical concerns of mariners, both those on-board ships and those assisting them from the shore, fall broadly into three areas.

Efficiency Safety Security. No single one of these can be emphasised at the cost of the others, and none of them can be ignored. Each is just as important as the others and they must all be considered whenever actions are taken, changes are made, and technology considered. They are inseparable.

Three inseparable items.

In this paper we will take a high level overview of some of the technologies available to port authorities to help them in each of these areas. This will, of necessity, be a somewhat personal view. The author has a Ph.D. in Pure Mathematics, a subject that some would say is not obviously useful, while others might even turn it around and say that it is quite obviously not useful! However, in working for Denbridge Marine Ltd over the past eight years it has become clear that the rather different and sometimes downright strange viewpoint this background affords has been of value in assessing the needs of both ports and pilots. While Denbridge's systems primarily provide VTMS capabilities for ports and offer assistance for the entire process from initial contact through to invoicing for services, their technologies have clear applications in all three of the major maritime concerns.

In an overview such as this, some parts of the document will, of necessity, cover material that is well-known to the reader. The author is well aware of this, and sometimes feels a little like he is explaining football to Beckham, or gravity to Newton. Such material is necessary, however, to ensure a consistency of treatment, and the reader's patience is appreciated.

A complete, in-depth analysis of all available technologies and their potential applications is well beyond the scope of this paper. If the reader has specific concerns, interests, suggestions or ideas then perhaps a subsequent paper could address them more fully.

The Three Concerns

As we stated above, the three main concerns are those of efficiency, safety and security. Before we can assess any technology against these issues we need some idea of what they mean and what they entail. Taking each in turn:

• Efficiency
  • A port must make money to survive. Without effective and efficient processes, too much time and therefore money can be wasted, dribbling away the already all too slim profit margins. Operations should take place once and only once, and must have a clear purpose. Any technology introduced to a port or vessel must not hinder its efficient operation.

• Safety
  • Working with large machinery inherently carries risks. These risks must be understood and minimised to ensure that staff and crew are protected against accidents. Technology that provides a more complete or accurate picture of the entire current situation can reduce risks in two ways. Firstly by the early highlighting of potentially dangerous situations, and secondly by ensuring that those dealing with a dangerous situation can assess the impact of their actions.

• Security
  • With large amounts of cargo and valuable equipment, ports and vessels must be protected against malicious acts, including:
    • Theft of both cargo and vessels (piracy)

    • Smuggling of both goods and people

    • Terrorism

    Technology can provide assistance here by the automated monitoring of complex situations and bringing to the attention of staff any anomalous situation.

• automating processes to improve their efficiency,

• providing more information in a comprehensive and easy to understand format, allowing people to do what they are trained for,

• automatically monitoring large amounts of data to find and highlight unusual events.

Available technology

For monitoring ports and vessels there are several sensors readily available. These include, but are not limited to:

• AIS / UAIS
• Raw radar
• Radio direction finders (DF)
• CCTV (including low light cameras)
• Sonar (both active and passive)

• Record data for subsequent playback and analysis
• Active monitoring, such as tracking or image analysis

We will now take a brief look at four specific technologies and consider their strengths and weaknesses

AIS / UAIS transponders

As an emerging technology, Automatic Identification Systems have given rise to a great deal of excitement, speculation, discussion and interest. The automated transmission of data such as name, call-sign, position, course, speed, origin, destination, cargo, vessel dimensions, etc., has clear positive implications for each of our three criteria.

• Efficiency
  • With vessel details being transmitted there should be no further need for the manual input of data. This eliminates the time taken and, more importantly, removes one source of errors in the system.

• Safety
  • With vessel position, course, and speed being transmitted there should be no problem in avoiding other vessels. The technology should ensure that every vessel in the area is identified and its DCPA (Distance at Closest Point of Approach) and TCPA (Time to Closest Point of Approach) calculated and assessed. Collisions should become a thing of the past.

  • Dangerous cargo situations can be identified early and appropriate measures automatically taken in a timely fashion.

• Security
  • With vessel details being transmitted regularly an automated system can check reports for consistency. Vessel reports can be checked against a central repository of ship movements to check that a vessel is who it claims to be, and unknown or unrecognised vessels can trigger a high alert state.

Raw Radar

Radar systems were a tremendous boon when first introduced and have to this day remained a critical part of many operational systems. The ability to locate vessels at large ranges and monitor their movements has avoided uncountable collisions and streamlined many operations. It must be recognised, however, that radar only approaches its full potential when combined with other information sources such as VHF radio traffic and AIS information.

Considering radar in the light of our three areas of concern we can see that there are few, if any, negative aspects to having a radar system. Perhaps the most obvious negative is the initial cost of a system. A financial outlay of tens of thousands of pounds is considerable, especially when taking into account the slim margins on which ports survive. The advantages are significant.

• Efficiency / Money
  • The question of efficiency is really one of saving money. The question then is clear - how can having a radar save a port money? The answer lies again in the integration of technology. In the event of an incident all too often no-one knows exactly what happened and there is little or no objective evidence of blame or fault. With a raw radar system an operator may have been watching the incident, or even tracking the vessels concerned. In this case fault can be assigned and fines levied against the appropriate parties. One such incident recovered the entire cost of a radar system within a week of installation.

    This become even more relevant when the raw radar has been recorded and can be analysed days or even weeks after the incident. More about that below.

• Safety
  • As yet not every vessel has AIS, and it will be many years before all vessels, including small pleasure craft, have such technology, if at all. Further, a vessel's AIS may be switched off or non-functioning. As a result a mariner cannot rely purely on the AIS to avoid collisions, and raw radar can and will continue to play a crucial role in safety both at sea and in port.

• Security
  • When raw radar is combined with other sensors, automated analysis of a situation can be used to highlight anomalous situations. Tracking on raw radar gives the option of raising an alarm when there is a radar plot without an associated transponder signal. If an AIS vessel travels in an area inconsistent with its reported details, or if the radar return is inconsistent with its reported size, again, the system can raise an alarm. Combined with DF, CCTV and sonar, raw radar provides an important tool in situation assessment.

Compression and Recording

Sampling radar at a bit-depth of 8 bits (256 levels) and at a rate of 50MHz, digitised radar comes at a price -- 50MBytes of data every second. Of course, this is an over-estimate because in order to avoid the "fold-over" phenomenon there is an enforced period of silence between azimuths. Further, many radar systems discard some resolution by sampling to a bit-depth of only 4 bits (16 levels). Even so, raw digitised radar comes at about 5 to 10 MBytes of data every second. Recording this is obviously impractical, and thus we use data compression.

Standard off-the-shelf lossless compression technology can provide a compression ratio of between 5:1 and 20:1 on radar images, leaving us with at least 250 KBytes/sec, or 21 GB of data per day, more than can easily be archived.

There are radar compression technologies, however, that can compress raw radar data down to rates of 38.4 KBits/sec or even lower. This data rate results in only 3GB of data per radar per week, an amount that can easily be stored, transferred and analysed. We can now assess this technology against our three concerns.

• Efficiency / Money
  • We return to the question of incident analysis and levying fines against those at fault. If the vessels involved in an incident didn't all have their AIS working, and if the operator wasn't tracking those vessels on their ARPA at the time of an incident, no evidence can exist. If the raw radar was recorded, however, the incident can be analysed in full after the event, including the tracking of vessels not previously monitored.

• Safety
  • At data rates of 19 KBits/sec we can transmit live raw radar pictures to portable radar displays. A ship's pilot can then have his own display that works completely independently of the ship's own radar system. More, the pilot has a display with which they are familiar and which is guaranteed to be in working order.

    Perhaps more importantly, the portable radar display can be configured to show a picture from a base radar station situated around the corner, showing an area of concern currently invisible to the ship's radar. Finally we have a "round-the-corner" radar capability. Transponder technology provides the same feature, of course, but it can only show the ships that are currently transmitting.

• Security
  • With live radar pictures being transmitted to remote displays we now have the capability of interceptor vessels with radar, and yet which remain radio silent. In some high-risk scenarios this could prove to be a telling advantage.

Conclusion

In an overview such as this can be few concrete conclusions. We do observe, however, that there is a recurring theme. Just as we must consider all three concerns, money, safety and security, so we must consider all technologies. It is the integrated approach that offers the most benefits, above and beyond the simple addition of features and facilities. Each technology can combine with each of the others to give new capabilities and new features. The question is not one of what is possible, but simply one of how much do you need.

Every ship is different, every port is different. Each must assess their own need for efficiency, safety and security. Our hope is that we've offered a fresh view on some old ideas, and an insight into some of the newer ones.

The Author

Colin Wright graduated with a B.Sc.(Hons) from Monash University in Melbourne, Australia, and has since obtained a Ph.D. from Cambridge, England, each in Pure Mathematics. He has worked for Denbridge Marine Ltd since 1993, specialising in raw radar data compression and vessel tracking technology, and can be reached by sending mailto:colin.wright@denbridgemarine.com

© C.D.Wright, Denbridge Marine Limited, 2002

Quotation from Tim Berners-Lee