Security In Shipping

Recent changes
Table of contents
Links to this page


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:

In short, technology can assist by

Available technology

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

In addition to these sensors we have the ability to

No single technique or technology completely addresses the three concerns listed above. It is the integration of systems that provides the most promising and exciting possibilities.

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.

There are also some clear negative implications, mostly due to the need for commercial confidentiality. Some companies will not want it widely advertised what their ship movements are and their exact ETA at a port. More obviously, the precise manifest will often have significant commercial implications, so it may be that the exact nature of a cargo is not transmitted. Likewise there may not be a central database of all ship locations against which to check incoming AIS reports. This will significantly reduce the potential of such technology. It remains an open question as to whether the full potential will ever be realised against such concerns.

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.

A critical aspect of sensor technology lies in the area of sensor fusion and presentation. We must at all times avoid overwhelming an operator, but still assess data consistency and highlight possible inconsistencies. Appropriate use of technology can assist greatly in reducing the burden on operators, while still increasing the effectiveness of the operation as a whole.

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.


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

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



Links on this page

Site hosted by Colin and Rachel Wright:
  • Maths, Design, Juggling, Computing,
  • Embroidery, Proof-reading,
  • and other clever stuff.

Suggest a change ( <-- What does this mean?) / Send me email
Front Page / All pages by date / Site overview / Top of page

Universally Browser Friendly     Quotation from
Tim Berners-Lee
    Valid HTML 3.2!