Watching The Ships Go By

Liverpool, the River Mersey and Merseyside have interested me since my childhood visits. My first blog post was simply called Liverpool but there a quite a few now. You can find them all here (or click on 'Merseyside' in the 'Labels to select a blog topic' list). Although my home is some 80 miles from Liverpool, through the magic of the Internet I can "watch" shipping around Liverpool.

Wirralcam.org

'www.wirralcam.org' operate a number of webcams giving still pictures, generally updated twice a minute, from various locations on the Wirral. This offers an intriguing view of ships coming and going but, of course, doesn't provide information on the identity of the vessels or their itineraries.


Webcam view of the Mersey from Birkenhead Priory, with the twin towers of the Liver Building on the left and Albert Dock in the centre (Picture: wirralcam.org).

Automatic Identification System (AIS)

As an aid to maritime safety, most modern ships are fitted with Automatic Identification System (AIS) equipment, mandated by the International Maritime Organisation (IMO) under their Safety of Life at Sea (SOLAS) regulations. AIS installations on ships combine data regarding the ship's identity, destination, location as determined by GPS (Global Positioning System) equipment, together with heading and speed and transmit it periodically digitally by VHF (Very High Frequency) radio. The data is received and decoded by other ships in the vicinity and, where there is line-of-sight communication, also by various shore stations. Many ships also send and receive AIS data using Inmarsat communications satellites which (via satellite downlinks) makes the data available to ground stations lacking line-of-sight VHF communications with a ship. With digital communications and the internet, AIS data around the globe can be consolidated into vast databases of shipping movements. There's a Wikipedia article about AIS here. For a more detailed treatment, try the PDF of the recommendation covering AIS issued by the International Telecommunications Union (ITU) M.1371-1 here. I think the standard is now at M.1371-4 but the PDF linked should give an idea of the complexity of the requirements. Atlantic Source is a Spanish supplier of AIS and other communications equipment whose website may be of interest.

Maritime Mobile Service Identity (MMSI)

AIS equipment makes use of a vessel's unique Maritime Mobile Service Identity (MMSI) which is described in another Wikipedia article here. Note that whilst MMSI, heading, speed and position are automatically derived from ship sensors, some data like destination and status ('underway', 'at anchor') is manually entered by the bridge crew and is sometimes inaccurate, so don't be surprised if a ship supposedly at anchor is making 15 knots! Because the AIS data can be transmitted by VHF radio, drop-outs or temporarily erroneous data are also possible.

IMO identification number

Most merchant ships are allocated an IMO identification number, displayed on the vessel, intended to enhance "maritime safety, and pollution prevention and to facilitate the prevention of maritime fraud". There's a Wikipedia article here.

Commercially-accessible data

Commercial sites like 'Marinetraffic.com' and 'Vesselfinder.com' collect and analyse data transmitted by ships fitted with AIS and make certain information freely available (with other information hidden behind a 'paywall'). These sites have vessel details and photographs in addition to information about present position and previous voyages. You can search for a particular vessel by name, MMSI or IMO.

The ShipAIS site

To display AIS data for shipping around Liverpool at home, I like enthusiast-run site ShipAIS with its sub-title "Watching the boats go by" which offers excellent coverage of Liverpool and other areas. I tend to default to the Liverpool Docks page here (which will update every 2 minutes), switching to the geographically-adjacent Bar Racon or Mersey River pages as necessary. They have a useful Frequently Asked Questions page here (which has thoughtful comments about security concerns which have been raised about the wisdom of making shipping movement data widely available). The site can also display each vessel's MMSI number (which is unique), name (which may not be unique) and IMO identification number (where allocated). There may also be other data and a photograph of the vessel.

Remote Ship Watching

The ShipAIS page will show vessels in the area covered by the map and some of these may be visible on one or more Wirralcam.org cameras. Unrecognised ships or vessels of particular interest can be followed up using the free data on one of the commercial sites. I find the quickest is often to give Google the search string , for instance 'ship 235112573', which quickly finds various offerings for ACL's Ro-Ro/Container ship 'Atlantic Star' on sites like 'Marinetraffic.com' and 'Vesselfinder.com'. More technical information may be available on the shipping line site, for instance, ACL have more information on this '4th Generation CONRO vessel' here.

Improved ship safety

The ability to remotely watch ships I find impressive but, of course, the justification for all these systems is improved ship safety. The introduction of Radar and Radiotelephony were significant milestones but, on many modern ships, the integration of electronic charts, radar, GPS, AIS and information from various ship systems into what's called Electronic Chart Display and Information Systems (ECDIS) furnishes a whole new level of safety-related information which can automatically generate alerts to potential hazards. There's an introductory article about ECDIS on Wikipedia here. As mentioned in some of my travel posts, I've managed to visit the bridge of a few vessels equipped with ECDIS and been fascinated. I'll write a little more when I can.