Ship Plotter and the AIS Project ...

Living within 1Km of the sea and with a horizon of some 20Km on a clear day it's possible to view a variety of shipping as well as watching the local fishing fleets coming and going.

I stumbled across another weather site Meteo Málaga that as well as providing weather information for the south of Spain has a section for displaying the location and movement of shipping in the western Mediterranean areas of Malaga and Gibraltar. This sparked my interest as a potential new project for me to get my teeth into.

The first step was to download a copy of the ShipPlotter software from COAA, the Centro de Observação Astronómica no Algarve. ShipPlotter displays complete information about ships that are within VHF range of your position using the Universal Automatic Identification System (AIS).

AIS is a system that ships use to communicate their positions to each other as part of the global maritime safety system. From December 2004, all ships over 300 tons must carry an AIS system which broadcasts information about the ship to any suitably equipped receiver. AIS uses very short bursts of high-speed data on two VHF channels in the marine band. The two frequencies used are 161.975 (Marine Ch 87) and 162.025 (Ch 88) MHz. Ships broadcast their identity, position, course, speed and destination so that other ships can take account of their movements. Using a low cost radio scanner tuned to one or other of these channels and ShipPlotter software running on your PC, you will be able to see a radar-like real-time map (below) of all the large ships manoeuvring in your area together with information about their destination, estimated time of arrival and even the dimensions of each vessel.

The next step was to join the ShipPlotter User Group at Yahoo, which as with all user groups is a great source of knowledge and help.

The software program enables one to download information from a central database and display it on screen but the amount of information available for the Costa Azahar is fairly limited. So it is really essential to have a VHF radio to receive information directly from ships within range.

radio installation...

There are a number of radio receivers that are suitable for the task ranging from low cost VHF scanners to those designed specifically for AIS. After some consideration I opted for the Comar AIS-2-USB Receiver a low cost Dual Channel Parallel AIS Receiver specifically designed for use with a Laptop computer or PC. The Comar has two AIS receivers that monitor both AIS channels simultaneously and it is powered via the USB port.

For the receiving aerial I used an Opek MFV-5 Marine antenna that is designed to cover the marine VHF frequency bands with extended coverage to 162MHz. This was mounted on the roof of the house giving a clear line of sight to the horizon. I also added a Garex preamp close to the antenna in the cable downlead and this arrangement provides coverage to some 4,000 square kilometers.

peniscola sea area...

The chart above gives an indication of the depth of water off the Costa Azahar. A small point of interest are the five wells just within the 200 metre area. It's not unusual to see drilling platforms over these from time to time.

ShipPlotter User Guides

Colour EBook Download €5.00	B&W Paper Back €12.50	Colour Paper Back €39.99