DSC alerts
PLBS tests must be carried out in the first 10 minutes of the hour), but try to test at quiet times in quiet locations, and with the unit close to water level to minimise its broadcast range.
If in a high traffic area, call the coastguard and notify them of the MMSI numbers for each device you are testing, your location and the times you will be testing. If you are not able to reach the coastguard by radio then call them on the telephone.
Once activated each device transmits position, time, COG, SOG and a sentence identifying the unit as an MOB/SART. What is seen on the screen of any given receiver will depend on the receiver’s age. Most units now show the MOB symbol of a red circle with an ‘X’ in it, however older software may not and the MOB will show up as a normal vessel. Only the MMSI number starting 972 identifies the icon as a personal device. It is vital all crew know exactly what the AIS receiver will show when a device is activated.
Audible alarms for MOB alerts can be generated through various AIS viewers and receivers, however once again this depends on individual set ups. Many sets are capable of generating an audible alarm but only if a speaker is attached to the system. It is sometimes possible to tick the ‘audible alarm’ option, even if there is no speaker available so no sound will actually be made.
Especially if sailing shorthanded, an alarm is essential to the lifesaving potential of the AIS device. If you are not able to wire a speaker into your system consider getting an AIS device that incorporates a DSC alert, or running your AIS through a third party computer program via a laptop that already has an in-built speaker. For units incorporating DSC functionality, each device must be paired with the main VHF set on board. Pairing is usually done via a web page, either on a mobile phone or computer screen. Ensure you pair your device well ahead of time; you will need a good internet connection. Don’t forget to re-pair for every new vessel you sail on. Test the DSC function against your base station to check the programming has been accepted. Note that due to differing regulations pairing is not possible in all countries.
Devices will send a closed loop DSC alert to your base station, automatically on activation. An ‘all ships’ alert can also be sent either manually or automatically depending on the device. Read your instruction manuals carefully and from cover to cover. If there is a manual process to create an ‘all ships’ alert – write it down and remind yourself regularly. Make sure any new crew are well briefed on the manual process – this may mean opening up a jacket and looking at the device.
Battery life QUICK TIP
With all of this testing and pairing the batteries on an AIS device may take a bit of a hit. Manufacturers normally suggest a functional test no more than twice a year. If you are regularly changing crews and need to test more often don’t forget to regularly check the state of your battery. If you sail regularly with different crew and don’t want your jackets constantly opened and closed, get a spare device to demonstrate how to activate and check them.