|MarineTraffic.net show vessels transmitting AIS signals.|
It's not everyday you purchase a product that comes with this dire warning.
|These commodities may not be used in the design, development, production of nuclear, chemical or biological weapons or missiles.|
I'm surprised Somalia is not on the list too, as undoubtedly pirates would find it easier to track vessels equipped with AIS, such as those captained by Captain Phillips (2013 movie
AIS, which stands for Automatic Identification System
, is an automatic tracking system used on vessels and land stations for identifying and locating vessels. An AIS receiver
detects the locations of vessels whereas a transceiver
additionally transmits the location of the given vessel. In order words, pirates only require a receiver, since they have no desire to broadcast their location. On the other hand, if you want
to be detected by other vessels, then a transceiver is what you need.
Being easily detectable, especially by the freighters that ply Gulf St Vincent and Backstairs Passage, is exactly
what I want. In keeping with (mostly) Raymarine electronic equipment on Arriba
, I chose the Raymarine AIS650 transceiver
. Somewhat annoyingly, the AIS650 comes with its own GPS receiver and GPS antenna, which means Arriba now has three
fixed-installation GPS receivers (not to mention handheld units).
Anyway, the transceiver transmits and receives AIS signals, which are data signals in the VHF frequency range, i.e., 30 MHz to 300 MHz, which are converted into NMEA messages. The NMEA messages go out onto the SeaTalkNG (NMEA2000) bus, and are interpreted and displayed by an electronic chart plotter, a.k.a. multi-function display (MFD). You have a choice of (1) installing a dedicated VHF antenna for your AIS or (2) installing a VHF splitter in order to use your existing antenna, the latter being the far more sensible choice. The splitter is a so-called active splitter
, meaning that it is smart enough to give priority to VHF radio voice and DSC traffic, over AIS traffic. In the loss of power, it falls back to being a straight-through wire so your VHF radio still works.
Note: Before you can configure your AIS, you will need a Maritime Mobile Service Identity (MMSI), which is a unique nine-digit code identifying your vessel that is obtained from your country’s Rescue Coordination Center (RCC). It is the same MMSI used for Digital Selective Calling (DSC). In the US, your MMSI must be pre-programmed by your retailer; you cannot do it yourself.
Here's the step-by-step AIS installation in photos:
PS The installation of the GPS antenna is documented in photos here
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