GEAR TEST
66 http://www.yachtingmonthly.com MAY 2016Class-B AIS transceivers
T
housands of leisure
craft already have AIS
receivers. Now, however,
boat owners are realising
the importance of
being seen, as well as seeing
other vessels, and are fitting or
upgrading to an AIS transponder.
Technically it should be called a
transceiver, but the industry has
adopted ‘transponder’ as a fitting
description for AIS that transmits
and receives, so to avoid
confusion from here onwards
we’ll refer to them as such.
Because it’s so useful to overlay
AIS information on electronic
charts, we’ve mainly focused
on ‘black box’ AIS transpondersThe UK’s most trusted sailing gear tests
AIS transceivers are currently the most popular item of electronic safety kit being installed
on leisure yachts. Duncan Kent tests the features found on black-box ‘transponders’
that don’t have their own screens
and are designed to display data
on a chartplotter.What is AIS?
An AIS receiver or transponder
enables you to ‘see’ other vessels
on a plotter screen, along with
their characteristics (position,
SOG, COG and MMSI being
the most useful for collision
avoidance). They transmit and
receive on marine VHF Ch87B
(161.975MHz) and Ch88B
(162.025MHz). You can buy a
cheap receiver for around £100
that will let you see other vessels
operating an AIS transponder
within range (usually up to 15miles or so), or if you want your
own vessel to show up on their
display then you’ll need to install
an AIS transponder, along with its
own antenna and GPS.
Owing to the considerable
safety benefits, Class-A AIS was
made compulsory throughout the
World in 2002 for all passenger
ferries and vessels over 300GT.
Class-B AIS is for non-commercial
leisure craft and is optional on
boats under 24m LOA.
More recent developments
include the introduction of the
ATON (Aid to Navigation) beacon,
which shows as a diamond mark
on the display, as opposed to
the triangular vessel icon. This
beacon can be real (such as a
transmitter installed on a buoy or
lighthouse), or ‘virtual’ (simply an
AIS signal transmission, usually
from a land station, that contains
the position data of a ‘mark’ that
will show up on an electronic
chart as an actual mark).
The other icon seen these days
is a man overboard icon (a little
person holding up hands), whichHow we
tested them
The most common problem
we experienced when setting
up the units was getting the
device driver to load and
setting the COM port. These
days everything is supposed
to be ‘plug-and-play’, but it
most definitely isn’t.
Often, Microsoft Windows
doesn’t have the correct
driver in its archives, in which
case it won’t automatically
download. The driver will
either be supplied on a CD,
or you will need to download
it from the web. Then you’ll
need to open the device in the
control panel and manually
download the driver. As themethod varies depending on
which operating system you’re
using I can’t explain the process
in full detail here, but there is
plenty of advice online.
Lastly, ensure the software
is compatible with
your operating system.
For instance, the most
common AIS control
program is proAIS, which
only works with Windows
7, 8, 8.1, 10 (Microsoft), or
OSX (Apple).
We installed all the setson our testbed in Chichester
Harbour, using a separate, AIS-
tuned antenna and the GPS
antennae supplied. For those
supplied with an antenna
splitter, or with one built-in,
we also connected a Standard
Horizon radio to the unit to
check the splitter function
operated correctly.
All the transponders were
connected to a B&G Vulcan 7
chartplotter via our testbed
NMEA-2000 network, to check
out their receiver side. The
AIS transmission from each
unit was handled by another
receiver and plotter some
distance away.The units were all bench tested with an AIS-tuned antennaInstalling the software
drivers for each unit wasn’t
as simple as it could beAIS transponders help you
see other vessel and helps
them to see you tooPHOTOS: COLIN WORK