WatchMate 850 Class B AIS Transponder

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Practical Sailor Best Choice

'Best Choice' AIS Collision Avoidance Transponder!

In the September 2013 issue, Practical Sailor named the WatchMate 850 the 'Best Choice' for Collision Avoidance in a head-to-head test.

  • Designed especially for highest AIS performance and lowest power consumption.
  • Winner of two international innovation awards.
  • Nominated for the prestigious 2010 DAME Award.
Vesper Marine YouTube WatchMate WatchMate Anchor Watch Video
See how easy the Anchor Watch feature is to use

The AISWatchMate 850 Transponder incorporates a built-in GPS receiver and patch antenna with the award winning AISWatchMate collision avoidance display.

Using the Universal Shipborne Automatic Identification System (AIS) the AISWatchMate 850 Transponder transmits your AIS data and displays data from all AIS equipped vessels in your vicinity. Audible warning alarms are sounded if a potentially dangerous situation exists. The alarm sounds whenever a vessel is detected that will come dangerously close even though it may still be many miles away. You are alerted immediately with the closest point of approach (CPA) and the time until CPA.

Unique and customizable alarm and intelligent filter settings help to eliminate false alarms. Other vessels and alarms are displayed in a prioritized order assisting you to safely navigate in crowded shipping areas.

The WatchMate 850 is a fully self-contained Class B AIS transponder with GPS receiver and GPS patch antenna. It can be interfaced to other on-board electronics and will provide complete AIS output. However, it can be used totally stand-alone and it is not necessary to connect it to any other device.

Integrated AIS Transponder

Includes a built-in AIS Transponder with two channel parallel receiver and transmitter. This high performance transponder means greater range and increased safety. It also makes installation easier. No external "black boxes" to mount, power and wire. Just plug in a VHF antenna and connect the AISWatchMate 850 Transponder to your 12 or 24 volt power supply.

Class A, Class B and AIS SART & MOB

The perfect companion for AIS Search and Rescue and Man Over Board devices, including the latest models. Sounds the alarm whenever an AIS-SART or AIS-MOB is triggered. Clearly identifies them on the display and provides continuous position updates as well as bearing and range to the SART or MOB. See how this looks on the AISWatchMate here

Ultra-Low power consumption

Designed for minimal power consumption the AISWatchMate 850 Transponder is extremely well suited for energy conscious vessels.

Integrated GPS Antenna

Includes a built-in GPS patch antenna that provides GPS data to the integrated 50 channel GPS receiver. This internal patch antenna allows for simple installation. However if needed, an external GPS antenna connection is provided and an optional external antenna is available.

For best performance, the built-in GPS antenna requires a clear and unobstructed view of the sky. It usually works well when installed in a cockpit, under a non-metallic dodger or under a fiberglass hard-top. However, if you are mounting the AISWatchMate 850 Transponder in a location which does not provide adequate GPS signal coverage (eg. near or obstructed by metal objects or "down below" at a nav station), we recommend using our external GPS antenna.

Fully Water Proof Including USB Connection

The water proof USB connection can be used to connect to the AISWatchMate 850 Transponder during configuration and makes for an easy connection to onboard or home computers if required.

Anchor Watch (Watch this feature in action on YouTube here)

The anchor watch enables you to mark where you dropped anchor and sounds an alarm if your vessel moves outside an adjustable circle. It provides a helpful visual indication of where within your anchor circle the boat is located along with distance and bearing to the anchor point.

Unlike any other product, when used with heading input this one automatically corrects for the location of your GPS antenna. This eliminates cumulative position errors and makes this the most accurate and useful anchor watch there is.

Direct Selective Calling (DSC)

Using the DSC function from your WatchMate allows you to initiate an “individual station call” to vessels that are displayed on your WatchMate screen. This feature makes it easy to message nearby boats, requesting them to switch to a specific channel for a VHF call.

Target Plot

Provides a radar-like display of all vessels within the selected range. The display can be oriented north-up or heading-up so it's very easy and natural to interpret. Dangerous and lost targets are readily identified.

Graphical Plot Shows Crossing Situations

Shows the relative position of a target vs. your vessel at the closest point of approach. This provides a graphical view of the crossing situation and clearly indicates whether a target will pass ahead or behind.


Computes the closest point of approach and time until CPA. Alarms may be based on these and other factors.

Bearing and Range

Computes the bearing and range to each vessel. Bearing can be displayed in magnetic to facilitate easy visual identification using your compass and binoculars. Bearings can alternatively be displayed in true or relative to your vessel's heading.


Vessels and alarms are presented in priority order.

Intelligent Filtering

In crowded operating areas the AISWatchMate 850 Transponder eliminates clutter and false alarms with sophisticated filtering options.

Identify your "fleet"

Targets marked as members of your fleet are displayed with a special icon. Use this to indicate your friends or vessels you commonly work with.

CPA alarm

Triggers alarm if a vessel will come too close. Full control of alarm parameters.

Guard alarm

Sounds alarm if any vessel comes within the specified range. Both CPA alarms and guard alarms may be used together.

External alarm trigger

In addition to the internal alarm, an external buzzer, alarm, or signal light can be interfaced without requiring any additional relays (max 150mA).

Consise and easy to read displays

Uncluttered easy to read display shows all available AIS data.

Safety messages

Displays received AIS Broadcast Safety Messages. These messages may contain important safety, navigation, weather, or shipping information. An AIS mayday safety message can also be sent directly from the AISWatchMate 850 Transponder.

Aids to navigation

Full support for AIS aids to navigation including off-position and virtual aid indicators.

Meteorological and hydrographic display

Displays real-time wind, current, tidal and much more in areas where this information is broadcast.

GPS receiver

Displays built-in GPS satellite status and navigation data such as your position, heading, course and speed.

Large backlit LCD

Adjustable daylight viewable backlit 125mm (5") LCD.

Easy to use

Four buttons control all features. Each button is clearly labeled on-screen. Buttons are backlit for night time use and illumination brightness is controllable. Each setting has on-screen help.

External interface

The AISWatchMate 850 Transponder provides complete AIS and GPS output and is easily interfaced to chart plotters, radars or computers.

Silent Mode

Allows AISWatchMate 850 Transponder to be put in Silent Mode. When in this mode, the AIS receivers and GPS continue to operate normally and all alarms and other features, including the Anchor Watch, are available. The only change is all transmissions are inhibited (except MayDay). Perfect for those times when you want privacy.

VHF "in use" Indicator

Unique VHF “in use” indicator (When used with Vesper Marine’s VHF splitter).

Self Diagnosis

Self diagnosis to provide warnings if AIS, GPS or antenna are not functioning.

Easy installation

Installation is simplified with the AISWatchMate 850 Transponder. No external "black boxes" are required. Simply plug in a VHF antenna and connect the unit to your 12 or 24 volt power source. Depending on where you mount your AISWatchMate 850 Transponder, you may also need our external GPS antenna.

Increased Safety

Your safety is increased when offshore or in busy traffic areas.

Safety at night

When night falls or the weather is bad it is often difficult to see other vessel's lights or determine their direction. The AISWatchMate shows immediately which way the vessel is moving and will even plot the crossing situation.

Positive Identification

You'll have each vessel's name and call sign and others using AIS will also have yours. If you wish to call another vessel you will be able to ensure you are talking to the correct vessel. This is very important when operating in busy areas or in bad weather when visibility is reduced.

Operates on very low power

Energy conscious users know how important low power operation can be particularly on a long voyage when charging from solar or wind. The AISWatchMate consumes far less than a radar, chart plotter or computer. The AISWatchMate takes power saving further by going into a Power Save Mode causing the display and backlight to turn off when no targets are in range, waking up instantly when a target comes into range.

Stand-alone unit doesn't require chart plotter, computer or radar

The AISWatchMate is easy to interface to these devices but none are necessary for its operation. The AISWatchMate 850 Transponder is a fully stand-alone AIS collision warning solution.

Anchor Watch (Watch this feature in action on YouTube here)

The AISWatchMate 850 Transponder includes the Anchor Watch feature, allowing you to mark where you dropped anchor and sounds an alarm if your vessel moves outside a preset circle, indicating that your have begun to drift outside your set radius.

The unique Anchor Watch screen enables you to see the bearing from your vessel to the marked anchor location, the distance between your vessel and the marked anchor location and shows the periodic position of your vessel as dots, indicating how your vessel has moved while anchored.

What's In The Box

  • Protective cover
  • Installation guide
  • Mounting bracket with thumbscrews
  • Flush mounting template
  • 2m (6.5') Power/data cable
  • 1m (3') USB cable
  • Flush mounting seal and screws
Size*208mm wide x 135mm high x 76mm depth (8 3/16” x 5 5/16” x 3”)
LCD panel125mm (5") grayscale sunlight viewable 320x240
LCD light level Off and multiple levels of brightness
EnvironmentalWaterproof (IP67: submersible to 1m for 30 mins)
Operating temperature-25°C to +55°C (-13°F to 131°F)
Power supply10-32 VDC, 3W nominal (Power Save Mode = 210mA @ 12V)
Number of receivers2 AIS (parallel), 1 DSC (timeshared)
Receive sensitivity -113 dBm (<20% PER)
Number of transmitters1 AIS
Transmit power output33 dBm (2 watts)
GPSBuilt-in 50 channel GPS receiver with SBAS (satellite based augmentation systems such as WAAS & EGNOS), selectable smoothing, internal antenna, TNC for optional external antenna
GPS sensitivity-159dBm tracking & navigation
-142dBm acquisition (cold start)
GPS accuracyPosition 2.5m CEP, SBAS 2.0m CEP
External alarm maximum150 mA (power supply voltage)
VHF antenna required50 ohm, 156-162MHz, max 2:1 VSWR, PL-259 connector.
Serial data1 isolated USB port (mini), 1 isolated NMEA input (RS422 4800/38400 baud), 1NMEA output (RS422 4800/38400 baud)
AIS MessagesDisplays all class A and class B position reports, voyage data, static data, aids to navigation, SAR aircraft, SART, MOB, meteorological/hydrographic and safety messages
ProtocolsIEC 61162-1, NMEA 0183, NMEA 0183 HS
StandardsIEC 62287, IEC 60945, IEC 61108, IEC 61162, ITU-R M.1371, ITU-R M.825, ITU-R M.1084
ApprovalsBSH, BABT, CE, US Coast Guard, US FCC, Transport Canada, IC

* Size does not include bracket or cable


Specifications may change due to product improvements and different product release versions.

Includes Vesper Marine's patented AIS technology. For more information about our international patents, contact us.

  AISWatchMate 850 Transponder Icom MA500 TR Simrad A150 Amec Camino 201 Comar CSD 300 *
Customize and filter targets when operating in busy areas Yes No No No No
Computes & prioritizes targets by CPA, TCPA, bearing, range etc Yes No No No No
Ability to connect to computers via waterproof USB Yes No No No No
Super low power consumption Excellent, 3W Poor, 8.4W Poor, <10W Poor, <10W Poor, <13W
Graphically depict crossing situations Yes No No No No
Allows multiple status profiles (Anchor, Harbor, Coastal, Offshore) Yes No No No No
Built in GPS patch antenna Yes No No No No
Personal fleet identification Yes No Yes Yes Unknown
Anchor Watch management and display Yes No No No No
Built-in alarm plus external alarm/buzzer/indicator control Yes Yes No Yes Yes
VHF radio DSC calling Yes Yes No No No
Waterproof, can be externally mounted Yes Limited Yes Limited Yes
Full receive of all Class A and B AIS data and transmission of Class B AIS data Yes Yes Yes Yes Yes
Internal parallel two channel AIS receiver Yes Yes Yes Yes Yes

* Comar CSD-300 requires purchasing and installing an external "black box" AIS transponder such as the CSB-200

Please Note: This information has been gathered from public sources. To the best of Vesper Marine’s knowledge it was correct at the time of publication (early 2012). We want to keep this up-to-date, so if you see anything missing or incorrect, please let us know so we can update this information.