WatchMate 850 Class B Standalone AIS Transponder

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Safety advantages

Sunlight viewable 5" screen

Standalone or Integrate it

Award Winning Performance

Winner of the Practical Sailor Best Choice Award

Other Exclusive Vesper Marine benefits

Low Power Consumption

Keeps it always on, always visible, always watching

Galvanic isolated USB ports

Protect your transponder and connected equipment (laptops) from high current.

Fully Waterproof IPx7

Can be safely mounted anywhere

Upgradable Firmware

Get the latest firmware updates via USB and your computer

Universal Compatibility

Vesper Marine is compatible with all the leading brands of marine equipment and MFDs including Raymarine, Garmin, Furuno, Simrad and many more.

WatchMate 850, a fully standalone transponder with a 5" sunlight viewable screen is easy to use and loaded with features.

Complete Class B AIS Transponder

WatchMate 850 is a Class B AIS transponder with a two channel parallel receiver and transmitter. It transmits your vessel position and details and receives the same kind of information from other vessels with AIS transponders.

The AIS data is sent every few seconds and includes information such as course, speed, latitude, longitude, and heading. Static information about the vessel is sent every few minutes and includes the name, type of vessel, length, beam, draft, etc.

Safety features

WatchMate 850 has powerful safety features that help ensure the safety of your vessel and crew. Its safety features are similar to a smartAIS transponder but it doesn’t have WiFi. The WatchMate 850 provides:

  • Safety Underway. Continuously determine crossing situations, receive collision alarms with full vessel information for critical action.
  • Safety at Anchor. Sleep soundly, knowing you’ll be alerted if your anchor is dragging.
  • Safety for your Crew. Be alerted when your crew activate an AIS MOB device and see their current location for easy retrieval..

It means you can enjoy your time on the water, knowing your WatchMate 850 is always keeping watch in the background and is ready to alert you the moment it detects a hazard or unwanted event.

Safety Underway – Collision Avoidance

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 (CPA) and time until CPA (TCPA). 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 order of priority.

Intelligent Filtering

In crowded operating areas the WatchMate 850 Transponder eliminates clutter by filtering out vessels with no collision risk.

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 an alarm if a vessel will come too close.

Guard alarm

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

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 WatchMate 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.

Safety at Anchor – Anchor Watch

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 you have a heading input our anchor watch automatically corrects for the location of your GPS antenna on-board.This eliminates cumulative position errors and makes the WatchMate 850 the most accurate and useful anchor watch available.

Safety for your Crew - Man Overboard (MOB) alarm

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.

Integrated GPS Antenna

Includes a built-in GPS antenna that provides GPS data to the integrated 50 channel GPS receiver. This internal 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 WatchMate 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.

Direct Selective Calling (DSC)

You can use your WatchMate 850 to initiate an individual DSC call to any vessel displayed on your screen. This feature makes it easy to message nearby boats, requesting them to switch to a specific channel for a VHF call, without having to enter the other vessel’s MMSI number manually into your VHF radio.

The DSC feature works with any VHF radio that accepts the NMEA-0183 DSC sentence.

Sunlight Viewable 5" display

Consise and easy to read

Uncluttered easy to read display shows all available AIS data.

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.

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.

Safety messages

Displays received AIS Broadcast Safety Messages. These messages may contain important safety, navigation, weather, or shipping information.

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.

Easy to install

Plug and Play

No external "black boxes" to mount, power and wire. Just plug in a VHF antenna and connect the WatchMate 850 Transponder to your 12 or 24 volt power supply.

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

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

Ultra-Low power consumption

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

Energy conscious users know how important low power operation can be particularly on a long voyage when charging from solar or wind. The WatchMate 850 consumes far less than a radar, chart plotter or computer. It takes power saving to a new level by going into a Power Save Mode causing the display and backlight to turn off when no targets are in range but waking up instantly when a target comes into range.

External interface

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

Fully Water Proof Including USB Connection

The water proof USB connection can be used to connect the WatchMate 850 to onboard or home computers if required.

Other innovative features

Firmware Updates

When you buy a WatchMate 850, you get not just a product, but an extendable AIS platform. Designed to be compatible with a continuous stream of feature updates, you can update your WatchMate 850 with the latest firmware via USB and your computer

Silent Mode

Allows WatchMate 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 that all transmissions are inhibited. 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.

External alarm trigger

In addition to the internal alarm, an external buzzer, alarm, or signal light can be interfaced withg the WatchMate 850 without requiring any additional relays (max 150mA).

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
Collision Avoidance - Determines crossing situations by CPA and TCPA and triggers alarms with prioritization Yes No prioritization
Anchor Watch - Triggers an alarm if your anchor is dragging Yes No
Safety of Crew - Triggers an alarm if a crew member falls overboard (works with any manufacturer MOB) and provides position information with updates for quick retrieval Yes No
Low power consumption 3W - Very Good 8.4W - Poor
Display 5" sunlight viewable screen Low resolution dot matrix display
View complete vessel details on a single screen Yes NoNeeds multiple (six) screens for vessel details
Direct Selective Calling (DSC) Yes Yes
Built-in GPS antenna with an optional external GPS antenna Yes NoNo internal antenna. Very large external antenna
Intelligent filtering - Filters can be set based on vessel range, speed, CPA and TCPA Yes No
Galvanic isolated USB ports - Protect your transponder and connected equipment (laptops) from high current. Yes No
Fully waterproof IPx7 rating - Can be mounted anywhere Yes Connectors are not waterproof
Bracket or flush mounting included Yes Requires optional flush mount kit

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 (May 2017). 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.