Why a Personal AIS MOB Beacon Matters
A man overboard situation is one of the most time-critical emergencies on the water. Visual contact with a person in the water can be lost within seconds, even in moderate sea conditions, and every moment spent searching rather than recovering puts a life at greater risk. The Ocean Signal rescueME MOB1 addresses this directly by instantly broadcasting the overboard person's GPS-derived position to the vessel's AIS receiver or chart plotter, giving the crew an accurate, real-time target to navigate toward.
Unlike a whistle or a personal strobe alone, the MOB1 provides a precise digital position fix rather than relying on sight or sound. This transforms a frantic search into a directed recovery, which can make a decisive difference in cold or rough water.
How the rescueME MOB1 Works
Once activated, the MOB1 acquires a GPS position fix and begins transmitting AIS messages on the standard AIS frequencies of 161.975 MHz and 162.025 MHz. It sends AIS Message 1 (position report) and Message 14 (MOB status) at a rate of 8 messages per minute, so the chart plotter on your vessel updates your position continuously throughout the recovery.
Activation can happen in two ways. When the MOB1 is correctly installed on an inflatable lifejacket, it activates automatically the moment the lifejacket inflates, with the first transmission beginning within 15 seconds. It can also be activated manually by sliding the red arming tab and removing the grey activation slide. A built-in strobe light begins flashing immediately upon activation to provide a visible signal in low-light or night-time conditions.
The indicator LED provides real-time feedback on GPS status: red flashes indicate the unit is acquiring a position fix, while green flashes confirm that a GPS position is being received and transmitted. Eight short flashes indicate an AIS transmission burst is in progress.
AIS Range and Compatibility
Depending on conditions, the MOB1 can communicate with AIS-equipped vessels within approximately a 5-mile radius. Most modern AIS receivers comply with the standards required to receive MOB transmissions. If you are using older AIS equipment, Ocean Signal recommends checking compatibility directly with your equipment manufacturer before relying on the MOB1 as part of your safety plan.
In Canada, the MOB1 is approved for AIS operation only under Industry Canada RSS287. The unit also incorporates a DSC (Digital Selective Calling) function; however, DSC functionality is subject to the regulations of each country and is not permitted for use in Canada under current approvals.
Lifejacket Installation and MMSI Programming
The MOB1 is compatible with most inflatable lifejackets and attaches via a mounting bracket and activation tape that connects to the lifejacket bladder. When the bladder inflates, it pulls the activation slide free, triggering the device automatically. Full installation instructions are available in the MOB1 PFD Installation Instructions document, with a separate instruction sheet available for lifejackets with welded-in bladders.
If your vessel's VHF radio is DSC-enabled, it is strongly recommended to programme your vessel's MMSI number into the MOB1 using the free PC-based or web-based programming application available from Ocean Signal. This allows the MOB1 to send distress information directly to your vessel's DSC radio. Note that DSC functionality and MMSI programming apply only in countries where DSC operation is permitted.
After installation, the MOB1 should be armed by sliding the red arming tab to the armed position. Failure to arm the device will prevent automatic activation and may also interfere with correct lifejacket inflation.
Testing and Maintenance
Ocean Signal recommends a monthly functional test to confirm the MOB1 is operating correctly. The test is initiated by pressing and holding the TEST/OFF key for one second. After a brief pause, the strobe flashes and the indicator LED displays a pass or fail result along with a battery status indication based on the number of LED flashes.
An AIS transmission and GPS test can also be performed, though this should be limited to a maximum of three times per year to preserve battery life. After a successful AIS test, the message 'MOB1 TEST' will appear on a compatible AIS receiver or chart plotter display. Each test consumes a small amount of battery capacity, so the battery should be replaced if the indicator shows amber (more than one hour of use) or if the unit has been activated in a real emergency.
Battery replacement must be carried out at an Ocean Signal authorised battery replacement centre. The MOB1 is not user-serviceable, and opening the case will void the warranty.
Physical Design and Environmental Ratings
The rescueME MOB1 lives up to its claim as the world's smallest personal AIS MOB device. At 134 mm x 38 mm x 27 mm and weighing just 92 grams, it is compact enough to be carried on a lifejacket without adding meaningful bulk or weight. The low-profile design makes it practical for everyday wear on offshore passages or racing.
The unit is built to withstand demanding marine environments. It is rated for water immersion at 2 bar for more than 60 minutes, designed to meet a drop test into water from 20 metres, and tested for drops onto hard surfaces from 1 metre across 6 sides. The operational temperature range spans -20°C to +55°C, making it suitable for use in cold northern waters as well as warmer climates.
Specifications
- AIS Transmit Power (EIRP): 1 Watt
- AIS Frequency: 161.975 / 162.025 MHz ±500 Hz
- AIS Baud Rate: 9600 baud
- AIS Synchronisation: UTC
- AIS Messages: Message 1 (Position), Message 14 (MOB status)
- AIS Repetition Interval: 8 messages per minute; Message 14 sent twice every 4 minutes
- DSC Transmit Power (EIRP): 0.5 Watt
- DSC Frequency: 156.525 MHz
- DSC Baud Rate: 1200 baud
- DSC Message Repetition: Once every 5 minutes (Relay only)
- First Alert Transmission: Within 15 seconds of activation
- Operational Temperature Range: -20°C to +55°C
- Storage Temperature Range: -30°C to +70°C
- Humidity (Damp Heat): 40°C at 93% relative humidity
- Drop Test (Hard Surface): 1 m, 6 sides
- Drop Test (Water): Designed to meet 20 m, 3 sides
- Water Immersion: 2 bar for more than 60 minutes
- Thermal Shock: 45° into 100 mm of water for more than 1 hour
- Weight: 92 grams
- Dimensions: 134 mm x 38 mm x 27 mm (59 mm over bracket)
- Battery Type: LiMnO2 (two Energizer 123 cells in series)
- Battery Nominal Voltage: 6V
- Battery Weight: 34 grams
- Canadian Approval: Industry Canada RSS287 (AIS only)
- USA Approval: CFR47 Part 95K
- Warranty: 5 years from date of purchase
Key Features
- Automatic activation on lifejacket inflation: the MOB1 triggers within 15 seconds of the lifejacket inflating, requiring no manual intervention from the person in the water
- Built-in GPS position reporting: transmits your precise location to your vessel's AIS receiver or chart plotter, turning a search into a directed recovery
- Continuous AIS position updates: broadcasts 8 AIS messages per minute so your crew can track your position in real time throughout the recovery
- Up to 5-mile AIS range: depending on conditions, alerts not only your own vessel but also other AIS-equipped boats in the vicinity
- Integrated strobe light: flashes immediately upon activation to provide a visible signal in darkness or low-light conditions
- World's smallest personal AIS MOB device: compact and lightweight enough to be worn on a lifejacket without adding significant bulk
- Rated for deep water immersion: withstands 2 bar pressure for more than 60 minutes, providing reliable operation even if submerged
- Wide operational temperature range: performs from -20°C to +55°C, suitable for cold-water sailing conditions
- Compatible with most inflatable lifejackets: straightforward installation using the included mounting bracket and activation tape
- Monthly self-test function: allows routine verification of device readiness and battery status without requiring specialist equipment
- 5-year limited warranty: long-term coverage against manufacturing defects provides confidence in the investment
 Ocean Signal MOB1 User Manual
MOB1 PFD Installation Instructions
Ocean Signal MOB1 Safety Data Sheet
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