At first glance, the Man Over Board (MOB) functionality of Cortex might appear to be just another MOB waypoint feature found on most modern multi-function displays (MFDs), but there’s actually much more to it. We believe MOB is important enough to deserve its own dedicated alarm system. One that provides an immediate alarm, a simple but powerful display that aids the crew in fast MOB retrieval without being a distraction from the task at hand, while also integrating with other systems on board.
Not all MOB systems are created equal
MFDs typically have a MOB button, some less obvious and intuitive than others. The example here requires both tick and cross buttons to be held down at the same time! Not exactly user-friendly for anyone who hasn’t read the instruction manual. Some also prevent an immediate MOB waypoint drop by first asking the user if this is really what they want to do (not always what you need in an emergency situation). MOB backtrack modes do exist, but many assume the operator already knows how to use their waypoint functionality. MFDs also rely on being connected to an external AIS transponder over NMEA 2000 to be able to receive incoming AIS MOB messages.
When an AIS MOB device is activated it immediately sends out an AIS safety message. This will normally be received before a position message since it takes the AIS MOB some time to acquire a GPS fix. MFDs will typically alert that a safety message has been received but often with no context that it’s from an MOB device. When the position message is received, some modern MFDs still choose to display the AIS MOB target as a Class B vessel, instead of the easily identifiable red cross with a circle.
AIS MOB safety messages are sometimes displayed by MFDs but with no context.
We are not alone in thinking that MOB functionality should not be entirely relegated to the vessel’s chart plotter. There are some dedicated MOB button alarm systems that spoof AIS MOB message reception by sending a fake AIS MOB position report to the NMEA 2000 network. Although you have to admire the ingenuity of this approach, you have to wonder why this is necessary for the modern age when there is a dedicated NMEA 2000 PGN for MOB alarms and what confusion may result, especially when using it alongside an MFD that displays an AIS vessel instead of an AIS MOB.
Some MFDs still display a received AIS MOB position as a Class B vessel.
A new approach to MOB
Cortex dedicated MOB situation screen
Cortex aims to create a simple yet effective MOB alarm system that is easy for the whole crew to use and understand without prior training. The MOB button is dedicated solely to MOB mode, is labeled with human-readable text rather than an ambiguous icon, and is backlit so can be easily seen in all ambient lighting conditions. When pressed Cortex will immediately:
- Sound an alarm using a human voice so everyone on board knows immediately what is happening.
- Drop a waypoint using the current GPS position.
- Broadcast the MOB event on the NMEA 2000 network using the MOB PGN 127233. This may also automatically trigger a MOB retrieval mode on some MFDs.
- Display a dedicated situation screen for MOB retrieval. Range and bearing to the MOB are displayed, along with a suggested course to navigate back to them quickly. The water temperature and time since the MOB button was pressed are also available. The display is simple and clear with no unnecessary clutter, focusing solely on retrieval of the MOB.
- Cortex is also an AIS transponder, so as soon as an AIS MOB position message is received, the trackback changes to track the AIS MOB target instead of using a different icon, but leaves the originally dropped waypoint there for reference. It also sends AIS MOB position messages to the NMEA 2000 network.
- Since Cortex is also a powerful VHF and DSC communication device, without having to navigate away from the MOB retrieval screen or go to another device, a VHF and DSC distress call can also be initiated.