Real-Time Rescue – A personal GNSS tracker
Peter Hall and Christin Edwards
It is recognised that if a person falls into cold water, their survival time is very short. There is a concentrated focus on safety issues in the maritime world, as demonstrated by the introduction of the Global Maritime Distress Safety System (GMDSS). This is an internationally agreed set of safety procedures, types of equipment, and communications protocols used to increase safety and aid rescue.
This person-over-board project (POB) aims to exploit a recognised gap in the commercial and marine leisure markets, by combining a crew overboard alarm and a real-time tracking and retrieval system. There are two components to this project, the device worn by the crew and the fixed ship unit.
The crew unit is a small electronics device worn by each crewmember, either built in to a lifejacket or with its own float and tether system. The ship unit is seen as add-on electronics mounted permanently on board the boat, compatible and interfacing with existing electronic equipment.
Most modern vessels have a GNSS receiver or plotter, a cockpit-mounted GNSS repeater, and a VHF radio. The object of this project is to extend the use of this existing technology without compromising its familiar functionality. The shipboard unit will serve as the medium between the existing on-board GPS receiver and the cockpit repeater.
If a crewmember falls overboard, immersion in water activates the personal crew device (POB); the ship unit logs the position and initiates an audio and visual alarm. The crew unit then obtains a GNSS fix, using aided start-up from the ship if necessary, and transmits its position at regular intervals. The ship unit starts tracking the POB position and generating instructions for recovery in the form of a heading and distance to the casualty. Should the parent vessel go out of range, the ship unit can detect the loss of POB signal and switch to calculating the expected position using dead reckoning from its previously logged positions. This system is also capable of dealing with multiple casualties in the water.
The future evolution of this unit:
- The ship unit can also function as a position monitor, raising an alarm if a vessel moves unexpectedly.
- The ship unit can feed an alarm directly into the existing emergency GMDSS system.
- As the crew and ship units are based on the same hardware, the unit can evolve into a portable tracking unit with a wide range of applications.
- The fixed and portable units can work towards implementing the features of the SAR/Galileo system as they become available.
Some current devices raise an alarm on the international distress frequency, others employ expensive direction finders that home onto a beacon. Our system is unique in that it constantly signals the casualty’s position back to the vessel and guides the crew to the actual real-time position, thus enabling an effective rescue. The use of intelligent communications by implementing an ACK/NAK protocol ensures that the signals get through.
Lack of familiarity with boat safety equipment is a major problem. With our system, in an emergency the crew can use familiar equipment mounted in the correct place, displaying familiar data that is to be used for the rescue. There is nothing new to learn, and therefore no time-consuming hesitation or uncertainty. This is a significant safety improvement for trained professionals and leisure sailors alike.
This is achieved by interfacing with the vessel’s navigational system and feeding in signals that enable it to display the distance and heading to the actual casualty. This is shown in conjunction with the current heading and speed. The display can be numeric or graphic, but the result is always instant information in a known form right when it is needed.
Rescue services (RNLI)
Ocean and offshore yacht racing
Safety cover of dinghy racing
Leisure marine activities, such as sailing and motorboating
Youth activities, such as canoeing
-> Anyone who ventures into a maritime environment
- A major problem in the marine environment is that much of the safety equipment is very rarely used; in an emergency the crew is expected to use unfamiliar objects. The Sci-Tech POB system utilises familiar equipment in a simple but novel way.
- In a fleet of vessels equipped with the system, every vessel monitors the casualty and can be in a position to perform the rescue.
- Protection of life at an affordable price
- Easily portable between vessels
- In a corporate environment, it could become mandatory health and safety equipment or be requested by insurance companies.
- It may be seen as a necessary safety device in cases where risk assessment might otherwise preclude the activity or task.
Sci-Tech Systems Ltd.
Unit 11, Mildmay House, Foundry Lane
Burnham-on-Crouch, Essex, CM0 8BL
phone: +44 (0)1621 857386
fax: 44 (0)870 7050959