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HAVE YOU SEEN OPEN WATER? It's a chilling film about two scuba-divers lost at sea after becoming separated from their dive-boat, designed to get divers' hearts racing as they witness the events leading up to the realisation of one of our worst nightmares.
It’s loosely based on the true story of Tom and Eileen Lonergan, who in 1998 went diving on Australia's Great Barrier Reef, and were accidentally left behind by the dive-boat when the crew failed to do an accurate headcount.
This type of incident isn't common, but it's not that unusual either. A quick Internet search reveals an alarming number of tales of divers adrift in big oceans, and I'm sure many other incidents are never reported.

Last July, experienced diver Jacob Childs sparked a massive search and rescue operation after disappearing from a group dive off his local Queensland coast. He later said that he got lost after surfacing in strong currents and drifting away from the boat.
The 30-year-old recorded dramatic footage of the ordeal on his GoPro. He feared the worst as the sun began to set, and filmed what he thought would be his final moments.
In the video he said: “So, that’s it. The sun goes down, they won’t do nothing. That’s a wrap on old Jakey.” Luckily, after six hours adrift and in darkness, the crew of a search aircraft located him. He had drifted some eight miles.
Also last year, British divers Jeff and Julie Byrne were with a group that became lost after surfacing off Mauritius to find that their dive-boat had disappeared.
Along with three other divers, including a divemaster, they were swept 12 miles by strong currents. The SAR operation involved 22 boats, two helicopters and a spotter-plane.
The divers were found seven hours later by a pleasure boat and recovered, dehydrated and sunburnt. Mrs Byrne was later diagnosed with Post Traumatic Stress Disorder.
“Panic immediately set in and some of the group’s younger members freaked out,” she said. The five divers had linked arms and inflated their BCs to stay afloat and together.
“We thought we were done for,” she went on. “When you’re in seas where sharks are common, your mind plays tricks on you. Each time a fish, leaf or piece of seaweed brushed my ankle my heart would stop.
“We saw helicopters flying overhead, we yelled and screamed, but they couldn’t see us.”
It might be argued that such incidents could have been avoided by following safety guidelines and employing lo-tec location aids such as DSMBs, whistles and air-horns or dive-lights.
However, divers are mainly lost at sea when changeable weather, unpredictable currents and, most importantly, human error combine to reduce the effectiveness of such locators.
It’s in these rare but life-threatening situations that hi-tec systems could be the only way out of serious trouble.

Location Devices
All the electronic emergency location systems on the market require a sender and receiver. Some have their own vessel-mounted base-stations directly linked to dedicated transmitters, and some deliver a distress signal to receiving satellites (SARSAT) orbiting Earth, alerting global SAR operators to the victim’s location via GPS.
These emergency position-indicating radio beacons (EPIRBs) are used widely in the marine environment, and are registered primarily to individual vessels.
An alternative is a personal locator beacon (PLB), a smaller unit with the same features as an EPIRB, sending a coded message on the 406MHz distress frequency monitored by the COSPAS-SARSAT satellite system, but registered to an individual. PLBs are generally rated as waterproof to a maximum of 3m, so have to be kept in a dedicated depth-rated container.
One of the most popular locator devices designed for the dive world has been a distress-signal unit with an integrated marine VHF radio. This allows direct contact to the dive-vessel’s onboard radio or further afield using the universal emergency channel 16 frequency, and also providing GPS co-ordinates.
There’s much to be said for this type of VHF radio safety instrument, but because of countries’ differing laws regarding licensing for the operators of marine VHF radios, divers without the necessary certification are often not allowed to use them – and this applies in the UK.
The company that produced the original marine VHF radio device has since released
a new diver-locator system, one that doesn’t involve dedicated base units, registration, licensing, subscription or certification.

The Design
The Nautilus Marine Rescue GPS has been designed to send its GPS position, accurate to 1.5m, and a “Man Overboard” distress message to all ships equipped with an AIS (Automatic Identification System) VHF marine radio within a 34-mile radius. The Individual Distress Alert message is transmitted on an AIS frequency between 161.975 and 162.025 MHz.
The unit can also be used for Digital Selective Calling (DSC). This requires a DSC-compliant marine radio (generally identified by a distinctive red button marked “Distress”).
DSC technology facilitates direct vessel-to-vessel communication as part of the Global Marine Distress Safety System (GMDSS) and allows digital messaging directly to your chosen (and pre-programmed) VHF marine radio via channel 70 on a frequency of 156.525 Mhz, negating the use of the universal emergency channel 16.
The Nautilus Marine Rescue GPS is housed in a plastic watertight case with a flip-open dive-cap giving access to a three-button interface and sprung stainless-steel antenna. Silicon O-ring seals provide a depth-rating of 130m.
Two user-changeable CR123 lithium-ion batteries power the unit, which measures 75 x 97 x 39mm, weighs 131g including batteries and is positively buoyant.
The GPS unit is supplied with an antenna rewind tool, and optional neoprene or silicon storage pouches are available, as is a small double-ended coiled lanyard.

In Use
I took the Nautilus Marine Rescue GPS for some real-world testing while diving from Petit St Vincent in the Caribbean waters of the Grenadines.
“Real-world” meant that I had to contend with the dive-centre’s customised dive-boat being sent away to dry dock for an engine re-fit the day before I arrived. The fishing-boat hired as a temporary replacement had no DSC-enabled radio fitted.
This meant that I was unable to test the effectiveness of the system without transmitting a general distress signal that would be received by nearby merchant vessels, and no doubt having to appease furious skippers and other dive-boat users responding to what they assumed to be a genuine cry for help.
Instead, I took the opportunity to capture a few images of the unit, deployed and ready to go.
Undaunted and back on home turf, I sought the help of ex-colleagues from the Fire Service’s Swift Water Rescue team.
These specialists use AIS- and DSC-enabled marine VHF radios on their rescue craft while plying their trade on the country’s inland waterways.
With their help I would be able to conduct a reasonably meaningful test of the Nautilus well away from the coast, and without involving thousands of marine boat-users.
We met at a huge reservoir on the outskirts of London where the firefighters conduct their training. The first thing I wanted to try was the DSC functionality.
I needed to configure the Marine Rescue GPS unit with the boat’s VHF radio by programming the boat’s Maritime Mobile Service Identity (MMSI) nine-digit code into the Nautilus.
This was a straightforward task using the Nautilus Lifeline programming app, downloaded onto my iPhone and delivered via a series of flashes from the phone’s built-in camera strobe light to the Marine Rescue GPS device.
Next thing to do was to put the Nautilus through its test sequence to show that it had actually acquired its GPS position and the batteries were charged.
These simple set-up procedures completed, the boys dropped me off on the bank of the reservoir and sped off to the far side on the boat.
A five-second press of the yellow button and they reported almost immediately via handheld radio that a signal had been received on their marine radio displayed as text, giving the unit’s pre-programmed MID number and its GPS co-ordinates and enabling them to locate me quickly.
The next thing to do was release the sprung-steel antenna and go for a full-on “Distress” transmission. A five-second press of the red “Help” button was all that was needed.
The Nautilus went through a sequence of flashing red lights until it had acquired a GPS lock, then the light went solid as it transmitted the AIS signal.
This was followed by a steadily blinking white strobe light to help in locating the signal source visually.
The fire-crew acknowledged receipt of the distress call, and again sped to my location. A five-second push of the red Help button deactivated the transmission.
At this stage I have to tell you that the Swift Water Rescue technicians had sent a number of voice messages to alert other AIS users in the vicinity to inform them that we were conducting tests, and to ignore the short-lived distress call.
I’ll sum up with a little disclaimer. The tests, although conclusive, were carried out in benign conditions.
I can’t report on the unit’s performance in rough seas over vast distances because I didn’t have the opportunity nor logistics to try it without risking a battering from irate boat-users.

This robust little box of tricks is simplicity personified to operate – un-latch the lid, flip it open and switch it on, release the antenna and press the red button for five seconds and that’s it. Your distress signal will be instantly transmitted to all shipping in the vicinity equipped with AIS Marine VHF radios.
The Nautilus GPS needs no maintenance other than a post-dive rinse and a periodic O-ring and battery check. The batteries have a shelf-life of up to five years, so you could conceivably attach it to a BC waist-belt and forget all about it until – well, you know.
There are a couple of niggles to tell you about. Firstly, to deploy the antenna and give access to the red Help button, a clear plastic cover needs to be slid off the unit’s head and, you guessed it, it’s easy to lose. I spent 20 minutes scratching about in the muddy waters at the reservoir looking for it after the tests.
The second thing is the rewinding of the antenna. A winding tool is supplied but it’s not intuitive to use and, with no instructions, I struggled.
All said, however, if you actually needed to use this device in an emergency, the last thing on your mind would be the loss of the cover or winding the antenna back in.
The DSC function is a nice touch, but not essential to a successful outcome. However, by making the effort to pair the Nautilus to your dive-boat’s DSC-enabled radio you’ll be able to alert it to your position long before the situation spirals out of control. Should that happen and your circumstances become critical, you can always fall back on the red button.
Cleverly, the Nautilus Marine Rescue GPS uses existing radio technology found on all but a few seagoing vessels to notify them of an emergency without the need for registration or certification, making this unit truly universal and suitable for the masses.
All the diver needs, to be confident that any future separation drama is unlikely to escalate into a crisis, is to invest in the standalone GPS unit, a pair of batteries and a protective case.
“You don’t think you need one – until you do,” says Mike Lever, CEO of Nautilus: I’m sure that resonates with Jacob Childs, Jeff and Julie Byrne and all the other divers who have had the misfortune to be lost at sea. I’ve been there too, and it does with me.
The Nautilus Marine Rescue GPS is exactly what I’ve been waiting for, and may well have set a new benchmark for diver safety.
A word of caution, however: as good as I think this product is, it should be used in conjunction with, and never as a substitute for, a large, brightly coloured DSMB.
Nor should it be relied on in really remote destinations where there are unlikely to be other marine craft to hear your cry for help – that is the domain of hi-tec PLBs with satellite links.

PRICES: Lifeline GPS unit, £195. Silicon pouch, £20. Neoprene pouch, £34. Coiled lanyard, £7
APP: Nautilus Lifeline App free from Apple iTunes store or Google Play for Android devices
AIS FREQUENCY: 161.975 & 162.025 MHz
AIS RANGE: Up to 34 miles (dependent on sea state)
POWERED BY: 2 x CR123 li-ion cells
SIZE & WEIGHT: 75 x 97 x 39mm. 131g with batteries

Appeared in DIVER March 2017


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