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October 2008    Download the Entire Issue (PDF) Available to the Public Vol. 23, No. 10   RSS Feed for Undercurrent Issues
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How Divers Will Never Be Lost Again

new personal GPS device still working out the kinks

from the October, 2008 issue of Undercurrent   Subscribe Now

Arent you going to fasten your seatbelt? I asked my Indonesian driver. Why should I? he retorted. Im not going to have an accident. That sums up all safety equipment. If regulations didnt force us to have them, wed happily do without.

The German manufacturers of the Electronic Rescue and Locating System (ENOS for short) would like to see every dive boat equipped with their equipment. But as they improve their technology, theyre struggling to persuade dive operations to spend the money. With boat owners smarting over the high cost of marine fuel, they are hardly likely to want to splash out. Besides, theyre not going to lose anyone, are they?

Hold That Transmitter, High, Lost Diver

Hold That Transmitter
High, Lost Diver

Would you pay a surcharge to book a boat that had a search unit and sufficient transmitters to equip every diver on board? After all, with the charge for the boat unit running about $4,500 and each diver unit costing $1,250, that sort of investment doesnt come easy. However, Seareq, the German manufacturer of ENOS, told us that American dive centers have not used ENOS because of rather complicated international radio frequency laws and rules worldwide, which were cleared up for the American market in the last 12 months. Until now, it was not possible for boat operators in U.S. territories to purchase the ENOS system.

It seems the equipment must be supplied for use in a specific territory. I took a set to Egypt and tried it out during my voyage on the Miss Nouran liveaboard in the Red Sea. The ENOS System869 operates with a radio frequency that is license-free so its use doesnt have to be reported to the authorities in that country. The system works in conjunction with GPS, which is operated by the U.S. government. It works independently of any international rescue service and as such has no operational charges attributed to it.

Each diver carries a transmitter that is only activated at the surface during an emergency. The boat carries a receiver unit that must be switched on while divers are in the water. When a diver activates the transmitter, the receiver emits a loud sound, transmits the lost divers GPS position, then calculates the distance and direction of the emergency signal. Its independent power supply means it can be used in a small boat such as a rigid-hull inflatable (RIB). Like VHF radio, it works by line-ofsight and has a range of around two miles in a small boat. By positioning a separate antenna high up on the main vessel, it is claimed that the ENOS systems range can be extended to six miles or more.

The lost diver at the surface simply switches on the unit he has been carrying in his BC pocket or clipped to it by its lanyard. He holds it as high as he can while it triangulates on three satellites and sends the emergency signal and position to the receiver unit back on the boat. Provided the captain remembers to steer around obstructions such as reefs, he can head directly to where the lost diver is positioned. If a group of divers have an incident which results in them coming up all over the place and sending emergency transmissions, the receiver unit can log them all.

On the Miss Nouran, the receiver unit was connected to a VHF aerial rigged high on the boats cross-trees to give it as much range as possible. For smaller boats, you can use a small aerial attached to the unit in its watertight case or rig it to its Aframe. The GPS aerial only needs to see the sky.

The first problem I encountered was that Miss Nourans RIB drivers were too efficient at picking up surfacing divers. The safety beacons were held up above the water and the receiver unit squawked that there was a diver who needed rescuing, but that person was always out of the water before a unit had time to triangulate on the three GPS satellites. That meant they transmitted no actual position before the unit was switched off.

So I sent someone out in a RIB. It took four minutes for the divers transmitter to lock on to the required number of satellites and for the boats receiver to get the bearing and distance. Because the information needs to be transmitted back to the boat by radio, the range of the unit is limited by the curvature of the earth. The higher the receiving aerial is positioned, the farther it can see. Also, the divers unit is slightly buoyant so that in a worst-case scenario it can still bob in the water and do its job.

Alas, its never that simple. Like anything that uses sophisticated electronics, there are inevitably development problems. Peter Witmer of the Galapagos Aggressor I and II fleet reports a trying time with diver units breaking and vessel-generated electricity causing spikes in the voltage that damaged the receiver unit. The latest model has a battery charged in the same way as a laptop, so that should give protection from spikes. Witmer tells Undercurrent that the diver units have been redesigned and are now good but the effective range is disappointing. Because it works by line-of-sight, the VHF aerial needs to have an unobscured view of the ocean and be mounted as high as possible. But Witmer admits there are so many electronics mounted on both vessels (location systems, two radars, sat phones, cell-phone TV and two radio systems), the tops looks like Christmas trees. This might be causing interference.

So far we had two incidents and the system worked real time, Witmer says. Nothing serious, fortunately. However, the Aggressors experience with ENOS has been expensive and spotty. He reports good product support from Germany, and ENOS reps will go to the Galapagos soon to review the problems. Still, he doesnt yet feel that the system is fully reliable.

Regardless, I, for one, would feel more confident booking a dive boat that used it. Besides the Galapagos Aggressor I and II, three boats currently use ENOS, including MY Seven Seas in the Red Sea, MV Carina in the Maldives and S/C King Bambo in the Seychelles. Dive groups traveling to Egypt can rent the equipment equipment and take it on board with them, but they must be sure someone is always with the receiver unit while they are in the water and that its someone who knows how to use it. Renting a set with six transmitters and one receiver for a week costs around $120 per person.

John Bantin is the technical editor of DIVER magazine in the United Kingdom. For 20 years, he has used and received virtually every piece of equipment available in the UK and the U.S., and makes around 300 dives per year for that purpose. He is also a professional underwater photographer.

P.S. from Ben Davison: Undercurrent subscriber Sean Bruner (Tucson, AZ) was on the Galapagos Aggressor in August and said, They provided each diver with a GPS locator device in case you surface far from the boat. My wife tried to open hers the first day at Wolf Island but it was stuck shut. The next day at Darwin, they were still stuck shut and when the five divers chasing the whale shark surfaced, they were so far from the boat that they tried to activate the GPS. They were all stuck shut. Finally, one was opened and after waiting 20 minutes (with five silkies circling underneath), they were able to signal the boat and were picked up. The crew got them to open easily the next day.

So a word to all divers: As with any piece of equipment, ensure its operational before diving with it. And a thanks goes to the Aggressor fleet for investing in such important technology and helping to improve it. We divers need a foolproof rescue device.

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