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Sea Change Technology’s Shark Shield: how one Australian company could make your visits to the beach a little safer . . . Shark! by Ross Tester 16  Silicon Chip www.siliconchip.com.au T he very mention of the word “shark” engenders dread in the vast majority of humans. After all, we’ve all seen Jaws, Jaws 2, Jaws 3 (how many is it now?) and we know what those nasty creatures can do. And how clever they are. And every year, just about the time you are starting to think that it’s safe to go back in the water, one or more of our more sensationalist papers trots out some expert or other to warn that “this year will be one of the most dangerous on record for shark attacks . . .” Yet most of our fear of sharks is completely without foundation. As regular readers of SILICON CHIP may know, on my days off for good behaviour I am involved in Surf Lifesaving on Sydney’s Northern Beaches. This includes training and examining new recruits. One of the first and most-raised topics is about sharks. It’s not just the kids – all ages are petrified! When they see images on TV of the recent 2002 National Surf Lifesaving Championships at Kurrawa (on Queensland’s Gold Coast) with literally dozens of sharks close inshore in a feeding frenzy, that fear is perhaps understandable. To try to reassure them, I ask all new squad members to tell me when the last fatal shark attack occurred around Sydney. The answers usually vary anywhere from “last year” to “about 10 years ago.” The truth is that the last fatal attack occurred not off a surfing beach but in Middle Harbour almost 40 years ago (1963 to be precise), when actress Marcia Hathaway was mauled by a shark in less than two feet of water. (She died from shock/blood loss when the ambulance sent to retrieve her burned between May and November. In fact, you’re much more likely to be killed by a wayward bee on your way to the beach than you are being taken by a shark. Worldwide, there are perhaps 50-75 shark attacks per year, with an average of 8-12 fatalities. Allergic reaction to bee stings takes many, many times this number each year! There were 76 documented attacks in 2001, 5 of them fatal. This compares with 85 reported attacks in 2000, (12 of them fatal) and 58 attacks in 1999. Remember, this is world-wide! And compare that tiny number of fatalities with the 100-200 million sharks caught each year through fishing – they might be excused for wanting to get even! Of course, there have been attacks – some of them fatal – in other areas of Australia. Two attacks in quick succession on Perth’s Cottesloe Beach a couple of years back certainly got the tabloids into a feeding frenzy! Shark netting its clutch out trying to get back up the steep track from the beach). And as far as attacks off an ocean beach are concerned, we go back even further – much further. The last occurred in 1937 – incidentally the same year in which shark netting was introduced in Sydney. And there have never been any reported attacks We mentioned shark netting a moment ago. This has been the preferred method of protecting humans for more than half a century. The idea of the nets (which are generally only 200m long and 6m deep) is not so much to “catch” sharks – though they do that – but to discourage sharks from establishing their “territory” near a Fitting the Sea Change Technology “Shark Shield” before snorkelling or even catching waves – it’s as simple as strapping the unit to your leg, and it could save your life . . . www.siliconchip.com.au May 2002  17 The “figure 8” field produced around a diver, using the scuba tank as one of the electrodes. A board rider has two trailing electrodes, resulting in a polar pattern under the surfboard. The field for a swimmer or snorkeller with one trailing electrode is similar to that from the board rider. beach. The nets, with 50cm mesh, are not permanent – they are moved from beach to beach by contractors. That they are successful is not questioned (no attacks off any Sydney beach since installation). However, in recent years conservationists have started to question the number of other marine creatures accidentally caught by the nets (dolphins, turtles, etc). Fortunately for swimmers, governments have decided to keep the nets in place. Witness the history of Durban (South Africa) where a mesh barrier was put into place as far back as 1907. It was in place for 21 years before it was allowed to fall apart. During those 21 years there was never an attack off Durban. Records for the years between 1943 and 1951 show that Durban had 21 shark attacks. very commonly found in Sydney and southern Australia – might lick you to death (or perhaps scare you to death!). There are three sharks which dominate reports of attacks: the great white, the tiger and the bull shark. All three can grow to very large sizes and all three are common in Australia. There are areas along Australia’s southern coast where large numbers of Great Whites congregate; needless to say, swimming and surfing are not high on the sporting agenda. . . Having said that, the majority of attacks occur in the warmer waters of the tropics. the shark can detect their presence, via the Ampullae of Lorenzini, even under the sand. Not all sharks are dangerous There are around 350 shark species, of which 32 have been proved to attack humans. Another 35 or so are considered potentially dangerous. The rest – such as the Port Jackson shark 18  Silicon Chip Why do sharks attack? Many experts believe that attacks (particularly those NOT of the “big three”) are often a case of mistaken identity – to a shark, a swimmer or surfer in a wet suit does not look all that different to a seal (yum!). There have been many cases of sharks “tasting and spitting” which tends to reinforce that theory. Some sharks, though, have been known to stalk victims. Others stage “hit and run” attacks where the victim has no idea of the shark’s presence until the last moment. It is believed that sharks sense their prey at least partially by electrical means. On the nose of all predatory sharks are small sensory organs called the “Ampullae of Lorenzini”. These organs can detect the tiniest of electrical currents (which are generated by all animals, humans included) and can guide a shark to its prey from some distance away, even to completely hidden prey. You might have seen film of sharks “digging” out stingrays which had buried themselves under a layer of sand to try to escape: Turning the tables It is those same Ampullae of Lorenzini that researchers in South Africa discovered, several years ago, could be used to repel sharks. By setting up an electric field around a swimmer/diver/surfer/etc, any predatory shark entering the field finds it impossible to stay. The same field does not affect humans or other marine creatures because they do not have the sensory organs. The exact mechanism – why it works – is not yet completely understood. But it could be that the generated electric field is not only detected by the Ampullae of Lorenzini – it massively overloads this ultra-sensitive organ. The result is extreme discomfort and muscular spasms in the shark which cause it to veer away whenever it enters the field. There is also evidence that the shark loses muscle control around the mouth and gill, meaning it may not be able to take a bite even if it wanted to. But noone is quite willing to test that theory! First developed in Natal, South Africa, for professional divers, Adelaide-based SeaChange Technology has refined and miniaturised the original “Shark Pod” into its recently released “Shark Shield.”. Both use the same technology but the Shark Shield is very much smaller and lighter, a “personal” version. SeaChange Technology’s Technical Director, Mike Wescombe-Down, said that the Shark Shield was the result of many years of development, refinement and above all testing and retesting. And those tests have been 100% effective agains a variety of sharks. He was not at all reticent about www.siliconchip.com.au sharing some of the technical features of the Shark Shield with SILICON CHIP. However, we must warn readers not to think this information is an invitation to try to build your own version. As we mentioned before, sharks can sense the tiniest electrical stimulii – and during their early testing, the Natal Board of Sharks even found that a very slight variation in the waveform actually attracted sharks! We’d hate to think that readers would try to build their own version, because if it doesn’t work as intended, you won’t get a second chance to fix it! “You can’t argue with a Great White bearing down on you at speed,” said Mike. How does it work? The heart of the Shark Shield is an intelligent microprocessor-controlled high-voltage pulse generator. The patented, very complex waveform includes a very fast-rising pulse every 500ms. This is fed into the trailing electrodes or “antennas” which in turn produce the electric field in the water. The microprocessor not only controls the waveform generation but also detects whether the antennas are under water (it throttles back the output if they are not) or whether they have become short circuited. If so, it switches over to a test mode and restores the output when the short is removed. The pulsing field (which can be felt on bare skin in salt water but does not cause discomfort at reasonable distance) decays quite dramatically from the antennas but is effective up to a range of about 2-3 metres and even up to five metres. Several factors affect the output and hence distance: Water temperature (the warmer the water the more output) – fortunate, because shark attacks do increase with warmer water! Battery life – also affected by temperature. Water salinity – requires salt water (does not work in fresh, is very limited in brackish). Size of electrodes (antennas) and spacing – the Shark Shield antenna is designed to be have the most effect possible without compromising the user’s mobility. The dive model has larger electrodes, more widely spaced, and has a range of three to www.siliconchip.com.au five metres or so. There are two models of Shark Shield: the more powerful (4-5m range) DIVE01 unit is 21cm x 7cm x 3cm and weighs 590 grams (excluding electrodes and pouch). The combined total weight is about 1kg; and the GPSS01 (personal) unit is 17cm x 7cm x 3cm and weighs 450 grams (excluding antenna and pouch) The combined total weight is about 960 grams. Testing the Shark Shield SeaChange Technologies’ Technical Director, Mike Wescombe-Down. Thanks to Mike for his assistance with this feature. As we said before, a huge amount of laboratory and field testing has taken place before the Shark Shield was released to the market. Scientists know that sharks are much more intelligent than most people give them credit for (hence the success of shark netting). But that intelligence could just as easily have turned a “normal” shark into a dangerous predator. Much of the testing involved the use of shark bait and bloodied water. SeaChange Technologies used a variety of test floats and scenarios to ensure that the sharks would not associate a particular float (such as a surfboard) with a food source, even if much of the time they were repelled. The types of sharks tested included the “big three” mentioned above – great whites, bull sharks and tigers, but also included makos (known to become very aggressive and a threat to man) and, interestingly, the ocean white-tip shark. This particular shark is thought responsible for a huge number of attacks on sailors off sinking ships during World War II, attacking in packs and creating carnage. Testing will never stop Mike Wecombe-Down says that his company will continue to develop the Shark Shield and related products. “We have an ongoing program of testing and refining, at the same time looking at ways of adapting the technology for other uses.” “We’re already working on an electronic beach barrier, something that in time may replace beach netting. But the biggest problem to date has been not only getting sufficient energy to where it is required but making the package strong enough to withstand the forces of nature,” he said. Research and Development has commenced on variants of the Shark Shield, suitable for sailboarding, jet skiing, kayaking, boat protection and even a model for life jackets. A commercial range is also planned, which will include protection for aquaculture stocks and electronic beach barriers. Where, how much? Retail price of both units is about $700.00. The Australian and New Zealand distributors of the product are Aquanaut Pty Ltd (www.aquanaut .com.au); more information about the Shark Shield can be found on www. SC seachangetechnology.com.au The Shark Shield is a development of the earlier POD, originally used by divers in South Africa. May 2002  19