Shark shield to protect swimmer

Marathon swimmer Penny Palfrey, who will attempt to set a world record by swimming from Cayman Brac to Grand Cayman next month, will have a shark shield to help protect her from some of the sea’s predators during 
her swim.

The Shark Shield is a shark-deterrent system that creates an electrical field that induces spasms in the sharks’ snouts.

“When I decided to swim from San Miguel Island to the mainland of California in 2008, I knew it was Great White Shark country,” said Ms Palfrey. “I had heard about the company called Shark Shield, and decided to contact them with regard to sponsorship in the loan of a Shark Shield unit for the swim 45 
kilometre swim.

“They generously obliged by lending me two units. Since then I’ve used Shark Shields on all my long ocean swims. They do give great peace 
of mind.”

Shark shields are used by swimmers, divers and surfers as they attach easily to a person’s ankle, are lightweight 
and compact.

“Many swimmers use them attached to their ankle, but they do cause some drag so I prefer to have the Shark Shield attached to my support craft,” Ms Palfrey said.

The shield will be attached to kayaks or paddleboards piloted by Richard Clifford and Jeff Kozlovich, who will accompany the swimmer during the crossing from the Brac to 
Grand Cayman.

Steve Munatones, a champion swimmer who will be on Ms Palfrey’s support team during the Australian swimmer’s Bridging the Islands swim in Cayman, said he has used it on other open water swims with Ms Palfrey.

“It is a proven, reliable piece of safety equipment,” he said.

“It is tied to the end of the kayak or paddle board that is near the swimmer, so the swimmer is within the protective range,” he said.

The Shark Shield offers a protective field of 26 feet radius, so to remain protected throughout the swim, the swimmer will need to stay relatively close to the kayak or paddleboard throughout her swim.

The shield is based on technology invented by the South Africa’s Natal Shark Board for the South African government. It is now used by the South African Navy, the Australian Elite Military, the US Coast Guard and is also approved by NATO, according to the manufacturer.

During two separate channel swims, Ms Palfrey encountered Great White Sharks and continued swimming.

The manufacturer, Shark Shield, produces a number of different kinds of the deterrent equipment, but the Freedom 7 shark shield is likely to be the one used during the Cayman Islands swim, Mr. Munatones said.

Its compact size and light weight means it is often used by divers in shark infested waters and that it will not create too much drag when attached to the kayak accompanying Ms Palfrey.

The unit includes a velcro pouch and a 7-foot-long flexible mesh antenna. Once the antenna is submerged in salt water, the electrodes emit the protective field.

The electrical field generated by the Shark Shield is detected by the shark through its sensory receptors known as Ampullae of Lorenzini, located on the snout of all predatory sharks. The pulsing sensation emitted by the shield does not replicate that given off by fish and does not attract sharks to an area.

Due to the length of Ms Palfrey’s attempt to swim between the islands – which is expected to take between 40 and 50 hours – the team will use two shark shields.

“Its battery life is between four and six hours, so we alternate two shark shields,” said Mr. Munatones. “While one shark shield is in the water, the other one is being charged in [Penny’s] escort boat.”

Ms Palfrey will swim the five miles from Cayman Brac to Little Cayman on 6 June, and then on 9 June will begin her 68-mile trek across the water between Little Cayman and Grand Cayman.

In April, Mr. Munatones, along with fellow Californian swimmer Lexie Kelly, who is working with the Flowers Group to organise the Flowers Sea Swim, swam together from Cayman Brac to Little Cayman, setting a new record of one hour, 53 minutes – a record they expect Ms Palfrey to beat.


  1. I sincerely wish for Ms. Palfrey to have a safe and successful swim, but have to say that most Cayman divers I know (and i know more than a few) would be more likely to wear a shark attractor than a shark repellant. Seeing a shark is one of the high points of any dive, and rather than being a source of fear or anxiety, an encounter with these majestic creatures is one of wonder, awe and beauty.

    Good luck Ms Palfrey and god speed!

  2. Ya highpoint. Until it starts gnawing on you, because you are splashing around and your heart beat sounds like a distressed fish, because she’s trying to swim hard.

    Yup…while my heart is beating fast, and im splashing around, I want to encourage sharks to approach me. Sounds absolutely reasonable. A high point of your trip through the open ocean.

    *shakes head slowly

  3. Listen, if sharks were all puppy dogs. They would never have invented any shark deterrent device to begin with. So obviously, there is a reason why this swimmer needs this device.

    Or is this just too much common sense for all you pro divers out there. Who think you are all obviously world renowned shark behavior analysists.

  4. Ms. Penny has a back-up system with the shark shield. One of her kayakers is a lawyer from NYC. So, the crew are expecting a bit of ‘professional courtesy’ out there.

  5. Obviously sharks can be dangerous but there is no need to heve the terrible fright and instant reaction to want to kill all sharks. I have dived with 100s perhaps 1000s of sharks and people are not the chosen food source of these creatures. I have dived with nurse, reef, black tip, lemon, hammerhead, tiger, silky, galapagos, white tip and silver tip sharks and never been experienced overly agressive behavior from a shark.
    Can and do sharks attack people? Occasionally, it is much more common to be struck by lightening than to be attacked by sharks.
    The macho adolescent desire to kill sharks is extremely offensive to me as they are an important part of a healthy marine ecosystem.
    Simply admit that sharks scare you and leave them alone, there is no need to kill them.

  6. Panama jack. You hit it on the head, you professional shark behavior analyst.

    YOU DIVE with sharks. In other words. Your heart is beating at a normal rate. You are calm and appear calm in the water, you are below the surface of the water.

    YOU ARE NOT ON THE SURFACE OF THE WATER SPLASHING AROUND WITH YOUR HEART POUNDING DUE TO EXCESSIVE EXERTION OF A RACE. The only reason the bottle water swim race isn’t in fear of sharks is because there are hundreds of people splashing around in a close area. which would make most sharks want to stay away.

    good god, this woman is alone in the water, talk about missing the differences, and then trying to say sharks are cool man.

    Dense is a good word I would use for anyone, saying sharks are safe man, don’t worry about it

    And read the darn story. no one is saying killing sharks it’s an electrical impulse that makes the swimmer appear to not be another fish.

    Yes….dense is a great description of those who are saying sharks are safe also from a reading standpoint too.

  7. The problem is that many people prefer to kill anything that they are afraid of including sharks. There are those who would kill all sharks. A safety net while swimming in open water for piece of mind is great.
    Killing sharks for fun, pleasure or feeling of machismo is pathetic.

  8. Dear cayCompass readers,
    Thank you for reading this article and your comments about my upcoming Bridging The Cayman Islands swim and the use of Shark Shields.
    I very much appreciate your support and share a passion with those who have a love the oceans and marine life.
    My swim’s expected to start in the middle of the night, go through dawn, the following day, through dusk, the following night, dawn again and well into the next second day.
    I’ve swum and dived with sharks in the past and have the upmost respect for them and all marine creatures. The Shark Shield does not harm sharks; it gives me piece of mind and allows me to concentrate on my swimming.
    Someday I would love to see the Shark Shield technology used to protect beaches instead of shark nets, thus saving the lives of many marine creatures such as sharks, whales, turtles and dolphins.
    Thank you again for your support, I’m very excited about my visit to your beautiful islands and swimming in the Cayman Islands.
    Penny Palfrey

  9. Penny Palfrey, I wish you luck in your swim and understand you wanting the peace of mind while swimming in open water especially at night. I never misunderstood the system hurt sharks rather I was speaking of those who hate sharks in general. You are amazing and I couldn’t imagine making such a swim.
    God bless you.

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