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.