Granny attempts Cuba-US swim without shark cage

British-Australian swimmer Penny Palfrey launched Friday a historic attempt to swim unassisted from Cuba to the United States, seeking to become the first do so without a shark cage. The 49-year-old mother of three and grandmother of two jumped into the sea shortly after sunrise at 7:03 am (1103 GMT) from the Hemingway International Yacht Club in western Havana, headed for Florida\'s Key West. The swim was expected to take between 40 and 50 hours. \"A little excited, a little nervous,\" Palfrey told reporters before diving in. \"Beautiful sea, beautiful sunrise.\" The swimmer arrived at the dock under a clear sky wearing a blue bathing suit, gray cap and goggles, her face, legs and arms lathered with sunscreen. She waved an Australian flag. \"Swimming strong. Great conditions. Some jellies, but not bad,\" Palfrey\'s support team tweeted after she covered 2.06 nautical miles (3.81 kilometers) in her first hour. And after about four hours, she had covered about 7.5 miles. \"Cuba fading on horizon. Looking good,\" her team said in another tweet. She crossed the Tropic of Cancer at 12:43 pm (1643 GMT), after about five hours and 40 minutes of swimming, it added. Palfrey is seeking to accomplish the feat in a \"call for friendly relations between the peoples of the United States and Cuba,\" according to the Cuban foreign ministry. Cuba\'s national commissioner for swimming Rodolfo Falcon told AFP that if Palfrey succeeds, \"it will be something out of this world.\" \"Sea conditions are not similar to the pool, where she trained for many hours. At sea, the salt water weighs you down,\" said Falcon, a silver medal winner at the 1996 Olympic Games. Susie Maroney, a former Australian marathon swimmer, swam from Cuba to Florida in 1997 when she was just 22, but she used a shark cage. Veteran US endurance swimmer Diana Nyad, 62, has tried, and failed, to complete the trek three times, twice without a shark cage. Her latest attempt was in September, when she quit her swim two thirds of the way into the crossing after suffering dangerous jellyfish stings. She plans to try again this summer. Two yachts, a kayak and a boat are part of Palfrey\'s support team, which includes her husband Chris. The vessels are carrying ultrasound equipment to ward off sharks. Palfrey, who was born in Britain and moved to Australia at age 19, is among the most accomplished open-water swimmers in the world and has successfully completed swims in the Caribbean and Pacific without a shark cage. Two years ago, she crossed the Strait of Gibraltar between Spain and Morocco in three hours and three minutes, setting a new record for women. Last year, Palfrey -- who began swimming at age nine -- swam from Little Cayman to Grand Cayman Island, again without a cage.