Two Florida brothers, Ralph and Robert Brown, will take to the high seas on the world's longest trans-Atlantic voyage in a 21-ft flats boat on June 27 to raise $3m for military charities in the name of fallen Marines. The I Am Second Wounded Hero Voyage Crossing the Atlantic Presented by Interstate Batteries will embark on a 48-day, 6,200-mile trip from Tampa, Fla., to Hamburg, Germany that includes 20 stops along the North American and European Atlantic coasts. The Browns will use the Intruder-21, the same vessel which landed them in the "Guinness Book of World Records" in 2007. The pair is out to prove the humble boat they designed and built, capable of sailing in two inches of water, can also weather the rough Atlantic seas.