For Daniel Guerra, an aspiring Brazilian sailor keen to travel the world, the job ad was a dream come true. A British yacht owner was seeking two deck-hands to help sail his boat from Brazil across the Atlantic, one of the great ocean journeys. There would be no salary, but all expenses paid - and, crucially, Mr Guerra would gain some of the sailing experience he needed to qualify as a sea captain. "My dream was to become a captain and go work in Europe," remembers the 43-year-old, who saw the advert from an online sailing recruitment agency. "So I...