Crazy, courageous, or something else, teens are casting off on a global sailing adventure.  With the most recent circumstance of Abby Sunderland, teen world circumnavigation is getting lots of press.  But this is not something new with the likes of Robin Lee Graham , who as a teenager set out to sail around the world alone, of 1965, and Tania Aebi who embarked on the same venture at 18 years of age in May, 1985.  Both achieved their goals and have e...