In the last 500 years, there have been a total of 13 reported attacks on humans by blue sharks. Of those, only 4 were fatal. However, this does not mean they don't have a penchant for the delicacy of shipwrecked sailors.
They are known to feed on them, and are not timid in nature. Plus their penchant to hunt in packs makes them even more of a potential danger. They often will circle prey for up to 15 minutes, before taking an exploratory nibble of the target.