I think one of the bigger mistakes an owner does when trying a voyage like this is being over confidant about their vessel. They never had a problem, even in bad weather, and think that transposes to an open ocean voyage.
I can tell you that, given the perfect bad conditions, even the big guys in steel boats turn tail and run. I was on one trip from Houston to Alexandria Egypt where we calculated that we could have ridden a bike for that distance faster than it took us to cross the Atlantic and Mediterranean. It was not a pretty trip. And then there are the Cape rollers....big swells that lift tankers and crack the hulls.
Doing this voyage in a small sailboat is a true act of courage, single handed, nearly madness. I wish him the best--trailing winds and following seas.