i agree it can be a bit scary as well, however after your first trip the captains send hank an informal eval of you. For the most part hank knows the captains and once you are a member he will give you honest feedback about weather that particlar captain would be a good fit. Hank does the same for the captains.
It really is a great way for people to get experience, honestly i have learned more from my opo experience and sailed more with opo than i did when i had my own boat.
If you don't know people to crew with you or if your looking to crew i can honestly say this is the best and "safest" way to go. It certainly beets all the adds by male captains here "looking for female crew"...great fantacy but jesus get real.
OPO is really a great service.