I'd have to agree with Walter on the "relying on the buddy" ideal. I don't seem to have much luck when it comes to buddies on dive boats whom I know nothing about. I pretty much rely on numero uno. The guy I was diving in the lake with, I dove with several times. He was solid.
But, I've had resort buddies that their tanks slip through the straps and try to bolt for the surface, guys that turn what's supposed to be a drift dive into a "grab the coral head and hang on" dive, guys that show me their spg at 500psi while mine reads 1500, guys that swim around like they're on commando missions, etc. etc...(I pretty much know I'm screwed when he can't figure out how to put his reg on the tank).
But I've also had some damn good ones too. Guys that would actually discuss a plan and follow it with me. Ladies too.
I think that rec diving off cattle boats can be downright dangerous sometimes, and all I want to do is relax and collect nitrogen when I'm on vacation. So I look forward to maybe a little solo diving somewhere in the near future, under the right conditions (brand new regulator, shore dive, calm seas, <50ft.)