def give them a handle to make them feel safer. remember you have a steering wheel to hang on to. but most importantly NEVER do something that makes your passenger feel unsafe. you might have a blast going balls out down the river but your passengers bouncing around in their seats dont want to say that they're really frightened. they might not understand that they're only going 60-80mph... your mind being that close to the water in a low freeboard boat makes it feel like 200mph.
ive done some STUPID shit in my times with my cars by myself and lived to tell the tales... and the ONE TIME i got tossed into a 180* spinout my wife was in the back seat laying down. im super lucky she wasnt tossed out, into the side/motor/etc. handle or not, shit happens.