I can tell you that safety is something that is more often than not overlooked until something really bad happens (I will use Dale Earnhardt as an example) the problem is its always something that could always have happened, but rarely does. I think NASCAR has answered this question to the absolute and with numerous other consequences, but anybody that has seen the Micheal McDowell crash last month cannot deny that what NASCAR has done is to build a safer car (COT).
The problem with being locked into the boat in any form I believe will introduce a whole new set of dangers, mainly because it is hard to make the determination on when you don't want to get thrown from the boat, sometimes that is what saves major injuries, and sometimes causes them. Someone would really have to look at all of the serious crashes and first look at what would have to be done to prevent them (possibly limit HP thus limiting speed) I don't know.
The Whitewater Jetboat Assoc. has done an exellent job in rule changes in regards to safety, but there is always room for improvement. An example would be that these guys are literally buckled in a 120+MPH jet boat with a rollbar that runs for several miles and there are only a dozen or so chase boats, think about it what if you flip somewhere they don't expect you to? If you're knocked out, you're done for.....
I am a firm believer in safety, but sometimes its a be careful what you wish for scenario.
The enclosed capsule is probably F1 and boat drag racings greatest safety "shining moment" but IMO more needs to be done in other areas of boat racing, I just don't know what......
I came out of a river boat at over 80MPH in about two feet of water (spun out) and can tell you being buckled in with a roll bar would have been the ticket. (happened before the roll bar rule).
IMO there is no way possible to prepare for every scenario, that's why we call them accidents....
BTW ever wear a Haans?, you can't move your head to see, that IMO would cause more crashes than it would protect against (with the exeption of stright line stuff). The best safety equipment is sitting on top of our necks...