What exactly is the rules on a breakaway saftey switch? I know all of the smaller crafts require it but what about larger twin engine crafts? I know on all of the larger charter boats I have been on I have never seen them have a emergency kill switch that if they fell it would kill the boat. Also it doesn't appear that my 1976 Post 42' has or ever had one. Is there are year that was grandfathered in or is it a size/type of craft that requires them?