Thone 1 - define 'prolonged' - in this case the risk management is a case of 'how long is a piece of string'? since the emergency (whatever it was) could strike at any stage you are outside your ability to reach land (autorotative range?)
How far offshore do you have to go to consider that safety equipment is a good thing? Just how lucky do you feel?
Why on earth would you fly over cold water with no safety equipment? Better to take twice as long and follow the coastline.