Naaghh Maybe not!
Now I don't claim to be a qaulified Captain (well of ferries anyway) but I would think the first rule in ocean safety would be close the doors before we set off?
Or if you must transport a truck load of flammable fluid on a passenger/car ferry then have someone standby with a fire extinguisher?
Oh well, the Greenstump rule of ferry travel remains.
Park the vehicle, quick as possible to the top deck, pick your jumping off spot, carry a two litre plastic drink bottle as it provides more than enough flotation for someone who can swim more than 50M.
Don't bother with the Life Buoys as they are normally triple knotted to the ship to stop people knocking them off. This of course can be hassle if the ferry sinks in water deeper than the rope reach to the Life Buoy.