I've been looking at the ships photo of all the damage and must say, a little concerned, especially if my family was on that ship. We were on the Sun Princess this past November and for the first time, we all mustered in the ships lounge verses the muster stations underneath the life boats. It took quite some time for everyone to get in and seated and even longer to exit.
This casualty demonstrates that mustering in the ship's lounges, etc., really is the right approach. In this case, passengers mustered on deck would have been (1) directly at risk and (2) potentially in the way of the efforts to fight the fire.
So, at what point were they considering lowering the life boats a putting passenger on them?
In this casualty, it's pretty clear that there was no intention whatsoever to evacuate passengers from the ship because the fire was mostly outside of the vessel. Rather, it appears that the crew lowered the boats in the vicinity of the fire part way to get them away from the fire. There are, of course, two reasons for doing this -- first, to ensure that the boats did not become part of the fire and, second, to get the boats out of the way of efforts to fight the fire. JTOL, this action also might have improved access to combat any spread of the fire into the boats, had that occurred.
If the fire kept on spreading downwards, you wouldn't be able to get on the boats and several passengers wouldn't have a way off the ship.
If the fire had continued spreading downward, they would have put the crews in the affected boats, lowered the boats in the affected area into the water, and detached them if necessry to protect them.
Had evacuation of passengers become necessary, they would have evacuated ALL passengers on the port side of the ship -- away from the fire. The boats from the starboard side would have maneuvered around the ship to the port side to take on evacuated passengers and crew.
If it took several hours to locate everyone, how long would it take to get everyone off?
About ten minutes. There's a huge difference in scope between checking names off of a muster list and putting people into lifeboats on a "first come, first served" basis. When the chivalrous chief of the muster statoin says, "okay, women and children first, follow me!" and heads out the door, the passengers would follow very quickly -- probably five or six abreast.
What kaos whould there of been if you lost all the life boats under the fire and had strand several hundred passengers because of it.
First, it's unlikely that they would have come anywhere close to losng all of the lifeboats.
Even if they did, however, it would not be a problem. There are actually enough life boats and inflatable life rafts (in the cylindrical cannisters that you see in racks along the rail) on each side of the vessel to accommodate everybody.
The Safety of Life at Sea (SOLAS) standards are way ahead of you.