Reports of a fire in a lifeboat that blackened side of ship above it while in Cozumel the other day.
Unfortunately, the ship's boats do require flammable liquids -- their fuel. Proper handling of fuel should prevent this sort of incident, but the combination of spillage and some source of ignition (a cigarette tossed over the side from a balcony above and blown into the boat, for example) could cause this sort of fire.
It does appear that the fire was pretty well contained. A couple coats of fresh paint will take care of the black ont he side of the ship, and it's fairly easy to clean the balconies and to replace their furnishings. The repairs to the affected boat probably will be more extensive -- they actually might he to replace it.
BTW, modern cruise ships actually carry significant extra lifeboat and liferaft capacity so one boat out of commission won't disrupt operations.