The swath that Hurricane Isaac is cutting through the waters of the Gulf of Mexico won't be hitting any cruise ships, but it has already affected some ship itineraries…with more to come.
When the storm hits New Orleans today, whatever damage is left behind could affect two Carnival ships, the Conquest and the Elation. The latter is supposed to be returning on Thursday to drop off passengers who have been in the Western Caribbean and pick up a new load before leaving that evening. The Conquest isn't due back until Saturday from an Eastern Caribbean cruise.
The other two ships that home-port in New Orleans, the Norwegian Star and Royal Caribbean's Navigator of the Seas, won't be there until November.
As for damage done — minor for cruisers considering the big picture — Tropical Storm Isaac forced the Port of Miami to be closed on the weekend, leaving four ships at sea longer than planned: Norwegian's Sky, Royal Caribbean's Majesty of the Seas and Carnival's Imagination and Valor. Allure of the Seas was also two days late getting back to Fort Lauderdale.
All five ships are on shorter cruises this week as a result, and three of them had to change itineraries.
As you probably know, the risk of seeing a cruise ship caught in a hurricane is minute, because the weather systems are monitored closely and because cruise ships travel faster than hurricanes.
Considering what the poor folks of the Gulf Coast (and other places) face, hurricanes like Isaac are not much more than a nuisance to people on cruise ships.

Holland America Eurodam
7 nights
November 24, 2012
Fort Lauderdale (return): Grand Turk, San Juan, St. Thomas, Half Moon Cay
Inside: $499
Cost per day: $71
www.hollandamerica.com