Source: US Department of Transportation, Maritime Administration.
The distribution of cruises by the number of days shows very specific characteristics of cruise itineraries. The share of cruise lasting 7 days is dominant (47%) with other prevalent duration in the range of 3 to 5 days. This illustrates a scheduling issue for cruise shipping lines as they maximize their asset utilization through a continuous turn of cruise ships. For instance, a ship usually finishes a weekly cruise early in the morning and begins a new one on the evening of the same day. In the 8 to 12 hours window between the end of the inbound cruise and the beginning of the inbound cruise passengers must check out and disembark, facilities are cleaned, waste discarded, stores replenished, the ship refueled, basic maintenance performed and outbound cruise passengers must check-in and embark. The design variables of itineraries within this time frame mainly concern the number and order of port calls, the synchronization with the (international) air transfers at the turn ports, vessel speed, and vessel size.