Some freighters are owner-operated. Others are on a time charter for a specified number of months. It is my understanding that there is a trend toward shorter charters. A charter can be renewed and the ship will retain its same itinerary. Sometime when the charter is renewed the charter party will not provide for passengers. Or, the itinerary can be changed to include different ports of call.

Some itineraries are very popular and can be booked for months, or even a year in the future. Accordingly, when you spot an itinerary that looks good, don't wait to book your trip. If you delay, the voyage may no longer be available due to the expiration of the charter, or because the itinerary has changed.

Your agent can advise you as to current or projected cabin availability. It is possible that the agent can put you on a wait list for a future voyage in the event the charter is expiring and the chances are good the charter will be renewed.

If you are wondering why charters are always changing it is because the charter party doesn't want to get locked in to a charter that costs ten to twenty thousand dollars a day on a long term bases and then be stuck with it when there is insufficient cargo to make the charter profitable.