That mostly involves one of two scenarios, referred to in the industry as “warm” or “cold” layup.

In warm layup, most systems are kept functioning; in cold layup more are shut down, such as ballast tanks, turbines, and gear boxes. Cold layups come with extra precautions, too, such as sealing off external doors and windows, moving linens to a dry place, putting mattresses on edge, opening all dresser drawers and closets, and sealing bathroom fixtures, to name a few.

An advantage to warm layup is ships can quickly be put back into operation. Once the word comes down, Burke says, the ship can resume carrying guests within weeks—though it will still need to get a full crew onboard and sail to the appropriate destination.

But warm layup requires more upkeep, and therefore more staff. Each ship has a “safe manning” team—about 120 crew members for a large ship. Among the necessary personnel, according to Carnival’s Burke: a deck crew to drive the ship, an engineering crew to run the electrical power and propulsion, a medical team to tend to staff needs (particularly in the time of Covid-19), security, and enough housekeeping and kitchen staff to keep everyone looked after and fed.

In the event of hurricanes or other bad weather, the ships have to be able to move. They also have to comply with environmental, safety, and other regulations or risk stiff fines, criminal charges, and other penalties, says Burke. In 2016, for example, Carnival received a five-year probation and a $40 million fine on a criminal pollution conviction.

But there’s a time limit on this half-on strategy: According to shipping analysts at maritime intelligence company Lloyd’s List, warm layup is only appropriate in the short term. After as little as six months, ships may lose certain certifications that allow them to sail legally.

A Ship Out of Water
Cold layups require fewer systems to run, and therefore, as little as 40 crew members: a bridge team, engine room operators, fire wardens, and hotel staff. But grinding operations to a near-halt makes it more difficult and expensive to restart. According to Lloyd’s Register’s layup guide, every corner of a ship, from the pump room to the living quarters, needs to be inspected for things like gas leaks and mold; electrical equipment, including the navigation systems, need to be removed from safe storage and reinstalled ; and dehumidifiers all need to be removed before furniture and soft goods can be cleaned and put back in place. That’s why cold layups are seen as advantageous only in the event of an outage stretching to many months. 

Burke says Carnival could move in this direction in the long term. According to Mathisen, Royal Caribbean has already committed to this tact. Its fleet is largely being protected by dehumidifiers—deployed everywhere from engine rooms to public areas.

When they’re ready to set sail again, the restart “can take weeks to months,” he explains, detailing delays that range from transporting crew back to the ship, going through bureaucratic recertification processes, or even financing expensive dry dock repairs.

A more drastic option is tying up the ship, shutting down all systems, leaving only some emergency generators running and a few fire safety crew and watchmen on duty. Cruise historian and writer Peter Knego paints a grim picture of what can happen in that scenario.