Laid-up vessels are vessels that are temporarily out of service due to a shortage of cargo or that are temporarily removed from commercial service. Ships are laid up, for example, when freight rates are insufficient to cover running costs. In times of economic crisis, lay-up is often preferred over selling the vessel.
In this decommissioning state, the machinery is kept in service in the interest of rapid return to service, but measures may be taken to reduce various operating costs. Since the machinery, life-saving equipment, and navigational equipment are all well maintained, and up to date, the ship can be returned to service very quickly. Vessels should normally be laid up without cargo.
During cold lay-up, the engines are taken out of service, and the ship is kept "electrically dead" except for the emergency power supply. Accordingly, when a ship enters cold lay-up, as many parts of the ship as possible are shut down to save costs. This condition usually requires a return to service time of 3 weeks or more, depending on the degree of preservation and maintenance performed during decommissioning.
The degree of preservation is based primarily on the age and value of the vessel and the most likely scenario for recommissioning. Examples of scenarios include:
- vessel returns to normal trade
- Ship sails to repair yard
- Vessel proceeds to the scrapping yard.
Regarding crew, the number of workers on board is drastically reduced. During a warm lay-up, the engine department and deck department are nearly fully staffed. In contrast, during a cold lay-up, there is minimal skeleton crew available to step in to refloat the ship in an emergency (e.g., a hurricane). Minimum manning for fire, spill, berth, and safety watches should be maintained. The berth is usually in a remote location, so access is limited. Power is kept to a minimum, for example, to ensure the operation of the windlass and mooring winch.
Depending on how long the company intends to decommission the vessel, different approaches may be taken to maintain the vessel's interior. For a lay-up period of three to nine months, the air conditioning system will continue to run to keep humidity levels down. However, for a longer lay-up period, the rooms will be hermetically sealed.