overlay-days

from The Century Dictionary.

• Nautical, a specified number of days that are agreed upon between the shippers and the master of the vessel (or her agent) for the loading and discharging of the cargo, beyond which number of days a stipulated per diem demurrage (forfeit) is agreed to be paid to the vessel. Sundays and holidays are not included unless the words “running days” are used in the charter-party (i. e., the written agreement), in which case all days are counted. Also known as lay-days.