Class surveys are periodic inspections conducted by classification societies to verify that a vessel continues to comply with the structural, mechanical, electrical, and safety standards required for its class notation. Classification societies — independent organizations such as Lloyd’s Register, DNV, Bureau Veritas, ClassNK, and the American Bureau of Shipping — establish and maintain technical rules for the design, construction, and ongoing maintenance of ships. A vessel must maintain its class to operate commercially, as flag states, insurers, port state control authorities, and charterers all require valid classification certificates.
Types of Class Surveys
The class survey cycle typically spans five years and includes several types of inspections. Annual surveys are conducted each year to verify that the vessel remains in satisfactory condition. Intermediate surveys occur around the midpoint of the five-year cycle and involve more detailed inspections of specific systems. The special survey (also called renewal survey) is the most comprehensive, conducted every five years, and may require extensive testing, thickness measurements, and even drydocking. Bottom surveys inspect the underwater hull and are conducted twice during the five-year cycle — once in drydock and once either in drydock or by in-water survey. Some classification societies also offer a Continuous Machinery Survey (CMS) scheme, allowing machinery items to be surveyed on a rolling basis rather than all at once.
Tracking Surveys with Software
Managing class survey requirements across a fleet is a significant logistical challenge. Each vessel has dozens of survey items with different due dates, window periods, and prerequisites. PMS and CMMS platforms track class survey requirements alongside routine maintenance, automatically flagging items that are approaching their due window and linking them to the relevant maintenance jobs and spare parts. This integration ensures that superintendents can plan drydocking periods and survey preparations well in advance, avoiding the costly consequences of class suspension — which can include loss of insurance coverage, detention by port state control, and rejection by charterers.