A comprehensive five-yearly classification survey requiring drydocking and full structural inspection to renew class for a further five years.
In practice
For tankers and bulk carriers under the ESP programme (IMO A.744(18)), the special survey requirements are particularly extensive, with mandatory close-up surveys of all cargo tank or hold structural members, a defined programme of thickness gauging comparing measurements to as-built drawings, and assessment of coating condition. The technical superintendent typically produces a comprehensive repair specification months in advance, obtains competitive shipyard tenders, and manages a project team aboard the vessel during the drydock period. Special surveys are major capital expenditure events, and their timing profoundly affects the commercial scheduling of the vessel.
Regulatory detail & full definition
A special survey is the comprehensive five-yearly classification survey required to renew a vessel's class for a further five-year period. It represents the most demanding examination a vessel undergoes in its operating life and requires drydocking — or, for some vessel types, an approved in-water survey — to allow inspection of the entire hull, underwater appendages, sea valves, rudder, and propeller. The scope of the special survey includes close-up examination and thickness gauging of structural members throughout the hull, pressure testing of tanks, overhaul of steering gear and anchor equipment, and survey of all class-required fittings.
For tankers and bulk carriers under the ESP programme (IMO A.744(18)), the special survey requirements are particularly extensive, with mandatory close-up surveys of all cargo tank or hold structural members, a defined programme of thickness gauging comparing measurements to as-built drawings, and assessment of coating condition. The technical superintendent typically produces a comprehensive repair specification months in advance, obtains competitive shipyard tenders, and manages a project team aboard the vessel during the drydock period. Special surveys are major capital expenditure events, and their timing profoundly affects the commercial scheduling of the vessel.