What does the harmonized system provides ?

A  one-year standard interval between surveys, based on initial, annual, intermediate, periodical and renewal surveys as appropriate; a scheme for providing the necessary flexibility for the execution of each survey with the provision that the renewal survey may be completed within three months before the expiry date of the existing certificate with no loss of its period of validity;
a maximum period of validity of five years for all certificates for cargo ships a maximum period of validity of 12 months for the Passenger Ship Safety Certificate; a system for the extension of certificates limited to three months to enable a ship to complete its voyage (or one month for ships engaged on short voyages);
When an extension has been granted, the period of validity of the new certificate is to start from the expiry date of the existing certificate before its extension.

SUMAN KUMAR