Surveys, audits and PSCLesson 1 of 7
Statutory certificates and the survey windows (HSSC)
You will be able to read any ship's certificates, work out every survey window, and know what a missed window or an extension really means.
15 minutes · Open to everyone · Rules checked 20 October 2026
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A ship can be in perfect condition and still be detained for paperwork that is simply out of date. The reason is almost always the same: someone misread a survey window. Each statutory certificate is valid only as long as its surveys are done inside fixed time windows. If the annual survey of the Cargo Ship Safety Equipment Certificate is not completed within three months of the anniversary date, the certificate stops being valid, even if every lifeboat and fire extinguisher on board is perfect.
The rules behind those windows are the Harmonized System of Survey and Certification (HSSC). It was written into SOLAS and the Load Line Convention by their 1988 Protocols, later into MARPOL, the Ballast Water Management Convention and several codes. The IMO explains how to apply it in its Survey Guidelines, which the Assembly revises about every two years.3 The version in force today is resolution A.1207(34), the Survey Guidelines under the HSSC, 2025, adopted on 3 December 2025. It revoked the 2023 version, resolution A.1186(33).
Try it
One five-year cycle of a cargo ship's statutory surveys
In plain words
Think of each certificate as a five-year ticket with a yearly check-up. The ticket is issued after the first full survey. Every year, on or near the date printed on it, a surveyor comes back to see that nothing has slipped. Halfway through, one of those yearly visits is a deeper one. At the end of five years, a full survey renews the ticket.
Each yearly check has a six-month window: three months before and three months after the “anniversary date”. The anniversary date is the day and month of the certificate’s expiry date, repeated every year. If the expiry date is 15 March 2029, the anniversary date is 15 March of each year, and the annual survey can be done from 15 December to 15 June.
Renewal is different. It can be done in the three months before expiry without losing time on the new certificate. Done earlier than that, the new certificate starts from the day the survey ends, so you lose a few months of validity.
Two rules surprise people. First, a missed window does not just mean a late survey: the certificate stops being valid until the missing survey has been done. Second, an extension is not a right. Only the flag Administration can grant it, only to let the ship finish its voyage to the port where it will be surveyed, and only for a short time.
In detail
Which certificates follow the HSSC
The HSSC covers the main statutory certificates: under SOLAS the Cargo Ship Safety Construction (code C), Safety Equipment (E) and Safety Radio (R) Certificates, or the single Cargo Ship Safety Certificate that can replace all three, and the Passenger Ship Safety Certificate (P); the International Load Line Certificate (L); the MARPOL certificates for oil (O), noxious liquids (N), sewage (S) and air pollution (A); the Ballast Water Management Certificate (B); the IBC and IGC certificates of fitness (D, G); the Polar Ship Certificate (W); and the Industrial Personnel Safety Certificate (T). The letter codes are the ones the Survey Guidelines use for each survey item, for example “(EA)” for the annual survey of the Safety Equipment Certificate.
The survey types
| Survey | What it is | When |
|---|---|---|
| Initial | Complete inspection, plan review, documents on board | Before the ship enters service, or when a new instrument first applies |
| Annual | General inspection, certificate check, some tests | Within 3 months before or after each anniversary date |
| Intermediate (C, and MARPOL, BWM, IBC/IGC) | Inspection of specified items, deeper than annual | Within 3 months of the 2nd or 3rd anniversary date, replacing one annual |
| Periodical (E) | Inspection with tests of the safety equipment | Within 3 months of the 2nd or 3rd anniversary date, replacing one annual |
| Periodical (R) | Radio installation survey | Within 3 months of each anniversary date |
| Renewal | As periodical, plus a new certificate | Before the certificate is renewed; ideally in the 3 months before expiry |
| Bottom inspection (cargo ships) | Underwater hull and related items | At least two in five years, maximum 36 months apart |
| Additional | General or partial survey | After an investigation, important repairs or renewals, or a BWMS retrofit |
The Passenger Ship Safety Certificate is different: it is valid for no more than 12 months and is renewed every year. A passenger ship needs at least two bottom inspections in dry dock in any five-year period, never more than 36 months apart, although for passenger ships that are not ro-ro passenger ships the Administration may accept one dry-docking in five years if in-water surveys meet IMO criteria.
Working out the windows
Take a Cargo Ship Safety Equipment Certificate with an expiry date of 15 March 2029.
| Event | Window |
|---|---|
| 1st annual survey | 15 Dec 2024 to 15 Jun 2025 |
| 2nd anniversary: annual, or periodical | 15 Dec 2025 to 15 Jun 2026 |
| 3rd anniversary: periodical, or annual | 15 Dec 2026 to 15 Jun 2027 |
| 4th annual survey | 15 Dec 2027 to 15 Jun 2028 |
| Renewal without losing validity | 15 Dec 2028 to 15 Mar 2029 |
Only one of the 2nd or 3rd anniversary surveys is the periodical; the other is an annual survey. Owners often choose the year in which the ship is in dry dock. The construction certificate’s intermediate survey uses the same windows. For the bottom inspections, remember the 36-month cap: if the first one is done early in the cycle, the cap may stop the certificate from being extended later.
Renewal timing and the new certificate’s dates
- Renewal completed within 3 months before expiry: the new certificate runs to five years from the old expiry date.
- Renewal completed more than 3 months before expiry: the new certificate runs for up to five years from the completion date, so the months between are lost.
- Renewal completed after expiry: the new certificate still dates from the old expiry date, unless the Administration applies “special circumstances”, which the Guidelines limit to ships laid up or out of service for a long period because of major repair or modification.
Extensions
If the certificate expires while the ship is not in a port where it is to be surveyed, the Administration may extend it by up to three months so the ship can complete its voyage. A ship on short voyages, meaning neither the outward nor the return voyage is longer than 1,000 miles, may be given up to one month. On arrival in the survey port the ship may not leave without a new certificate, and the new certificate is dated from the original expiry date, not the extended one.
When the survey simply cannot be finished in the port where the ship is, the Guidelines recommend conditions: an additional survey at least as wide as an annual survey, the renewal survey done as far as possible, an underwater (or at least internal) bottom inspection if a dry-docking is due, a named voyage to the discharge port and then to the survey port, and the shortest possible extension.
When a window is missed
The Guidelines call this revalidation. A certificate ceases to be valid if the annual, intermediate or periodical survey, or the bottom inspection, is not done within its window. Validity is restored by doing the missed survey, with thoroughness that reflects how long it was allowed to lapse, and the Administration should find out why it happened. In a port State inspection, an invalid certificate is a classic ground for detention.
Other events that change certificates
- Accident or defect: the master or owner should report it at the earliest opportunity to the Administration or the RO that issued the certificate, which decides whether an additional survey is needed.
- Survey shows deficiencies that cannot be fixed now: if the ship is still fit to proceed, the surveyor issues a condition with a due date. If it is not fit, corrective action is needed at once or the certificate is withdrawn.
- Change of flag: all certificates cease to be valid. The new flag may issue new certificates with the same expiry dates once satisfied the ship has been maintained.
- Radio and AIS: the radio survey and the annual AIS test must be done by a qualified radio surveyor using suitable test equipment.
Remote surveys
A remote survey uses two-way video and a competent crew member or service technician to show the surveyor the item. The 2025 Guidelines allow it in place of an attended periodical, annual or intermediate survey only in extraordinary circumstances (natural disaster, war, pandemic, strike and similar) and only after a case-by-case assessment approved by the flag Administration.
What is coming
At its 12th session in July 2026 the III Sub-Committee agreed to give every survey item in the HSSC Guidelines a code saying whether it may be surveyed remotely, with the explanatory text still to be written.6 The Assembly revises the Guidelines about every two years, so expect a further version after the 2027 Assembly session.3
Work it out
What the rules say
- SOLAS chapter I regulations 7 to 10 set out the surveys for passenger ships, life-saving appliances and other equipment, radio installations and structure, machinery and equipment of cargo ships, and regulation 14 sets the duration and validity of certificates.2
- The Survey Guidelines under the HSSC, 2025 (resolution A.1207(34)) revoke resolution A.1186(33) and take account of amendments in force on or before 31 December 2025.1
- Paragraph 1.3 of the Guidelines provides for completion of the renewal survey “within three months before the expiry date of the existing certificate with no loss of its period of validity”, a six-month window for annual, intermediate and periodical surveys, and extensions limited to three months, or one month for short voyages.1
- Paragraph 4.3.1 places the intermediate survey within three months before or after the second or the third anniversary date, in place of one of the annual surveys.1
- Paragraph 4.4.1 places the safety equipment periodical survey within three months before or after the second or the third anniversary date, and the safety radio periodical survey within three months of each anniversary date.1
- Paragraph 4.6 requires at least two inspections of the outside of the bottom of a cargo ship in any five-year period, no more than 36 months apart, with bulk carriers and oil tankers of 15 years and over inspected in dry dock.1
- Paragraph 5.6 states that a certificate “ceases to be valid” if the annual, intermediate or periodical survey or the bottom inspection is not completed within its period.1
- Paragraph 5.4 defines a short voyage as one where neither the outward nor the return voyage exceeds 1,000 miles.1
- Paragraphs 5.11 and 5.12 require radio and AIS surveys to be carried out by a qualified radio surveyor with suitable test equipment.1
- Paragraph 5.15 allows remote surveys only in extraordinary circumstances, after a case-by-case assessment approved by the flag Administration.1
- Under the Procedures for Port State Control, the lack of valid certificates required by the conventions may warrant detention.4
Flag and class notes
Extensions and remote surveys are decisions of the flag Administration, not of the ship or the class surveyor on board, unless the flag has formally authorised its RO to grant them. Ask early: most flags expect a written request from the company with the reason, the voyage plan and the RO’s recommendation, and they apply the conditions in paragraph 5.9.2 of the Survey Guidelines.1 Flags publish their policies as circulars and technical alerts on their websites: Panama, for example, keeps its Merchant Marine Circulars at panamashipregistry.com/circulars, and the Bahamas Maritime Authority publishes Technical Alerts.78 When the RO also classes the ship, class survey dates (special survey, docking survey, continuous survey items) are usually harmonised with the statutory windows. Check the ship’s class status report for any conditions of class or statutory conditions with a due date.
Key numbers
| What | Value |
|---|---|
| Annual, intermediate and periodical survey window | 3 months before to 3 months after the anniversary date1 |
| Renewal survey without loss of validity | Within 3 months before expiry1 |
| Maximum validity, cargo ship certificates | 5 years1 |
| Maximum validity, Passenger Ship Safety Certificate | 12 months1 |
| Extension to complete a voyage | Up to 3 months1 |
| Extension for ships on short voyages | Up to 1 month1 |
| Short voyage | Neither leg over 1,000 miles1 |
| Bottom inspections, cargo ship | At least 2 in 5 years, max 36 months apart1 |
| Bottom inspection in dry dock compulsory | Bulk carriers and oil tankers of 15 years and over1 |
What inspectors find
- Certificates whose annual or intermediate endorsement was never signed, so the certificate is no longer valid. In 2025 the Tokyo MOU recorded 1,617 deficiencies against ship certificates and 3,472 against other documents.5
- A Record of Equipment (Form E or Form C) that does not match the ship: a liferaft or lifebuoy changed, a new EPIRB fitted, but the record never updated.
- Damage from a contact or heavy weather that was not reported to the flag or RO. The PSC Procedures only spare a ship from detention for accidental damage if it was notified and is being dealt with.4
- Overdue conditions of class or statutory conditions, found when the PSCO checks the class status.
- An extension letter that the ship cannot produce, or one used for a voyage other than the one approved.
Questions people ask
What exactly is the anniversary date?
The day and month of each year that correspond to the certificate’s expiry date. It is not the date the certificate was issued.
Can we do the annual survey early to suit the schedule?
Yes, within the window it is simply an annual survey. Doing it before the window opens may have consequences for the anniversary date and later surveys, so agree it with the RO and flag first.
Does the radio periodical survey move with the equipment periodical?
No. The safety radio periodical survey is due within three months of every anniversary date, every year.
The ship is in dry dock in year two. Is that enough for both bottom inspections?
No. You need a second one in the five-year period, and one must be on or after the fourth annual survey with the renewal, with no more than 36 months between them.
Is a remote survey an option if no surveyor can attend?
Only in extraordinary circumstances and with the flag’s case-by-case approval. Normal schedule pressure is not enough.
Check yourself
6 questions. Pass with 60% to mark the lesson as done.
Sources
- 1 IMO Resolution A.1207(34), Survey Guidelines under the Harmonized System of Survey and Certification (HSSC), 2025 (adopted 3 December 2025, re-issued 16 January 2026), Annex, General sections 1 to 5. https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2034-Res.1207%20-%20SURVEY%20GUIDELINES%20UNDER%20THE%20HARMONIZED%20SYSTEMOF%20SURVEY%20AND%20CERTIFICATION%20(HSSC),%202025%20(Secretariat).pdf
- 2 International Convention for the Safety of Life at Sea (SOLAS), 1974, as amended, chapter I, regulations 7, 8, 9, 10 and 14 (IMO publication). https://www.imo.org/en/About/Conventions/Pages/International-Convention-for-the-Safety-of-Life-at-Sea-(SOLAS),-1974.aspx
- 3 IMO, Harmonized System of Survey and Certification (HSSC), overview page. https://www.imo.org/en/ourwork/iiis/pages/harmonized%20system%20of%20survey%20and%20certification%20(hssc).aspx
- 4 IMO Resolution A.1185(33), Procedures for Port State Control, 2023, paragraph 2.3.7 and appendix 2, section 4 (superseded by resolution A.1206(34), Procedures for Port State Control, 2025, adopted 3 December 2025, whose core chapters are unchanged). https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2033-Res.1185%20-%20PROCEDURES%20FOR%20PORT%20STATE%20CONTROL%2C%202023%20(Secretariat)%20(1).pdf
- 5 Tokyo MOU, Annual Report on Port State Control in the Asia-Pacific Region 2025, table of deficiencies by category. https://www.tokyo-mou.org/wp/wp-content/uploads/ANN25.pdf
- 6 ABS, Brief: IMO Sub-Committee on Implementation of IMO Instruments, 12th session (III 12), July 2026. https://ww2.eagle.org/en/rules-and-resources/regulatory-updates/regulatory-news/iii-12.html
- 7 Panama Maritime Authority, Merchant Marine Circular MMC-379, Procedure for Port State Control, 2025 amendments (updated July 2026). https://www.panamashipregistry.com/wp-content/uploads/2024/07/MMC-379-Procedure-for-PSC-2025-30-07-2026.pdf
- 8 Bahamas Maritime Authority, Technical Alert 26-04, IMO Procedures for Port State Control 2025 (3 March 2026). https://www.bahamasmaritime.com/wp-content/uploads/2026/03/TA004-IMO-Procedures-for-Port-State-Control-2025.pdf
Free awareness training. Al Safwan Marine is not an approved training provider, so no certificate is given, and these courses are not a qualification. They don't replace STCW training, manufacturer training or the certification technicians need for this work. The manufacturer's manual and your flag's rules always come first.
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