The slides, written out
AI-drawn illustration. Simplified to explain the idea, not to scale.
Slide 1 · HSSC &
HSSC &
CAS EXPLAINED
A Chief Officer's Practical Guide
Survey Planning • Hull Condition • Statutory Compliance
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Slide 2 · HARMONIZED SYSTEM
HARMONIZED SYSTEM
OF SURVEY & CERTIFICATION
(HSSC)
Before the Harmonized System of Survey and Certification (HSSC) entered into force on 3 February 2000, different certificates under different IMO conventions had different survey windows and validity periods.
What is HSSC?
A common survey framework that harmonizes statutory surveys under SOLAS, MARPOL and Load Line conventions.
KEY FEATURES
Common 5-year certificate cycle
Annual surveys
Intermediate survey within 3 months before or after the 2nd or 3rd anniversary date*
Renewal survey every 5 years
Common anniversary date**
Better survey planning & coordination
* Depending on the applicable certificate.
** The day and month corresponding to the expiry date of the certificate.
HSSC 5-YEAR SURVEY CYCLE
YEAR 2/3
YEAR 4
YEAR 5
Annual Survey within 3 months before or after the anniversary date
Intermediate Survey within 3 months before or after the 2nd or 3rd anniversary date*
Annual Survey within 3 months before or after the anniversary date
Renewal Survey within 3 months before or after the anniversary date
Bottom inspections are carried out in accordance with the applicable statutory and classification society survey requirements.
WHY CHIEF OFFICERS CARE
Easier dry-dock and survey planning
Reduces number of surveyor visits
Better coordination with Class & Flag
Helps maintain Port State Control compliance
Slide 3 · CONDITION
CONDITION
ASSESSMENT SCHEME
(CAS)
A strengthened structural assessment required for certain eligible single-hull oil tankers operating under MARPOL Annex I phase-out provisions.
Purpose
To demonstrate that the hull structure of an eligible single-hull oil tanker is fit for continued safe operation beyond the normal phase-out date.
WHAT CAS INVOLVES
Close-up structural inspections
Thickness measurements
Pressure testing
Coating assessment
Structural review
Flag Administration review and authorization
AREAS OF FOCUS
Cargo Tanks
Cargo Tanks
Ballast Tanks
Thickness Measurement Points
Close-up Inspection Locations
CHIEF OFFICER RESPONSIBILITIES
Ensure tanks are cleaned and safe for inspection
Provide safe access and proper lighting
Maintain coating condition records
Prepare for thickness measurements
Assist surveyors during all stages of CAS
IMPORTANT NOTE
If the tanker does not meet the CAS criteria, the Flag Administration may not authorize it to continue operating beyond the phase-out date.
Slide 4 · PRACTICAL TAKEAWAYS
PRACTICAL TAKEAWAYS
Understanding the Difference. Ensuring Compliance.
HSSC vs CAS – AT A GLANCE
Aspect | HSSC | CAS
What it is | A survey scheduling system that harmonizes statutory surveys and certificates. | A structural assessment programme for eligible single-hull oil tankers.
Purpose | Ensures timely surveys and validity of statutory certificates. | Demonstrates continued structural fitness beyond the phase-out date.
Applies to | All ships covered under SOLAS, MARPOL and Load Line conventions. | Certain eligible single-hull oil tankers under MARPOL Annex I phase-out provisions.
Cycle / Timing | 5-year certificate cycle with annual and intermediate surveys around the anniversary date. | Conducted when required under the phase-out provisions and approved by the Flag Administration.
Focus | Survey planning, inspection and certification. | Detailed hull structure inspection, measurements and testing.
Outcome | Keeps the ship compliant and certificates valid. | Confirms structural fitness for continued safe operation.
CHIEF OFFICER CHECKLIST
Review survey schedule and anniversary dates.
Ensure all statutory certificates are valid.
Plan surveys well in advance and coordinate with Class.
Prepare tanks and spaces for inspection and ensure safe access.
Maintain coating condition and thickness measurement records.
Assist surveyors and address findings promptly.
Verify that the ship remains compliant with SOLAS and MARPOL requirements.
KEY MESSAGE
Good survey preparation reduces delays, improves compliance, and supports safe & efficient vessel operations.
Plan early. Prepare well. Stay compliant. That's the Chief Officer's advantage.
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Drafted by SailR from our daily lessons. AI-drawn illustration. Simplified to explain the idea, not to scale. Last updated 19 Oct 2026.
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