Operational Guide · Registers & Logbooks

# International Load Line Certificate

The Plimsoll mark on the hull is not decorative: it represents the limit beyond which the ship, according to the freeboard calculation, no longer has a sufficient safety margin.

Load Line Plimsoll freeboard

## Operational Explanation

The International Load Line Certificate attests that the ship meets the minimum freeboard requirements calculated according to the International Convention on Load Lines (1966, as amended by the 1988 Protocol). Freeboard determines the maximum permissible draft, physically marked on the hull with the load line mark (Plimsoll mark).

The certificate concerns not only the numerical freeboard calculation but also the "conditions of assignment": height of door sills, hatch coamings, closing appliances for exposed ventilators and air pipes, freeing ports and scuppers, and crew protection guardrails — all elements checked at survey.

## Regulatory Reference

International Convention on Load Lines, 1966, as amended by the 1988 Protocol and further revised in 2003: requires an initial survey, a renewal survey and an annual survey to verify continued compliance with the freeboard conditions of assignment.

## Scope of Application

Every ship engaged on international voyages subject to the Load Line Convention, according to the applicable size and type thresholds.

## Procedure / How to Complete It

1. Verify the correct marking of the load line mark (Plimsoll mark) and the deck line on both sides of the ship amidships.
2. Verify the conditions of assignment: sill heights, closing appliances for hatches/ventilators/air pipes, freeing ports and guardrails.
3. Confirm that the operating draft never exceeds the assigned freeboard for the applicable season and navigation zone.
4. Conduct the annual survey verifying that no structural modification has altered the conditions on which the assigned freeboard is based.
5. Renew the certificate according to the HSSC five-year cycle, with a renewal survey that repeats the full verification of the conditions of assignment.

## Practical Example

Verification example: an annual survey confirming the integrity of hatch closing appliances and the absence of unauthorized structural modifications that could alter the assigned freeboard, with the Plimsoll mark verified legible and compliant on both sides.

## Real Cases

Cases of instability or progressive flooding in adverse weather conditions have in some instances been traced back to an operating draft exceeding the assigned freeboard, or to closing appliances (hatches, ventilators) not maintained per the original conditions of assignment, reducing the safety margin the certificate is theoretically meant to guarantee.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Operating draft exceeding the assigned freeboard for the zone/season | Direct violation of the Convention, reduction of the real safety margin | Always verify the draft against the assigned freeboard before every departure
Closing appliances for hatches/ventilators not maintained per the original conditions of assignment | The theoretical freeboard safety margin no longer matches the ship's actual condition | Include closing appliance checks in the routine maintenance program, not only ahead of survey
Structural modifications made without assessing their impact on the assigned freeboard | Certificate no longer representative of the ship's actual condition | Always assess the freeboard impact of any significant structural modification, involving the Classification Society

## PSC Observations

PSCOs check the legibility and correctness of the load line mark, consistency of the operating draft with the certificate, and the condition of the closing appliances covered by the conditions of assignment.

## Operational Tips

- Always check the operating draft against the assigned freeboard, not just against commercial cargo capacity.
- Include closing appliances (hatches, ventilators, air pipes) in the routine maintenance program, not only ahead of survey.
- Always involve the Classification Society before structural modifications that could alter the assigned freeboard.

## Checklist

- Load line mark and deck line correctly marked and legible
- Conditions of assignment (sills, closures, freeing ports, guardrails) verified
- Operating draft always within the assigned freeboard
- Annual survey conducted with no unverified structural modifications
- Impact of any structural modifications on freeboard assessed with the Class

## FAQ

What is the Plimsoll mark?
It is the load line mark, a circle 300 mm in outside diameter intersected by a horizontal line, marked amidships on both sides, indicating the maximum permissible draft according to the assigned freeboard.
Is the freeboard the same in every navigation zone?
No: different freeboards apply (summer, winter, tropical, fresh water), each marked separately on the hull according to the scheme set out in the Convention, depending on zone and season.
Does a minor structural modification always require a new freeboard assessment?
It depends on the nature of the modification: changes affecting buoyancy, the arrangement of watertight compartments, or the conditions of assignment require an assessment by the Classification Society to check the impact on the assigned freeboard.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

Tonnage Certificate and IMO Number Harmonized System of Survey and Certification (HSSC)

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