Operational Guide · Registers & Logbooks

# Damage Stability of Ro-Ro Passenger Ships (SOLAS 2020)

Born from the Estonia disaster in 1994, the discipline governing the stability of Ro-Ro passenger ships is far stricter today than it was thirty years ago: since 2020 the SOLAS standard has absorbed and surpassed the earlier Stockholm Agreement.

SOLAS 2020 damage stability Ro-Ro passenger ships Stockholm Agreement

## Operational Explanation

Following the MV Estonia disaster (September 1994), eight Northern European countries agreed in Stockholm in 1996 on a stricter damage stability standard for Ro-Ro passenger ships, known as the Stockholm Agreement, initially applied only in North European waters.

The SOLAS 2020 amendments to Chapter II-1 extended a comparable level of protection globally, significantly increasing the required subdivision index (R) and recalculating the survival factor (s-factor) for flooding scenarios involving vehicle spaces and large open spaces typical of Ro-Ro passenger ships. These requirements apply to ships with keel laid from 1° January 2020.

## Regulatory Reference

SOLAS Chapter II-1, SOLAS 2020 amendments: increase in the required subdivision index (R) and recalculation of the survival factor (s-factor) for flooding scenarios in the vehicle spaces/large open spaces of Ro-Ro passenger ships, applicable to ships with keel laid from 1° January 2020, at a global standard level comparable to the 1996 Stockholm Agreement.

## Scope of Application

Ro-Ro passenger ships with keel laid from 1° January 2020; existing ships remain subject to the damage stability regime applicable at the time of their construction, unless substantial structural modifications are made.

## Procedure / How to Complete It

1. Verify the ship's keel-laying date to determine the applicable damage stability regime (pre-2020, Stockholm Agreement if in European waters, or SOLAS 2020).
2. Keep the damage stability documentation on board, consistent with the regime applicable to the ship.
3. Integrate the operational limits arising from the stability calculation (for example load limits on vehicle decks) into daily operating procedures.
4. In the event of structural modifications that alter the internal subdivision or vehicle spaces, verify the impact on the damage stability calculation.
5. Train deck officers on reading and practically applying the operational limits arising from their specific ship's stability calculation.

## Practical Example

Example: the cargo officer of a Ro-Ro passenger ship with keel laid in 2021 verifies, before every departure, that the load distribution on the vehicle deck complies with the operational limits arising from the SOLAS 2020 damage stability calculation, distinct from those that would apply to a sister ship with keel laid before 2020.

## Real Cases

The MV Estonia disaster, in which the loss of the bow visor caused rapid flooding of the vehicle deck and the sinking of the ship with the loss of more than 850 lives, remains the reference case that motivated both the 1996 Stockholm Agreement and, more than two decades later, the global raising of the standard with SOLAS 2020.

## Common Mistakes Mistake Library

Mistake | Consequence | How to avoid it
--- | --- | ---
Applying the operational load limits of a sister ship with a different keel-laying date, assuming the stability regime is identical | Exceeding the specific ship's real operational limits, with a reduced damage stability safety margin | Always verify the applicable stability regime based on your own ship's specific keel-laying date, not that of a sister ship
Structural modifications to vehicle spaces not followed by a reassessment of the damage stability calculation | Stability documentation no longer representative of the ship's actual configuration | Always reassess the stability calculation in the event of structural modifications that alter the subdivision or vehicle spaces

## PSC Observations

PSCOs may check the consistency between the damage stability documentation on board, the regime applicable based on the ship's keel-laying date, and the operational limits actually observed in load distribution.

## Operational Tips

- Know your ship's exact keel-laying date: it determines which damage stability regime applies, not the delivery or entry-into-service date.
- Do not assume a sister ship automatically shares the same stability regime: always verify the specific keel-laying date.
- Coordinate every structural modification to vehicle spaces with a reassessment of the damage stability calculation.

## Checklist

- Ship's keel-laying date verified to determine the applicable stability regime
- Damage stability documentation on board and consistent with the applicable regime
- Load operational limits on vehicle decks observed in daily practice
- Deck officers trained on the ship's specific operational limits
- Reassessment conducted in the event of structural modifications to vehicle spaces

## FAQ

What is the Stockholm Agreement?
A stricter damage stability standard for Ro-Ro passenger ships, agreed in 1996 by eight Northern European countries after the Estonia disaster, initially applied only in North European waters.
What changes with SOLAS 2020 compared with the Stockholm Agreement?
SOLAS 2020 extends a comparable level of protection globally, increasing the required subdivision index (R) and recalculating the survival factor (s-factor), for ships with keel laid from 1 January 2020.
Do existing Ro-Ro passenger ships need to comply with SOLAS 2020?
No, the SOLAS 2020 regime applies to ships with keel laid from 1 January 2020; existing ships remain subject to the regime applicable at the time of their construction, unless substantial structural modifications are made.
🎬 Additional photos, videos and interactive diagrams for this topic will be available in a future version of the platform.

## Related Topics

Ro-Ro and Vehicle Spaces: New Fire Detection and Protection Requirements (2026)Safe Return to Port

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