Lashing Software and Loading Computers

Lashing software is the onboard or shore-side program that computes the forces on a container securing arrangement for a proposed stow and confirms that they remain within the limits of the Cargo Securing Manual. On a modern container ship it has largely replaced the printed motion limits that older manuals gave the master directly.

That substitution created a gap that casualty investigations have repeatedly identified. Where a manual once stated roll and pitch angles beyond which lashings could fail, the modern arrangement supplies acceleration limits and relies on a calculation the bridge cannot audit. The United Kingdom investigation into the CMA CGM G. Washington container loss found that pitch and roll limits were not readily available from the ship’s loading computer, and that the master substituted his own judgement.

IACS Unified Requirements C6 on lashing software and C7 on the approval and certification of container securing systems apply to container ships contracted for construction on or after 1 July 2025, and harmonise what had been society-specific practice.

Scope boundary: the statutory cargo securing framework and the lashing force calculation method are covered in the marine cargo securing and lashing systems article. This article covers the software, its approval and its interface with the bridge.

The full article will cover the calculation the software performs, the approval regime, the interface with the loading computer and the stability calculation, the transparency problem, and the recommendations that produced the IACS requirements.