What Is General Average, and Why Might Cargo Owners Have to Post Security?

A container arrives at port, undamaged, exactly as it left the factory — and the consignee is still told it can't be released until a security deposit is posted. For anyone unfamiliar with General Average, that can sound like a mistake or a shakedown. It's neither. It's the operation of one of the oldest continuously applied principles in commercial law, one that predates modern shipping by centuries and still governs how loss is shared when an entire voyage is put at risk.

Understanding why an undamaged shipment can still be caught up in a General Average case — and what a cargo owner is actually expected to do about it — starts with understanding what the principle is actually protecting against.

What General Average Means

General Average is a principle of maritime law under which a loss deliberately and reasonably incurred to save a vessel and its cargo from a common peril is shared proportionally among everyone who had a financial interest in the voyage — the shipowner and every cargo owner aboard — rather than falling entirely on whoever suffered the direct loss. The core requirement is that the sacrifice or expense must be deliberate and made for the common safety, not accidental damage from the peril itself.

A classic example is jettisoning some cargo overboard to lighten a vessel in danger of sinking: the cargo that's sacrificed is a real loss, but because that sacrifice was made to save the ship and the rest of the cargo together, everyone who benefited from the ship and cargo being saved shares in compensating for it — not just the owner of the goods that were thrown overboard. The same logic extends to extraordinary expenses incurred for common safety, such as towage or salvage costs after a grounding, even when no cargo is physically sacrificed at all.

How a General Average Event Gets Declared

A General Average case begins with an event that puts the entire voyage — vessel and cargo together — at risk from a common peril: a fire on board, a grounding, severe heavy-weather damage, or a mechanical failure that leaves the vessel unable to complete its voyage safely without extraordinary intervention. It's the shipowner, generally acting through the vessel's master and the shipowner's managers, who formally declares General Average once the situation meets the legal criteria for it.

Declaring General Average sets the adjustment process in motion. The shipowner typically appoints an independent average adjuster — a specialist firm with no financial interest in the outcome — to investigate the circumstances, confirm that the loss genuinely qualifies as General Average rather than an ordinary casualty, and begin the work of quantifying it. This declaration and the appointment of an adjuster usually happen fairly early relative to the overall process, but the adjustment itself, given its complexity, can take considerably longer to finalize.

Why Cargo Owners Post Security Even When Undamaged

Once General Average is declared, the shipowner has a legal right to withhold delivery of cargo until each cargo owner secures payment of its eventual contribution — and this applies to every cargo owner aboard, regardless of whether their specific goods were the ones sacrificed or damaged. The reasoning is that the shipowner (and the other contributing parties) shouldn't have to release cargo and lose their leverage to collect a contribution before the amount owed is even known.

Because the full adjustment calculation can take a long time — sometimes many months — to complete, requiring the shipowner to wait for final numbers before releasing any cargo at all would leave every cargo owner's goods stuck in limbo indefinitely. Security solves that: once posted, the shipowner has assurance that the contribution will eventually be paid, so the cargo can be released promptly while the detailed calculation proceeds in the background. That security is typically set at a level based on a preliminary estimate of what the ultimate contribution is likely to be, and it's returned or adjusted once the final adjustment is complete.

This can feel counterintuitive to a cargo owner receiving a security request for goods that traveled the entire voyage without a scratch, but it reflects a basic feature of how the risk-sharing works: the value of an undamaged cargo owner's goods is exactly what makes them a contributing beneficiary of the sacrifice in the first place. If the vessel had been lost entirely, that cargo owner's goods would have been lost too — the sacrifice that was made is, in effect, what allowed those undamaged goods to complete the voyage at all, which is the underlying logic that obligates a proportional contribution.

The General Average Adjustment Process

The average adjuster's core job is to establish two numbers: the total amount of General Average loss (the value of what was sacrificed, plus any extraordinary expense incurred for common safety), and the total value of the interests that benefited from that sacrifice — the vessel, the cargo aboard, and freight, valued as of the time and place the voyage effectively ended or the danger was resolved. Each contributing interest's share of the total loss is then calculated in proportion to its value relative to that combined total.

This process is often internationally standardized in practice through a widely used set of rules — commonly known as the York-Antwerp Rules — which many bills of lading incorporate by reference to give shipowners, cargo owners, and adjusters a common, well-established framework for how General Average is calculated, even when the parties involved are based in different countries with different domestic laws. Because the adjustment involves detailed valuation work across every cargo interest on the voyage, not just the interests directly affected by the sacrifice, it's a genuinely lengthy technical exercise, and cargo owners are usually kept informed through periodic updates from the adjuster or from their cargo insurer rather than being involved in the calculation directly.

How Cargo Insurance Interacts with General Average

Whether or not a cargo owner has cargo insurance changes what posting security actually involves in practice. Most standard cargo insurance policies that cover General Average will allow the insurer to issue a General Average bond directly to the shipowner, standing in for a cash deposit — the cargo owner typically just needs to notify their insurer promptly that a General Average situation has arisen and provide the shipment documentation the insurer needs to issue that bond.

Without applicable insurance, a cargo owner generally needs to arrange a cash deposit or an independent bond themselves, and correspond directly with the average adjuster through to the final settlement, which can tie up working capital for the duration of what's often a lengthy adjustment process. This is one of the more concrete, practical reasons cargo insurance has value even for cargo that's never physically damaged: General Average exposure exists purely because of being aboard the same vessel as an incident, entirely independent of anything happening to the specific goods being insured.

What to Do If Your Shipment Is Involved in a General Average

If a shipment gets caught up in a General Average case, the first practical step is checking whether cargo insurance is in place and, if so, notifying the insurer immediately with the shipment's documentation — bill of lading, commercial invoice, and any correspondence already received about the case — so the insurer can begin arranging the bond. Acting promptly matters because the bond and release process, while faster than arranging a cash deposit from scratch, still takes some coordination time.

If insurance isn't in place, it's worth engaging a forwarder or a maritime claims specialist early to understand what security will be required and how it's calculated, rather than waiting until cargo is already held at destination to start that conversation. Throughout the process, keeping records of all correspondence from the shipowner, the average adjuster, and any insurer involved is useful, since the adjustment can take a long time to finalize and questions about the eventual contribution amount may come up well after the cargo itself has already been released.