Shipping Out-of-Gauge (OOG) cargo on a Flat Rack is fundamentally different—and therefore priced differently—than shipping standard freight. When you move oversized machinery, industrial components, or heavy materials, you’re not just paying for ocean transit; you are paying for specialized handling, equipment, and vessel space.
Understanding the layered surcharges associated with flat racks is essential for accurate budgeting and avoiding unexpected expenses.
1. The Core Cost: Out-of-Gauge (OOG) Surcharges
The primary differentiator between standard freight and flat rack cargo is the Out-of-Gauge (OOG) Surcharge. This fee compensates the carrier for the space your cargo occupies beyond the dimensional perimeter of the flat rack itself.
- Calculation: The OOG surcharge is calculated based on the precise distance the cargo extends (or over-gauges) in each dimension: width, height, and length.
- Space Impact: OOG cargo often consumes the space of adjacent containers—sometimes two or three standard slots—on the vessel’s deck, which reduces the ship’s overall revenue-earning capacity. The OOG surcharge compensates the carrier for this lost space and the complexity of managing an asymmetrical load. The greater the over-gauge dimension, the higher the fee.
2. The Equipment Cost: Special Equipment Surcharge (S.E.S.)
Even if your cargo perfectly fits within the dimensions of the Flat Rack (which is rare but possible for very heavy, dense loads), a Special Equipment Surcharge (S.E.S.) will still apply.
- Why the S.E.S.?: Flat racks are specialized, limited, and expensive assets for the carrier. The S.E.S. covers the higher cost of procurement, maintenance, repositioning, and storage of this Special Equipment compared to ubiquitous standard dry containers.
- Non-Standard Flow: Since flat racks are not high-volume equipment, they require carriers to actively manage their movement and availability, adding a logistics cost passed on through this surcharge.
3. Port, Vessel, and Handling Fees
Flat racks cannot be handled by the automated, high-speed equipment used for standard containers. This necessitates specific, high-cost manual intervention at the terminal and aboard the vessel.
- Shore Handling (Lift) Fees: Flat rack cargo usually requires the use of specialized shore cranes or heavy-lift gear rather than standard yard gantry cranes. These “special lift” charges are significantly higher than standard terminal handling charges (THC).
- Vessel Stowage Planning: OOG cargo is almost always stowed on the top deck of the vessel for easier loading/unloading and to avoid structural interference below deck. This deck placement requires careful pre-planning and dedicated oversight by the vessel’s crew, leading to increased administrative and operational fees.
- Storage Fees: Due to their non-standard nature, flat racks often have little to no free time at the terminal and can incur storage fees quickly after arriving, especially if the subsequent vessel arrival is delayed.
Key Takeaway: To avoid costly financial surprises, shippers must obtain a detailed, all-inclusive quote based on the exact final dimensions of the secured cargo, not just the flat rack dimensions.
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