The moment cargo won’t fit inside a standard container, you have a choice to make — and it’s not one choice but a short decision tree. Flat rack, open top, breakbulk and RoRo each move out-of-gauge freight, but they suit different shapes, weights and pieces, and they price very differently. Picking the right one is where project ocean freight is won.
The four methods, and what each is for
Flat rack — a container base with no sides. For cargo that’s too wide or heavy for a standard box but still a manageable single piece: machinery, vehicles, structures. It keeps you inside the container system — standard cranes, cell handling — while carrying over-width and over-height loads by blocking the neighbouring slots.
Open top — standard footprint, removable tarpaulin roof. For cargo that’s tall or awkward to load through end doors but fits the container’s floor plan. The top comes off, the load drops in by crane, over-height protrudes under an OOG declaration.
Breakbulk — loaded piece by piece directly into the hold. For freight too big or heavy for even flat racks: large machinery, long structures, plant. Maximum flexibility, using ship or shore cranes — at the cost of containerized convenience.
RoRo — driven or towed on and off via a ramp. For self-propelled and rolling equipment: loaders, cranes, trailers, vehicles. It avoids the lift entirely, but sailings are route-specific, so it’s a lane question as much as a method.
How to choose
Work down these in order:
- Does it roll? If it’s self-propelled or on wheels, RoRo is often the lowest-risk, lowest-handling option — if a sailing serves your lane.
- Does it fit a flat rack’s footprint and weight? If it’s a single piece within reach of a flat rack (over-width/height handled by blocking), that usually keeps cost and handling down versus breakbulk.
- Is it tall but floor-plan-friendly, loaded from above? Open top.
- Is it bigger or heavier than any of those can take? Breakbulk, with a lift plan.
The deciding inputs are always the same: accurate dimensions and weight, per piece, including protrusions and the centre of gravity for heavy items.
How OOG prices — the space around the cargo
The surprise in out-of-gauge pricing: you pay for the space your cargo blocks, not just the space it fills. An over-width load on a flat rack sterilizes the slots beside it; an over-height load blocks stacking above. So a piece slightly over a threshold can cost far more than one just under it, because it spoils neighbouring capacity. This is why accurate over-dimensions early matter so much — they let the carrier plan stowage and quote the real footprint, not a guess.
Lashing is part of the shipment, not an afterthought
On flat racks, breakbulk and heavy lift, lashing and securing is engineered to the forces the load will see at sea — chains, straps, welded stoppers, blocking and dunnage. It’s a safety and acceptance requirement: inadequate securing is grounds for the carrier to refuse the load, and a piece that shifts in a hold endangers the whole vessel. Budget it and plan it in, don’t bolt it on at the terminal.
Where it connects
The ocean method you choose constrains the inland move on the other end — a breakbulk piece still has to get from port to site on a permitted heavy haul. Decide them together. Send us the piece and both ends and we’ll choose the method and quote the whole move.