Tools · sea routing

Ships don't travel in straight lines.

Shanghai to Felixstowe is 18,972 km of actual sailing — through Malacca, past Bab-el-Mandeb, up the Red Sea, through Suez, out at Gibraltar. The straight-line great circle is 9,176 km. Anyone quoting you transit off a point-to-point distance is out by a factor of two. This routes over real canal, strait and cape waypoints, and shows what happens when Suez closes.

Route a lane → All four tools Price the shipment
18,972
km CN→UK via Suez
2.07×
vs great circle
+6,182
km via the Cape
£0
To find out
The route · /api/searoute

Dijkstra over canal, strait and cape waypoints. Not over land.

Enter a UN/LOCODE (CNSHA), an ISO2 country code (CN) or raw coordinates as "lat,lng". Set the vessel draught and a canal too shallow for the vessel is excluded from the graph — which is how you find out you're on a Cape routing before the carrier tells you.

UN/LOCODE, ISO2 country, or "lat,lng". Check the resolved coordinates in the result.
Same formats. An unrecognised code falls back to an approximate position.
Drives transit time only. 16 kn is a typical container service speed; slow steaming runs lower.
Gates the canals. Too deep for Suez or Panama and the route is forced around the cape.

Indicative · a graph over canal/strait/cape waypoints, not a navigational chart · not for passage planning

The honest version

What this is — and what it isn't.

what it is

A routing graph, honestly built

A shortest-path search over a network of canal, strait and cape waypoints. It will never route you across a continent, and it names every waypoint it used so you can sanity-check the path yourself.

what it isn't

Not a navigational chart

It doesn't know weather routing, traffic separation schemes, seasonal ice limits, piracy exclusion zones or your carrier's actual port rotation. Do not use it for passage planning. Use it to sanity-check a distance and a transit claim.

why it matters

The Cape number is the risk number

Red Sea disruption turned the Cape diversion from a hypothetical into a live routing for a lot of Asia–Europe traffic. When your route uses a canal, the tool always shows the alternative distance and transit so you can price the downside before it happens.

the assumption

Transit is distance ÷ speed

Pure sailing time at the speed you enter. No port calls, no waiting for a berth, no canal queue, no bunkering. Real port-to-port transit is longer — treat this as the floor, not the schedule.

FAQ

Why is the routed distance so much bigger than the great circle?
Because a great circle is the shortest path over a sphere and takes no account of land. From China to the UK it runs straight over Asia and Europe. The real route has to reach the sea corridors that exist — Malacca, Bab-el-Mandeb, Suez, Gibraltar — which on that lane is 2.07 times the straight-line figure.
What does the detour ratio tell me?
Routed distance divided by great-circle distance. Close to 1 means the lane is nearly direct. Above 2 means most of the voyage is being spent getting to and through chokepoints, which is also a signal of how exposed the lane is to a single closure.
What happens if I set a deep draught?
Canals shallower than the vessel are dropped from the graph, so the search finds the next best path — usually around the Cape of Good Hope. That's a useful check for larger tonnage before anyone quotes you a Suez transit time.
Where do the CO₂ and freight numbers live?
Not here — this tool answers distance and transit only. For freight cost across road, sea and air with landed cost, duty and an indicative CO₂ figure, use the instant quote.
Indicative routing, not a navigational chart. Not for passage planning.