A TEU is a twenty-foot equivalent unit — the standard container the global trade system is denominated in. A 40-foot container is two TEU. A modern Ultra-Large Container Vessel (ULCV) like the MSC Tessa carries up to 24,346 TEU — that's enough to fill a freight train roughly 100 miles long.

Container shipping moves about 90% of non-bulk world trade by volume. The system works because the box is the unit: same dimensions, same lifts, same train cars and chassis, same crane sequence at every major port.

A vessel's class is mostly defined by which chokepoints it can pass:

Feeder (~3,000 TEU) — anywhere. The intra-regional workhorse. Panamax (~5,000 TEU) — fits the old Panama locks (32.31m beam, 12.04m draft). Neo-Panamax (~15,000 TEU) — fits the 2016 Panama new locks (49m beam, 15.2m draft). ULCV (~24,000 TEU) — too wide for Panama; only the Asia–Europe Suez/Cape lane and inter-hub trans-Pacific calls work for these.

For tankers, the analogues are Aframax → Suezmax → VLCC → ULCC, gated by Suez Canal draft and Strait of Hormuz traffic.

About 11% of global trade passes through the Bab-el-Mandeb / Suez corridor. When it disrupts (Houthi attacks since Nov 2023), the alternative is the Cape of Good Hope — adding 10–14 days and ~30% more bunker fuel per voyage. Multiply that by the 400-odd liner vessels that touch the lane each month and the bill is real.

Panama is the other major squeeze point. ~70% of the canal's traffic touches the US, so when the 2023–24 drought forced ACP to cut transits, premium-slot auctions hit $4M and shippers paid for it.

Insurance war-risk premium for vessels transiting the Red Sea has stayed in the 0.6–1.0% of hull value range since the diversions began — a 100× multiplier on the baseline.

Eleven three-letter codes published by the International Chamber of Commerce that decide who pays for what, who insures what, and where the legal handoff happens between seller and buyer.

FOB (Free On Board): seller delivers to the vessel at the port of origin, buyer takes risk + cost from then. CIF (Cost, Insurance, Freight): seller pays freight + insurance to the destination port; risk still passes at origin. DDP (Delivered Duty Paid): seller handles everything to the buyer's door, including import duty. The current revision is Incoterms 2020.

Fuel is the biggest variable cost in deep-sea shipping. At design service speed (~22 knots for a modern ULCV), fuel burn is roughly cubic in speed — drop two knots and you save ~30% of fuel. The industry has been slow-steaming since ~2008, partly for cost, partly to absorb excess fleet capacity, partly to cut CO₂.

VLSFO (very low sulphur fuel oil, the IMO 2020 standard) trades in the $500–600/tonne range at Singapore. A ULCV burns ~200 tonnes/day at service speed — so a Shanghai-Rotterdam round trip is on the order of $1.5–2M in fuel alone.

Container freight rates have three main public benchmarks: Drewry WCI (weekly, 8 lanes), SCFI (weekly, Shanghai outbound), FBX (daily, by Freightos). Carriers add fuel surcharges (BAF), war-risk surcharges, and peak-season surcharges on top. Spot rates can move 5× through a cycle.

For a 40' container from Shanghai to Rotterdam in 2025, post-Red-Sea diversion: roughly $3,400 spot. Add $200–400 in surcharges. Add customs (a few hundred), inland drayage (~$300–800 depending on distance to the inland point), and demurrage if you don't pick the container up within free days.

Every commercial vessel of >300 gross tonnage broadcasts AIS (Automatic Identification System) — VHF position reports including MMSI, position, course, speed, vessel type, destination, ETA. Coastal stations and satellite constellations (Spire, exactEarth, ORBCOMM) pick them up; aggregators like MarineTraffic and Vesselfinder make them visible on the web.

AIS is the data feed behind virtually every "what's happening to my container" tool. It's also how you can tell at a glance that a port is congested (lots of vessels at anchor) or that a vessel is doing a sketchy ship-to-ship transfer in the South China Sea.

From the chart in the disruption timeline above: geopolitical events (Houthi attacks, Russia-Ukraine, Iran-Israel), climate events (Panama drought, Indus floods), infrastructure failures (Ever Given grounding, Baltimore Key Bridge collapse), industrial action (Felixstowe / longshoremen strikes), and regulatory shifts (IMO 2020 sulphur cap, IMO 2030 carbon intensity).

The pattern: lanes that look bombproof on a clear day prove fragile when one node fails. The whole point of munshi is to make that fragility legible — chokepoints, alternatives, the cost of each detour.