Glossary
Strait of Hormuz crisis terms.
Plain-language definitions of the shipping, oil-market, naval, and insurance terms used across Straits coverage. If a term you need is missing, tell us.
- ADCOP
Abu Dhabi Crude Oil Pipeline. Carries up to 1.5 million bpd from UAE oilfields to Fujairah on the Indian Ocean side, bypassing the Strait of Hormuz. The smaller of the two operational bypass routes (Saudi Petroline being the larger).
- AIS
Automatic Identification System. A VHF-based broadcast standard required on most large commercial vessels, providing position, course, speed, and identity. Straits reads live AIS data from AISStream.io as a presence overlay; the headline daily transit count comes from IMF PortWatch, which itself derives from a global AIS network.
- AIS gap (going dark)
A vessel that was actively broadcasting on AIS and has stopped transmitting. Causes are ambiguous: equipment failure, GPS spoofing, deliberate evasion, or simply leaving the bbox can all produce the same observation. The homepage block applies a strict filter (tanker, ≥50 prior sightings, last position inside the core area, last seen 3–24 hours ago) to bias toward false-negatives.
- bbl
Barrel of oil; 42 US gallons or about 159 liters. The standard unit for crude oil pricing.
- bpd
Barrels per day. The Strait of Hormuz carries roughly 17 million bpd of crude under normal conditions, about 21% of world seaborne oil trade.
- Brent
Brent crude. A light, sweet crude oil benchmark priced from production in the North Sea (the original Brent field plus surrounding fields). The reference price for roughly two-thirds of internationally traded crude.
- Bunker fuel
The heavy fuel oil that powers commercial shipping. Cape-of-Good-Hope reroutes burn proportionally more bunker than Hormuz-and-Suez routings, which is why container surcharges quoted in dollars per TEU rise even when crude prices are flat.
- Cape of Good Hope reroute
Routing Asia-Europe shipping south of Africa rather than through the Suez Canal and Strait of Hormuz. Adds roughly 14 days per leg and burns proportionally more fuel.
See the full explainer at /cape-of-good-hope-reroute.
- CENTCOM
United States Central Command. The unified combatant command responsible for US military operations in the Middle East, including the Persian Gulf and Strait of Hormuz.
- Chokepoint
A narrow shipping passage whose closure or disruption has outsized effects on global trade. The Strait of Hormuz, the Suez Canal, and the Strait of Malacca are the three most economically significant.
- Convoy escort
Naval vessels accompanying commercial ships through a high-threat area. Project Freedom, launched by the US in May 2026, is the multilateral convoy regime escorting traffic through the strait under US, UK, and French naval cover.
- Cushing
Cushing, Oklahoma: the WTI delivery hub and the storage benchmark referenced in WTI futures contracts. Inventory swings here track the North-American crude balance independent of the Gulf-Coast / SPR picture; pairs with the Brent–WTI spread to indicate whether disruption is global or American-specific.
- DWT
Deadweight tonnage. The total weight a vessel can safely carry, including cargo, fuel, ballast, crew, and provisions. Used as a normalized measure of shipping capacity.
- EIA
US Energy Information Administration. The statistical agency of the US Department of Energy. Publishes the daily spot prices, weekly petroleum status reports, and chokepoint reference figures Straits cites.
eia.gov
- GDELT
Global Database of Events, Language, and Tone. An open-source machine-coded record of events surfaced from news media worldwide; used for indexing war events when the feed is online and within rate limits.
- Goreh-Jask
Iran's pipeline carrying crude from Goreh to the port of Jask on the Indian Ocean, bypassing the Strait of Hormuz. Nameplate capacity ~0.35 million bpd; currently operating at a fraction of that.
- IMO
In Straits, refers to the International Maritime Organization's seven-digit ship-identification number, which (unlike MMSI) does not change when a vessel is renamed or reflagged. The OFAC × AIS join uses IMO when available because it survives shadow-fleet name changes.
- IMF PortWatch
A free, IMF-attributed dataset publishing daily transit counts for global maritime chokepoints, including the Strait of Hormuz (chokepoint6). Built on global AIS signals from ~90,000 ships via the IMF / Oxford / UN Global Pulse partnership. Straits uses PortWatch as the headline daily transit count: it is methodologically transparent, citable, and survives any AISStream outage. Updates are batched weekly on Tuesdays.
- IRGC
Islamic Revolutionary Guard Corps. The branch of Iran's armed forces controlling the maritime forces operating in the Persian Gulf, including the small fast-attack craft involved in the 2026 closure.
- JWC
Joint War Committee at Lloyd's. Sets the listed-area pricing zones for marine war-risk insurance. When the Strait of Hormuz is JWC-listed, war-risk premiums spike and many operators stop calling the area without naval escort.
- LNG
Liquefied Natural Gas. Roughly a quarter of global LNG trade flows through the Strait of Hormuz, predominantly Qatari production bound for Asia and Europe. LNG carriers cannot easily reroute and are highly dependent on Hormuz transit.
See the full explainer at /lng-supply-at-risk.
- MMSI
Maritime Mobile Service Identity. A nine-digit number that uniquely identifies a vessel for AIS broadcasts and radio communication. Unlike IMO, MMSI can be reassigned when a vessel is sold or reflagged.
- OFAC SDN
US Treasury Office of Foreign Assets Control, Specially Designated Nationals list. The canonical US sanctions list including ~1,500 sanctioned vessels. Straits joins the SDN against AISStream live positions to surface OFAC-listed vessels currently in the strait window.
treasury.gov/ofac
- OPEC+
Organization of the Petroleum Exporting Countries plus aligned producers (Russia, Mexico, Kazakhstan, others). Sets coordinated production quotas that influence Hormuz flow volume independent of geopolitical disruption.
- Persian Gulf / Arabian Gulf
The same body of water, with naming convention reflecting national perspective. Straits uses "Persian Gulf" in line with US Board on Geographic Names usage; readers should expect either term in source-press citations.
- Petroline
Saudi Aramco's East-West Pipeline carrying Arabian Light crude from Abqaiq to Yanbu on the Red Sea. Capacity 5 million bpd; the single largest non-Hormuz route for Gulf crude.
- Sanctioned vessel / Shadow fleet
Tankers operating under sanctions, typically through a shifting set of shell-company owners, frequent renames, and AIS irregularities. The "shadow fleet" is the trade-press shorthand for vessels that primarily carry sanctioned crude (Iranian, Russian, Venezuelan) into global markets via off-the-books transactions.
- Spot price
The price for immediate (typically next-day) delivery of a commodity, as opposed to a futures contract for delivery on a specified future date. Brent and WTI spot prices are the canonical references for crude.
- SPR
Strategic Petroleum Reserve. The US emergency stockpile held in salt caverns at four sites along the Gulf Coast. Straits tracks the rolling weekly draw from EIA's Weekly Petroleum Status Report; non-US holders (China, Japan, South Korea, EU, India) are tracked as editorial best-estimates.
See the full explainer at /strategic-petroleum-reserves.
- Stranded vessel
A vessel anchored or stopped (rather than transiting) inside the strait window. Stranded count = anchored + stopped, refreshed every 30 minutes from AIS, with hourly buckets going back 7 days on the front-page sparkline.
- Suez Canal
The Egyptian canal connecting the Red Sea and the Mediterranean. Combined with the Strait of Hormuz, it is the operational pair for Gulf-to-Europe crude routing; Cape-of-Good-Hope reroutes bypass both.
- TEU
Twenty-foot Equivalent Unit. The standard measure of container shipping capacity. A 40-foot container is two TEUs. Surcharges on Cape-rerouted services are typically quoted in dollars per TEU.
- Throughput
Straits expresses throughput as the IMF PortWatch daily transit count divided by the pre-2026-02-28 PortWatch median (~94/day), rendered as a percentage. 100% means the strait is functioning at peacetime volumes; 0% means transits have effectively halted. The pre-crisis anchor is deliberate: a rolling baseline would collapse during a sustained closure and silently re-flag the dashboard as 'open.'
- VLCC
Very Large Crude Carrier. A tanker class carrying about 2 million barrels of crude per voyage. The workhorse of Gulf-to-Asia oil trade and the unit of measure for war-risk premium quotes.
- WTI
West Texas Intermediate. The US light, sweet crude oil benchmark, priced at Cushing, Oklahoma. Tends to trade at a discount to Brent, with the spread reflecting global versus North American supply-demand.