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Ship Draft by Vessel Type: How Deep Different Ships Sit in the Water

A fully loaded Valemax bulk carrier draws 23 metres. That is deep enough that its keel would scrape the roof of a six-storey building if you stood the hull on end. A cruise ship three times its height above water draws only 9 metres. Why? Because draft is not about ship size. It is about what the ship does. Different trades, different drafts.

Why Vessel Draft Varies by Type

Cargo density is the biggest factor. Iron ore weighs about 2.5 tonnes per cubic metre. A bulk carrier filled with ore sits deep because the cargo is heavy relative to its volume. Crude oil is lighter at about 0.85 t/m3, but tankers carry enormous volumes so the total weight still adds up. LNG is light at 0.45 t/m3, and its carriers sit surprisingly shallow for their size. Containers are somewhere in the middle: the average container cargo density works out to roughly 0.6 to 0.8 t/m3 depending on what is inside those boxes.

Trade routes impose a hard ceiling. A ship built to call at shallow-water ports in Southeast Asia must have a shallower draft than one built for deep-water terminals in northwest Europe. Ships that transit canals are built to fit exactly within canal draft limits. A Panamax container ship exists because the old Panama Canal locks could handle 12.04 metres of draft and no more. A Suezmax tanker is designed around the 20.1-metre Suez Canal limit. Naval architects work backwards from these route constraints when they lay out the hull.

Speed requirements push draft in both directions. A deeper hull creates more wetted surface area, which means more frictional resistance and higher fuel consumption. Container ships, which run at 18 to 24 knots, need efficient hulls. Making them too deep would burn more fuel for the same speed. But go too shallow and the hull form becomes fat and blunt, creating wave-making resistance. Every vessel type has a sweet spot where draft balances speed against efficiency.

Stability provides the counterbalance. Wide-beam ships like cruise vessels and some container ships can be shallower because their breadth provides the righting moment that a narrow hull would need extra draft to achieve. A narrow tanker needs more draft to keep its centre of gravity low enough for stability, especially when carrying free-surface liquids that slosh around.

Canal constraints have literally shaped entire classes of ships. The Panama Canal created the Panamax standard and later the Neopanamax standard. The Suez Canal created the Suezmax. The Saint Lawrence Seaway created the Seawaymax. Each of these canal-defined ship classes was designed to squeeze the maximum cargo capacity out of a hull that just barely fits through the waterway. Draft is always the binding constraint because you cannot dig a ship deeper into the water the way you can widen a lock or lengthen a chamber.

Container Ships (8-17m Draft)

This matters for ports. If container ship draft had kept pace with capacity growth, today's largest box ships would draw 30 metres or more, and almost no commercial port on Earth could handle them.

Data sources: DNV class register, VesselFinder AIS data, shipbuilders' published specifications. Verified July 2026.

MSC Irina, at 24,346 TEU capacity, has a design draft of 16.5 metres and a structural (maximum) draft of 17.0 metres. In practice it typically operates at 14 to 16.4 metres, loading to full structural draft only on the deepest port calls. Emma Maersk, one of the pioneering Suezmax container ships delivered in 2006, draws 15.5 metres at design draft with a capacity of roughly 14,770 to 15,500 TEU (depending on whether Maersk's weight-based method or the standard slot-count method is used). In twenty years the maximum container ship draft has moved from about 15.5 metres to 17.0 metres, just 1.5 metres of additional depth while capacity nearly doubled from roughly 15,000 to 24,346 TEU.

The Neopanamax class deserves special mention. The expanded Panama Canal locks opened in 2016 with a maximum draft of 15.24 metres (50 feet) in tropical fresh water. Ships in this class, like COSCO Development at 13,092 TEU, were built to squeeze through those new locks with centimetres to spare. But drought in Panama's Gatun Lake during 2022 through 2024 forced the Panama Canal Authority to reduce allowable draft to as low as 13.56 metres at times. Laden Neopanamax ships drawing 15 metres could not transit at full load. Shippers either offloaded cargo for rail transport across Panama or rerouted around South America via the Strait of Magellan, a detour that adds 12 days and roughly $500,000 in fuel to a single voyage.

Our pillar guide to ship draft covers the underlying principles. For container capacity measurement, see our TEU glossary entry.

Bulk Carriers (10-23m Draft)

Grain loads at roughly 0.8 tonnes per cubic metre. Iron ore loads at roughly 2.5 tonnes per cubic metre, three times as dense. A Handymax bulker filled with grain might draw 11 metres. The same ship filled with iron ore would draw close to 14 metres, but it would run out of volume first: the cargo holds would be less than half full by volume before the ship reached its maximum draft. This is called "heavy cargo" loading, where draft limits cargo intake rather than hold capacity. For light cargoes like grain or wood chips, the holds fill up before the ship reaches its draft limit. The ship sails with empty space but maximum volume used.

Data sources: PIANC harbour design guidelines, IACS classification data, shipbuilders' published specifications. Verified July 2026.

The Capesize class gets its name from the route they must take. At 14.5 to 18.5 metres of loaded draft, these ships are too deep for both the Suez Canal and the Panama Canal. They round the Cape of Good Hope at the southern tip of Africa or Cape Horn at the southern tip of South America. A typical iron ore voyage from Brazil to China on a Capesize takes about 35 to 40 days. The extra distance compared to a canal transit adds roughly 7 to 10 days compared to what a Suezmax or Panamax ship would take. But the economies of scale more than compensate: a Capesize carries 180,000 tonnes of ore per voyage versus 80,000 for a Panamax bulker.

The Kamsarmax is a regional subclass named after the bauxite loading terminal at Kamsar, Guinea. The primary design constraint is a maximum length overall of about 229 metres (the port's length limit), with a typical summer loaded draft of about 14.0 to 14.5 metres. These ships carry roughly 80,000 to 82,500 DWT. The Newcastlemax was designed to fit the coal loading terminals at Newcastle, Australia, with a maximum length of 300 metres, beam of 50 metres, and draft of about 18 metres at roughly 210,000 DWT.

The Valemax class, led by Vale Brasil delivered in 2011, operates at the extreme end. These 400,000 DWT ships (402,347 DWT for the lead vessel) draw 23 metres fully loaded. They can only call at a handful of purpose-built deep-water terminals: Ponta da Madeira in Brazil (Vale's own terminal), Rotterdam Europort in the Netherlands, Sohar in Oman, Teluk Rubiah in Malaysia, and Subic Bay in the Philippines. When a Valemax loads at Ponta da Madeira, it takes on roughly 390,000 tonnes of iron ore in about 35 hours. At 23 metres draft, the under-keel clearance leaving the terminal channel is a carefully calculated margin measured in metres, not tens of metres.

For the full procedure on how draft translates to cargo weight, see our draft survey calculation guide.

Oil Tankers and LNG Carriers (12-24.5m Draft)

Data sources: DNV GL register, Euronav published specifications, Suez Canal Authority navigation rules. Verified July 2026.

LNG carriers are a surprise. A Q-Flex LNG carrier at roughly 107,000 tonnes deadweight and roughly 315 metres length draws only 12 metres. That is about the same draft as a Panamax container ship half its length, but the LNG carrier is carrying a far more valuable and technically complex cargo in membrane containment tanks (GTT Mark III or NO96 design, not Moss-type spherical tanks which are used on smaller conventional LNG carriers up to about 180,000 m3). LNG is light at 0.45 tonnes per cubic metre, so even fully loaded, the ship does not push deep. The prominent spherical tanks visible above deck on many conventional LNG carriers are Moss-type tanks filled with gas at minus 162 degrees Celsius, and the cargo weight is a fraction of what the hull volume would suggest.

The Seawise Giant, the largest ship ever constructed, was a ULCC supertanker measuring 458.45 metres in length with a laden draft of 24.6 metres. Built in 1979 as the Seawise Giant, later renamed Happy Giant, Jahre Viking, and finally Knock Nevis, it served through multiple roles: crude oil transport, oil storage during the Iran-Iraq War (where it was hit and sunk by Iraqi missiles in 1988, then raised and repaired), and finally as a stationary floating storage and offloading unit (FSO) off Qatar. It was scrapped at Alang, India, in 2010. At 24.6 metres of draft fully loaded, roughly 83% of its hull depth was submerged. It could not enter the English Channel, the Suez Canal, or the Panama Canal. It offloaded at offshore single-point moorings and lightering zones rather than entering harbours.

Today the TI-class supertankers (TI Europe, TI Oceania, TI Asia, TI Africa) are the largest operating tanker hulls by displacement. Built in 2002-2003 by Daewoo Shipbuilding, they displace approximately 441,500 DWT with a laden draft of approximately 24.5 metres. That is nearly as deep as the Seawise Giant. They currently operate as floating storage and offloading units (FSOs) off Malaysia and Qatar, not as active trading tankers. Their deep draft makes them impractical for most crude oil routes except dedicated deep-water terminal pairs. The operational VLCC fleet, the workhorse of the Middle East to Asia crude trade, typically draws 19 to 21 metres loaded and can access most major crude terminals in the Arabian Gulf, Singapore, and Northeast Asia.

Our load line and Plimsoll line guide explains the regulatory markings that set the maximum legal draft for tankers and all other commercial vessels.

Cruise Ships (8-10m Draft)

Data sources: Royal Caribbean International published specifications, Meyer Turku shipyard data, Cunard Line specifications. Verified July 2026.

How does a 250,800 GT ship that stands taller than a 20-storey building not tip over with only 9.25 metres of hull in the water? The answer is beam. An Icon-class ship has a waterline beam of 48.47 metres. That is more than five times its draft. The wide waterplane area provides enormous righting moment. The centre of buoyancy shifts far outboard when the ship heels even slightly, generating a strong restoring force. This is basic naval architecture: stability comes from waterplane area, not draft. A wide, shallow hull can be just as stable as a narrow, deep one.

The commercial logic is even more important than the engineering. Cruise lines sell itineraries, not cargo capacity. An Oasis-class ship generates revenue from onboard spending, ticket prices, and shore excursions. It does not earn money per tonne of cargo. Every metre of draft eliminated means access to additional ports. The 9.3-metre draft of Oasis of the Seas was deliberately chosen so the ship could dock at the major Caribbean cruise terminals, Nassau, Cozumel, St. Thomas, St. Maarten,without needing deep-water channels. A 12-metre draft would have cut the available Caribbean ports roughly in half. That is not a trade-off any cruise line's revenue department would accept.

The Queen Mary 2 at 10.0 metres is the exception, and it is an exception by design. She is not a cruise ship. She is an ocean liner, purpose-built for the North Atlantic run between Southampton and New York. She is the only active purpose-built ocean liner in service. Her deeper draft provides better seakeeping in winter North Atlantic conditions. Her reinforced hull can handle waves that would send a typical cruise ship running for shelter. The deeper draft is not a compromise; it is the reason the ship exists. She was built to do something cruise ships cannot do: maintain schedule through Force 10 storms in the North Atlantic in January.

For more on how draft relates to ship design, see our ship measurements guide.

Naval and Special Purpose Vessels

Data sources: US Navy fact sheets, Jane's Fighting Ships, research institution specifications. Verified July 2026.

Aircraft carriers have a draft around 11 to 12 metres. The USS Gerald R. Ford draws approximately 12.0 metres at full load displacement of about 100,000 tonnes. That is shallower than a container ship carrying a quarter of the displacement. The reason is similar to cruise ships: aircraft carriers have enormous beam (41 metres at the waterline for the Nimitz-class, 78 metres flight deck width) which provides stability without needing deep draft. Carrier draft is also constrained by naval base channel depths. Norfolk, San Diego, and Yokosuka all maintain dredged approach channels to specific depths, and carrier design must work within those limits.

Naval draft numbers should be treated as approximate. For operational security reasons, exact draft figures for warships and especially submarines are often withheld or published as ranges rather than precise values. The numbers cited here come from publicly available Jane's Fighting Ships data and US Navy fact sheets.

Heavy lift ships like Dockwise Vanguard deserve special mention. This is the vessel that transported the damaged USS Fitzgerald from Japan to the United States and carried the Costa Concordia wreck to Genoa for scrapping. Its operating draft varies enormously. Empty, it draws about 8 metres. With a loaded drillship or semi-submersible rig on deck, it draws 11 to 12 metres. But its most impressive capability is submersion: the deck can be flooded down to 16 metres below the waterline so that floating cargo like damaged warships or oil platforms can be floated on and off. At that submerged depth, Dockwise Vanguard essentially becomes a temporary deep-water port.

The World's Deepest Draft Vessels

Data sources: Guinness World Records, Euronav register, Vale SA fleet data, Allseas Group specifications. Verified July 2026.

Pioneering Spirit is an anomaly in this list. This is not a cargo ship. It is a catamaran-hulled offshore construction vessel owned by Allseas, designed to install and remove entire offshore platform topsides and pipelines. It is the largest vessel by gross tonnage (403,342 GT) currently in service. Its twin-hull design and variable ballast system allow it to adjust its draft from roughly 10 to 15 metres in transit mode to approximately 27 metres when flooded down for lifting operations. At 27 metres it is the deepest-draft vessel ever operated, though that is a working depth rather than a sailing draft. At 382 metres long and 124 metres wide, it is a unique vessel with no direct parallel.

The four TI-class supertankers (TI Europe, TI Oceania, TI Asia, TI Africa) are the deepest-draft conventional hulls still afloat. At 24.5 metres laden draft and roughly 441,500 DWT, they can only operate between a small number of deep-water terminals. All four have been converted to FSO service, with TI Asia and TI Africa off Qatar and TI Europe and TI Oceania off Malaysia. The economics of ULCC operation are marginal compared to the dominant VLCC fleet, which is why no ULCC has been built since 2003.

Seawise Giant at 24.6 metres remains the all-time draft record for a commercial vessel. When fully loaded with 4.1 million barrels of crude oil, the ship displaced approximately 657,000 tonnes of seawater. The hull depth was roughly 29.8 metres, meaning about 83% of the hull was submerged at full load. No commercial port in the world had a channel deep enough for the ship to enter at full draft. It offloaded at offshore moorings and transferred cargo to smaller tankers through ship-to-ship lightering operations.

Port and Canal Draft Restrictions

Major Canal Draft Limits

Data sources: Panama Canal Authority OP Notice N-1 (2024), Suez Canal Authority canal characteristics, Saint Lawrence Seaway Development Corporation. Verified July 2026.

Major Port Channel Depths

Data sources: Port authority publications, Admiralty sailing directions, industry port guides. Verified July 2026.

Under-Keel Clearance and Tidal Windows

The gap between a ship's keel and the seabed is under-keel clearance (UKC). Ports typically require minimum UKC of 10 to 15% of the vessel's draft. A container ship drawing 16 metres needs at least 17.6 to 18.4 metres of water depth. Ports publish their declared channel depth, and ship masters and pilots compare this against the vessel's actual arrival draft and the tide table.

Squat effect makes this more complicated. When a ship moves through shallow water, the water flowing under the hull accelerates, creating a low-pressure zone that pulls the hull deeper into the water. A ship drawing 16 metres at 12 knots in a constrained channel might squat an additional 0.8 to 1.2 metres. Pilots account for this by slowing down in shallow water, which is why ships creep through port approach channels at 6 to 8 knots rather than their open-water cruising speed.

Tidal windows are the operational solution when channel depth alone is insufficient. A ship arriving at Port Hedland with 18 metres of draft might need 19 metres of water depth for safe clearance. If the charted depth is 17 metres at low tide, the ship must arrive when the tide adds at least 2 metres of extra depth. Port Hedland's tidal range of roughly 3 to 7 metres (neap to spring tides) provides that window. But the window is narrow: arrive late and you wait 12 hours for the next high tide. At operating costs of $70,000 to $100,000 per day for a large bulk carrier, that delay erases margin quickly.

Ports that lack significant tidal range, especially in the Mediterranean and Baltic, must maintain deeper dredged channels because they cannot count on tide to provide temporary depth. Rotterdam's 24-metre Europort channel is dredged deep specifically because the Netherlands has a relatively modest tidal range of about 1.5 to 2 metres. Every metre of channel depth must come from dredging, not from tide.

Frequently Asked Questions

Which ship type has the deepest draft?

Why do cruise ships have such shallow draft?

Two reasons, both commercial. First, wide beam provides stability without deep draft. An Oasis-class ship has a beam of 47 metres at the waterline, which is more than five times the 9.3-metre draft. The large waterplane area creates a strong righting moment when the ship heels. Second and more important: shallow draft equals more ports. Every metre of draft eliminated opens up additional Caribbean, Mediterranean, and Southeast Asian ports that lack deep-water channels. Cruise revenue depends on itinerary flexibility, not cargo capacity. The naval architect's job is to keep the draft as shallow as the stability calculations will allow.

Why does container ship draft matter?

Container ship draft determines port access, and port access determines global supply chain routing. When a laden ULCV at 16.5 metres draft cannot enter a port because the channel is 15 metres deep, that ship either reduces cargo (losing revenue), waits for a tidal window (adding cost and delay), or skips the port entirely (disrupting supply chains). Ports invest hundreds of millions of dollars deepening channels by a single metre to keep their competitive position. The 130-million-pound channel deepening at Felixstowe was justified entirely by the need to handle 17-metre-draft ULCVs. Container ship draft is also the key input to draft survey cargo weight calculations, which settle billions of dollars in freight invoices annually.

What are the canal draft limits for ships?

The three major canal limits are: Panama Canal expanded locks at 15.24 metres (50 feet) in tropical fresh water, though drought forced reductions to 13.56 metres during 2022-2024; Suez Canal at 20.1 metres (66 feet), achieved by 2010 with the 2015 project doubling the bypass channel sections; and the Saint Lawrence Seaway at roughly 8.08 metres (26.5 feet), the most restrictive major waterway for deep-draft ocean shipping. Each limit has defined an entire ship class: Panamax, Neopanamax, Suezmax, and Seawaymax. Ships are designed to carry the maximum possible cargo while fitting within these canal draft constraints plus a small safety margin.

How can I find the draft of a specific ship?

You have several options. MarineTraffic and VesselFinder display real-time draft data from AIS transponders, but this data is manually entered by the crew and may lag actual conditions by hours. Classification society databases from Lloyd's Register, DNV, or Bureau Veritas list the design and scantling drafts for every registered vessel. The ship's own capacity plan and loading manual contain the official hydrostatic data including the summer load line draft. Port authority websites often publish maximum draft for vessels currently in berth. For any commercial purpose that depends on exact draft, cargo settlement, charter party disputes, insurance claims,AIS data should never be relied upon. Only a physical reading of the vessel's draft marks by a qualified surveyor provides verified draft data. See our guide to reading draft marks for the correct procedure.

References and Further Reading