Panamax

The two ships seen here seem almost to be touching the walls of the Miraflores Locks.

Panamax and New Panamax are popular terms for the size limits for ships traveling through the Panama Canal. Formally, the limits and requirements are published by the Panama Canal Authority (ACP) titled "Vessel Requirements".^[1] These requirements also describe topics like exceptional dry seasonal limits, propulsion, communications and detailed ships design.

The allowable size is limited by the width and length of the available lock chambers, by the depth of the water in the canal and by the height of the Bridge of the Americas. Consequently, ships that do not fall within the Panamax-sizes are called Post Panamax. The limits have influenced those constructing cargo ships, giving clear parameters for ships destined to traverse the Panama Canal.

"Panamax" has been in effect since the opening of the canal in 1914. In 2009 the Canal management published the "New Panamax",^[2] that will be in effect when the third lane of locks, larger than the current two, are operational from 2014.

The increasing prevalence of vessels of the maximum size is a problem for the canal as a Panamax ship is a tight fit that requires precise control of the vessel in the locks, possibly resulting in longer lock time, and requiring that these ships transit in daylight. Because the largest ships traveling in opposite directions cannot pass safely within the Gaillard Cut, the canal effectively operates an alternating one-way system for these ships.

Panamax dimensions

An officer monitors the clearance of the cruise ship Ryndam as she traverses the lock.

Panamax container ship

Panamax is determined principally by the dimensions of the canal's lock chambers, each of which is 110 ft (33.53 m) wide by 1,050 ft (320.04 m) long, and 85 ft (25.91 m) deep. The usable length of each lock chamber is 1,000 ft (304.8 m). The available water depth in the lock chambers varies, but the shallowest depth is at the south sill of the Pedro Miguel Locks and is 41.2 ft (12.56 m) at a Miraflores Lake level of 54 ft 6 in (16.61 m). The height of the Bridge of the Americas at Balboa is the limiting factor on a vessel's overall height.

The maximum dimensions allowed for a ship transiting the canal are:^[1]

Length

Over all (including protrusions): 950 ft (289.56 m) Exceptions:

• Container ship and passenger ship: 965 ft (294.13 m)
• Tug-barge combination, rigidly connected: 900 ft (274.32 m) over all
• Other non-self-propelled vessels-tug combination: 850 ft (259.08 m) over all

Width (beam)

Width over outer surface of the shell plating: 106 ft (32.31 m) General exception: 107 ft (32.61 m), when draft is less than 37 ft (11.3 m) in tropical fresh water.

Depth (draft)

In tropical fresh water 39.5 ft (12.04 m). ACP uses the freshwater Gatun Lake as a reference. The salinity and temperature of water affect its density, and hence how deep a ship will float in the water. When the water level in Lake Gatún is low during an exceptionally dry season the maximum permitted draft may be reduced.

Air draft

190 ft (57.91 m) measured from the waterline to the vessel's highest point; limit also pertains to Balboa harbor. Exception: 205 ft (62.5 m) with passage at low water (MLWS) at Balboa is possible

All exceptions are typically allowed only after specific request, an investigation and on a one- or two-time only basis.

A Panamax cargo ship would typically have a DWT of 65,000–80,000 tonnes, but its maximum cargo would be about 52,500 tonnes during a transit due to draft limitations in the canal.^[3]

The longest ship ever to transit was the San Juan Prospector, now Marcona Prospector, an ore-bulk-oil carrier that is 973 ft (296.57 m) long, with a beam of 106 ft (32.31 m).^[4] The widest ships to transit are the two North Carolina class battleships, USS North Carolina (BB-55) and USS Washington (BB-56), which have beams of 108 ft (32.92 m).^[5]

Post-Panamax ships

Post-Panamax or over-Panamax denote ships larger than Panamax that do not fit in the canal, such as supertankers and the largest modern container ships. The "largest oil tanker in the world"—whichever ship held the title at the time—has not been able to transit the Panama Canal at least since the Idemitsu Maru was launched in the 1960s; she was about 150,000 deadweight tons. U.S. Navy supercarriers are also in the post-Panamax class; the Nimitz class aircraft carriers are 1,092 ft (332.84 m) long overall with a beam of 134 ft (40.84 m), while the flight deck is 252 ft (76.81 m) wide.

2006 Expansion plan and the New Panamax

USS Missouri, one of the Iowa-class battleships, makes a very tight fit as she passes through the Miraflores Locks of the Panama Canal in October 1945.

Main article: Panama Canal expansion project

As early as the 1930s, new locks were proposed for the Panama Canal to ease congestion and to allow larger ships to pass. The project was abandoned in 1942.

On October 22, 2006, the Panama Canal Authority (with the support of the Electoral Tribunal) held a referendum for Panamanian citizens to vote on the Panama Canal expansion project. The expansion was approved by a wide margin, with support from about 78% of the electorate. It is estimated that the project will be completed by 2014 and will cost $5.3 billion; this sum is expected to be recovered within 11 years.

New Panamax

The plans to build bigger locks have led to the creation of "New Panamax", based on new lock dimensions of 1,400 ft (427 m), beam 180 ft (55 m) and depth 60 ft (18.3 m).^[2] Naval architects and civil engineers are already taking into account these dimensions for container ships.^[6] The world's largest cruise ship, the Oasis of the Seas, has almost New Panamax dimensions but her height may prevent her passing under the Bridge of the Americas even at low tide.

After this expansion, the Panama Canal will be able to handle vessels of cargo capacity up to 13,000  Twenty-foot equivalent units (TEU);^[7] currently, it can only handle vessels up to about 5,000 TEU.^[8] A third set of locks—1,400 ft (426.72 m) long, 180 ft (54.86 m) wide, with a draft of 60 ft (18.29 m)—will supplement the two existing sets.

However, even before the revised dimensions were announced, the Maersk E-class—like the Emma Maersk, the future Maersk Triple E Class, as well as many large tankers (ULCCs) and some bulk carriers (VLOCs)—will not be able to pass through even the new, much larger locks. The Maersk E and Triple E Class are too wide for even the new locks.

Several ports, including the ports of New York, Norfolk, and Baltimore, all in the northeastern US, have already increased their depth to at least 50 feet (15 m) to accommodate these changes, and the Port of Miami has recently approved doing the same in a project known as the "Deep Dredge"^[9] and will be the closest deep water port to the Panama Canal in the US.

Comparison of sizes

Comparison of bounding box of Panamax and New Panamax with some other sizes in isometric view.

	Locks	Panamax	New locks	New Panamax1
Length	1,050 ft (320.04 m)	965 ft (294.13 m)	1,400 ft (427 m)	1,200 ft (366 m)
Width	110 ft (33.53 m)	106 ft (32.31 m)	180.5 ft (55 m)	160.7 ft (49 m)
Depth, draft2	41.2 ft (12.56 m)	39.5 ft (12.04 m)	60 ft (18.3 m)	49.9 ft (15.2 m)
TEU		5,000		12,000
1New Panamax sizes are published in metric system[2] 2Draft in Tropical Freshwater (TF)

References

1. ^ ^{a b} (PDF) Vessel Requirements, Panama Canal Authority, http://www.pancanal.com/eng/maritime/notices/n01-05.pdf .
2. ^ ^{a b c} Manuel E. Benítez, ACP (19-01-2009). "Dimensions for Future Lock Chambers and "New Panamax" Vessels" (PDF). ACP. http://www.pancanal.com/common/maritime/advisories/2009/a-02-2009.pdf. Retrieved 02-05-2010. 
3. ^ (PDF) Modern ship size definitions, Lloyd's register, http://www.lr.org/Images/30%20ship%20sizes_tcm155-173543.pdf .
4. ^ Background of the Panama Canal, Montclair State University, http://rainforest.montclair.edu/pwebrf/rainforest/Region/panama.html .
5. ^ Garzke, Jr, Robert O; Dulin, Jr, William H (1976), Battleships, United States Battleships in World War II, Naval Institute Press, pp. 62, 145, ISBN 0-87021-099-8 .
6. ^ (PDF) Propulsion Trends in Container Vessels, MAN B&W Two-stroke Engines, http://www.manbw.com/files/news/filesof4672/Propulsion_trends_in_container_vessels.pdf .
7. ^ "Maersk Edinburgh" 13,000 TEU container ship" (PDF), Fleet, Rickmers Maritime, http://www.rickmers-maritime.com/fleet/MAERSK%20EDINBURGH_RM.pdf .
8. ^ ""Maersk Djibouti" 5,000 TEU container ship" (PDF), Fleet, Rickmers Maritime, http://www.rickmers-maritime.com/fleet/MAERSK%20DJIBOUTI_RM.pdf .
9. ^ http://www.dredgingtoday.com/2010/11/24/usa-port-of-miami%E2%80%99s-deep-dredge-project-to-boost-economic-growth/

External links

• Vessel size groups