You’ve probably heard the terms before: Panamax and Post-Panamax. But what are they, and what do they mean?

Both terms have a single commonality: they’re both used to describe size in relation to the maximum dimensions of the locks in the Panama Canal.  Each lock has a set of maximum dimensions that restrict the width, length, and draught of a ship transiting through it.  A Panamax ship is one that meets these requirements; a Post-Panamax ship does not.

Three ships docked together in Nassau. Two are Panamax, one is Post-Panamax. Any guesses as to which one is too large to transit the Panama Canal? Photo © 2012 Aaron Saunders

So why does that matter to you? Well, technically, it doesn’t – unless you’re wondering why your favorite cruise ship doesn’t offer Panama Canal sailings.

Panamax dimensions limit cruise ships capable of transiting the Panama Canal to a maximum length of 965 feet.  The maximum width (of the hull itself, not including navigation bridge wings) is 107 feet. And the maximum draught (the area of the ship that exists below the waterline) tops out at 39.5 feet.

Post-Panamax ships, on the other hand, can be described as any vessel larger than the above requirements.

Mariner of the Seas at anchor off Cabo San Lucas, Mexico. Because of her Post-Panamax size, she had to sail around South America in order to reposition to the West Coast. Photo © Aaron Saunders

For cruise lines, the implications of building a Post-Panamax ship require some careful thought. Say a cruise line wants to take their latest-and-greatest and reposition it from Miami to Los Angeles.  If the ship is a Panamax ship, they can simply offer a leisurely 15-day Panama Canal voyage between the two cities.  But if their ship is Post-Panamax, redeploying it to the West Coast requires over a month’s worth of sailings and itineraries that loop around the horn of South America.

A great example of this logistical tightrope occurred in 2009, when Royal Caribbean replaced its Vision of the Seas on the Mexican Riviera run out of Los Angeles with the much-larger Mariner of the SeasVision, as a Panamax ship, was simply able to sail through the Panama Canal and on to Europe, its new deployment run.  But Mariner of the Seas was forced to sail around the tip of South America to reach Los Angeles.  It was a worthy excursion, but when the Mexican Riviera run began to lose revenue and Royal Caribbean made the decision to pull Mariner in early 2011, it was back for another trip around the horn.

Princess Cruises’ 2004-built Sapphire Princess, shown here in Ketchikan, Alaska in August, is an example of a Post-Panamax ship. Photo © 2012 Aaron Saunders

Holland America Line’s Zuiderdam docked in Skagway, Alaska. She can fit through the Panama Canal – but just barely. Photo © 2012 Aaron Saunders

Princess CruisesSapphire Princess is an excellent example of a Post-Panamax ship. At 952 feet, it is short enough to fit the maximum length requirement, but her beam of 121 feet makes her too wide to squeeze through.  But Holland America Line’s similarly-sized Zuiderdam can fit through with ease; she is only 106 feet wide.

Can your cruise ship fit through the Panama Canal? Photo © 2012 Aaron Saunders

So if you’ve ever wondered why Disney Wonder can transit the Panama Canal, but Disney Fantasy never seems to …the answer is truly in the details.


5 Responses to Panamax vs. Post-Panamax

  1. Nicholas Sabalos, Jr., CDR, U.S. Navy (Ret.) says:

    Great explanation, Aaron!

    Of course, soon, we will need to redefine the term “Panamax” as the larger locks come into operation in the next few years (2014>).

    There is already a new term coming into play: “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).

    Most current cruise ships will be able to transit the widened canal….but some like Oasis of the Seas and Allure of the Seas, while fitting the new locks, they will not be able to pass under the Bridge of the Americas even at low tide.

    • Aaron Saunders says:

      Right you are, Nicholas. The expansion of the Panama Canal will allow a whole host of new ships to pass through – provided their air draft is low enough to clear the bridge. That still leaves ships like Oasis, Queen Mary 2, and Norwegian Epic out of the running because of their height.

  2. […] And finally a photo of three more cruise ships ripped from the blog of Aaron Saunders. […]

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