On October 30th 2010, one of the largest cruise ship ever built at that time, the Allure of the Seas, successfully passed under the Storebaelt Bridge in Denmark. The Allure of the Seas has a height of 72 meters above waterline, far exceeding the safety height of 65 meters needed to pass under the Storebaelt Bridge. So, how did it work?
Allure of the Seas under the Storebaelt Bridge (photo credit: Martin Nikolaj Christensen CC-BY-20)
This article is co-written with our invited member, The Seal, of the RList.io community.
Outline
1. Cruise Ship Measurements
Draught or draft. The draught (or draft) is the vertical distance between the waterline and the bottom of the ship's hull (keel). This measurement determines the minimum depth of water required for the ship to safely float over and is an important consideration when navigating shallow waters.
Height. The height above waterline measures the vertical distance between the waterline and the highest point of the ship. When passing under a bridge, the ship captain needs to ensure that the height of the ship above waterline is sufficiently below the clearance height of the bridge.
Beam. The beam is a measure of the width of the ship. Thus, the beam at waterline refers to the width of the ship at the water line level. When crossing a tight canal, the ship captain needs to ensure that the width of the canal at waterline is sufficiently wider than the waterline beam and the width of the terrain flanking the canal is sufficiently wider than the maximum beam.
Ship Length. Likewise, when crossing a canal or narrow passageway, the captain needs to ensure that the curvature of the canal at waterline can sufficiently accommodate the waterline length of the ship, while the curvature of the terrain flanking the canal can sufficiently accommodate the overal length of the ship.
2. Allure of the Seas vs the Storebaelt Bridge
Allure of the Seas passing below the Storebaelt Bridge
The mammoth cruise ship Allure of the Seas managed to pass under the Storebaelt Bridge or Great Belt Bridge of Denmark successfully, with barely a foot of margin, on October 30, 2010, at 1420GMT. The Allure of the Seas is 72 meters tall above the waterline, while the Storebaelt Bridge has a clearance height of 65 meters.
To get below the clearance height, the Allure of the Seas crew lowered the ship's retractable twin smokestacks. Next, the crew adjusted the ship's ballast and increased its cruising speed so that the ship would dip deeper into the water. These measures increased the draught (or draft) of the ship and reduced its height above waterline to barely accommodate the clearance height of the bridge by a thin margin.
3. The Super-tight Corinth Canal
Fred Olsen's Braemar - the largest cruise ship to cross the Corinth Canal
The scenic Corinth Canal is a narrow passageway that connects the Gulf of Corinth in the Ionian Sea with the Saronic Gulft in the Aegean Sea. It is 6.4 kilometers long and bears a width of 24 meters at its narrowest point. In addition, it is crossed by rail, vehicles and foot via a 45-meter tall bridge.
On October 9, 2019, Fred Olsen Cruise Lines's Braemar became the largest and longest cruise ship to cross the Corinth Canal successfully. The 7-deck Braemar stretches 195.82 meters in overall length and is 22.52 meters wide. In other words, the 929 guests on Braemar could possibly come as close as less than 1 meter from the cliffs that flank the Corinth Canal at its narrowest point.
4. The Panamax/New Panamax
Norwegian Bliss - largest cruise ship to cross the Panama Canal
The Panamax and the New Panamax (or Neopanamax) refer to specifications of allowable size limits for ships travelling through the Panama Canal. The Panamax (length:289.56m, beam:32.31m, draft:12.04m, height:57.91m) is intended for ships transiting the original set of locks, while the New Panamax (length:366m, beam:51.25m, draft:15.2m, height:57.91m) is intended for ships travelling via the newer set of locks at the Panama Canal.
On May 14, 2018, the Norwegian Bliss became the largest cruise ship to passes through the Panama Canal, two years after the official launch of the ew Panamax locks into operations. With an overall length of 333.32 meters and a maximum beam of 48 meters, the 20-deck, 4000-passenger cruise ship barely met the New Panamax specifications and successsfully made history as the largest cruise ship to traverse the Panama Canal.
5. The Lions' Gate Bridge
Ovation of the Seas - crossing under the Lions' Gate Bridge (passenger's view)
The Lions' Gate Bridge of Vancouver - a suspension bridge that stands 111 meters tall and 1.8 kilometers long - has a clearance height of 61 meters.
In May 12, 2019, the Ovation of the Seas became the largest cruise ship to pass under the Lions' Gate Bridge. The passing was executed at low tide and gave the Ovation of the Seas a sufficient clearance of around 5 meters at the point of crossing.
6. Other Narrow Bridge Passings
Dream Cruises' Explorer Dream, with a normal height above waterline of 49.6 meters, navigates under the 49-meter tall Sydney Harbourfront Bridge as lower tides.
Explorer Dream passing just under the 49-meter tall Sydney Harbourfront Bridge (bridge view)
Royal Caribbean's Anthem of the Seas barely passing under the Verrazano-Narrows Bridge of New York, which has a clearance height of 70 metesr.
Anthem of the Seas at Verrazano-Narrows Bridge, New York
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This article is co-written with our invited member, The Seal, of the RList.io community.
