Have you ever wondered how fast a cruise ship can go?
It all depends on the design of the ship and the power of its engine.
Ship builders design cruise ships for passenger comfort first and foremost, not for breaking speed records. To ensure a smooth ride, a large portion of a cruise ship’s hull is below the water. This greatly improves stability, but it also means increased water resistance and therefore slower speeds.
Nautical engineers are constantly working to design a cruise ship that offers a comfortable voyage for passengers while using the least amount of fuel. Improvements to hydrodynamic design, new engine types, and innovative technology have allowed ships to be more efficient as they have gotten bigger. For instance, some new cruise ships have a bubble system under the hull that creates a cushion of tiny air bubbles which lubricates the water, reduces drag, and increases fuel efficiency.
How is the speed of a ship measured?
The Knot
A knot is a reference to an archaic form of measurement. Until the mid-19th century, a captain measured his ship’s speed by tossing a log overboard. The log was attached to a rope with knots tied in it. As the log floated out behind the ship, the rope was let out. A sailor would count how many of the knots in the rope passed through his fingers in a 30-second time period, and thus know how fast the ship was traveling.
These days, the ship’s crew relies on GPS to determine their position and speed. A knot has been standardized to equal one nautical mile per hour.
The Nautical Mile
Yes, a nautical mile is slightly different than a regular mile – about 15% different, actually.
One nautical mile = 1.1508 statute mile
A nautical mile is equal to one minute of latitude. Latitude is the measurement along the Earth’s north-south axis. The distance from the North to the South Pole is divided into degrees, with the South Pole designated as – 90° and the North Pole as 90°. The distance between a degree of latitude is very consistent no matter where you are on Earth – 364,000 feet or 69 miles. One minute of latitude is 1/60 of a degree. Therefore, one nautical mile is 6,068 feet or 1.15 miles.
Latitude versus Longitude
You may wonder why mariners use latitude, rather than longitude, to determine the length of a nautical mile. Longitude is the east-west measurement around the Earth. This is measured in degrees and minutes, too, but the distance can vary depending on how close to the equator the measurement is taken. At the equator, a degree of longitude is 69.172 miles. But that gradually shrinks until you reach the poles, where all the longitudinal lines converge and the distance between them is zero.
Using latitude and longitude is a more practical and accurate way for sailors to calculate travel, due to the long distances covered at sea. In addition, nautical charts all use latitude and longitude, so it’s easy to measure distance this way.
Average Speed of Cruise Ships
The average cruise ship sails along at an optimal speed of 20 knots. Since one knot is equal to 1.15 miles per hour, a cruise ship traveling at 20 knots is going 23 mph. For comparison, your average fishing boat goes about 30 mph. And the SeaDoo RXPX, the fastest jet ski in the world, maxes out at 70 mph.
But, cruise ships can go faster than 23 mph when necessary. The captain reserves his ship’s top speeds for when he needs to outrun a storm or come to the aid of another vessel in distress. In general, a cruise ship’s top speed is about 5 mph faster than its regular “service speed”.
The captain will adjust the cruise ship’s speed according to the situation, like when avoiding glaciers and icebergs on an Alaska cruise or an Antarctica cruise. And while a captain may increase speed to go around a hurricane on a Caribbean cruise, if he gets stuck in one, he will definitely pull back the throttle! During adverse weather, cruise ships go as slow as 10 knots, or 12 mph. Sometimes, local regulations limit the speed of vessels, like in the Strait of Gibraltar. And of course, coming into port, cruise ships typically slow down to 5 knots as they initiate docking procedures.
While some cruise ships are able to achieve close to 30 knots, they rarely travel this fast. Modern cruise ships are enormous, and it takes a substantial amount of fuel to get them moving. The faster a ship goes, the more fuel it will burn, and the more it will cost the cruise line to move from point A to point B. Cruise ships can use up to 50 tons of fuel per day when traveling at high speeds.
Faster speeds can also lead to an uncomfortable bumpy ride sure to cause seasickness in the cruise passengers. So traveling at a more tranquil speed maximizes both cruise line profits and passenger satisfaction!
What is the Fastest Cruise Ship in the World?
This record is rather controversial, because there is no clear definition of what makes a cruise ship. Both Carnival and Royal Caribbean have ships in their fleet that can go over 25 knots.
The SS United States has the all-time record for the fastest ocean liner in the world. (Ocean liners are primarily for transportation across the seas and are classified separately from a cruise ship where the voyage itself is the primary purpose of the trip.) During her maiden voyage in 1952, the USS United States reached a speed of 38 knots or nearly 44 mph. She was withdrawn from service in the 1970s when her original cruise line went out of business. While several other companies purchased her, none were able to make a profitable venture. The SS United States is now docked in Philadelphia a state of dis-repair, waiting for a conservancy group to raise enough funds to revitalize her.
The Queen Mary 2 holds the record for the world’s fastest ocean liner currently sailing. Incidentally, she is also the only true ocean liner currently in service. She was purpose-built to make regular crossings of the Atlantic Ocean for Cunard Cruise Line. The Queen Mary 2 can reach speeds of up to 30 knots, or almost 35 mph. That is how Cunard can offer transatlantic voyages of just 7 days. She sails between Southhampton, England, and New York City as part of an annual world cruise.
Check out our video on How Fast does a Cruise Ship Go?, part of our First-Time Cruiser FAQs series.
