Cruise ships are not designed to go fast. Unlike ocean liners that once sailed regularly between the UK and United States across the Atlantic, most cruise ships are designed to go relatively slow at a steady pace with passenger comfort and environmental efficiency the primary consideration. This is a key difference since it is rare that you will see a cruise ship travel at maximum speed and so there is the practical speed that you might experience as a cruise passenger and the maximum theoretical speed that you might see listed alongside other statistics about an individual cruise ship.
Cruise Ship Top Speed vs Ocean Liner Top Speed
Novice cruisers might get ocean liners and cruise ships confused but while they each are designed to carry passengers on vacation, they are designed for different purposes. Ocean Liners such as Cunard Line's Queen Mary 2 (currently the world's fastest ocean liner) are designed as transportation taking people from one destination to the next as quickly as possible. The modern cruise ship evolved from ocean liners but on an Alaska cruise for instance, the ports are close together so you don't necessarily need to go faster. A difference between 18 knots and 30 knots (35 mph) might only make the difference.
As an example, consider two Alaska cruise ships ports of Juneau and Skagway. They are roughly 86 miles apart. At 30 knots this is a 2 hour and 52-minute journey but at 22.5 knots (Norwegian Bliss top speed) the journey is 3 hours 49 minutes. While that's an extra 1 hour of travel time at max speed, the reality is that there's no need to even go that fast between those two ports. In fact, on one Alaska cruise itinerary for 2021, Norwegian Bliss is scheduled to depart Juneau at 11 pm on Monday and arrive in Skagway at 7 am the next morning. That's a scheduled journey of eight hours or an average speed of only 10.7 knots.
On the other hand, an ocean liner such as Queen Mary 2 traveling from Southhampton, England, UK to New York City travels a distance of roughly 3,000 miles with no port calls. That voyage is approximately 100 hours of travel time over seven days at the Queen Mary 2's top speed of 30 knots. While Norwegian Bliss doesn't do point to point transatlantic cruises like this, that same voyage at her top speed of 22.5 knots would add an extra 33 hours of travel time! However, even in this theoretical scenario, you'll notice that you could travel that distance in just over 4 days at top speed, but Cunard schedules her to do the journey over the course of six full days at sea.
Just like with air travel, you'll notice that older ocean liners actually traveled faster. In fact, the SS United States remains the fastest ocean liner ever built and it averaged 34.51 knots on its record-breaking transatlantic maiden voyage in 1951.
As you compare how fast cruise ships go compared to ocean liners, you will also notice other design elements that allow an ocean liner to travel faster through the water. This includes a generally more sharply angled bow and narrower beam. These all help reduce friction and help make the ship sail faster from port to port. Today's cruise ships - while still designed to carry passengers on vacation - are a completely different type of ship.
So, How Fast Does A Cruise Ship Go?
A cruise ship on the other hand isn't focused on traveling as fast as possible. The question of, "How fast is a cruise ship?" is a bit more complicated since the speed of a cruise ship is dictated as much by fuel economy as it is by the ability of cruise ship engineers and the captain's desire to go fast. In fact, just like the scenario above with Alaska cruises, with Caribbean cruises, and west coast cruises to Mexico, you'll notice the same pattern. With a few exceptions - such as cruises from San Diego and Los Angles to Hawaii, most cruise ports on your itinerary are close enough to allow the ship to travel overnight. This is why your port departure time might vary sometimes from 4 pm to 7 pm but you almost always arrive sometime around 7-8 am, just in time to start your day exploring the destination.
In my experience, a cruise ship almost never travels the full speed. Instead, you'll notice that 18-20 knots is about the average cruising speed of a cruise ship. This allows the ship to cut through the waves easily for maximum passenger comfort while still having extra speed available if the captain needs the ship to avoid weather or there's an issue somewhere that delays departure or arrival.
When it comes to designing new cruise ships, speed is absolutely taken into account. For instance, you will notice that on average ships from Carnival Cruise Line are slightly slower than those from Holland America Line. This is because while Carnival's cruise ships are designed to travel slowly between ports that are close together in the Caribbean primarily, Holland America Line cruise ships often travel long distances between ports and so speed is an important factor that could reduce a voyage with three sea days to only two for instance.
Interestingly though, while you would think that smaller cruise ships could travel faster, this isn't always true. For example, Viking Ocean's current generation of cruise ships such as the Viking Star (47,842 GT) is rated at only 20 knots maximum speed with a 17-knot service speed. Compare that to 79,300 for Queen Mary 2 and 168,028 for Norwegian Bliss. Royal Caribbean's Symphony of the Seas and Odyssey of The Seas have a max speed of 22 knots.
Small Luxury Cruise Ships Speeds Also Aren't Fast
You might think that small luxury cruise ships where saving money wasn't as important would be much faster. However, once again we find that cruise ship speed is dictated by practicality rather than how fast can they go.
For instance, Scenic Eclipse (17,545 GT), one of the most advanced and certainly among the most luxurious small ships is only able to travel at 17 knots with a maximum of 19.5. The same holds true for Seabourn Ovation (41,865 GT) who's cruising speed is 15 knots with a maximum speed of 18.6. Both ships are brand new and certainly could travel faster if they needed to but that's not the point.
When it comes to looking at how fast does a cruise ship go, the answer isn't technology or physical limitations. Instead, it is about how fast does a cruise ship need to go, combined with how much will it cost to go faster. Ultimately this is why, even as slow as cruise ships are compared to what you might think, they are among the fastest non-military vessels. For example, while a typical cruise ship might travel at an average speed of 20 knots, container ships travel at 16 knots and tankers travel at 13 knots.
With environmental concerns being a huge issue with cruise ship travel, it is unlikely that even the most luxurious cruise ships will challenge these speeds. In fact, Cunard Line's ships that have followed the Queen Mary 2 are also both smaller (90,901 GT) and sail at 23.7 knots. It is likely that their next vessel, currently unnamed but due in 2022 based on Holland America Line's Koningsdam, will be even slower since that vessel is rated at 18 knots with a maximum speed of 22 knots.