Skip to content

How is cruise ship speed measured, and how fast is a knot in miles per hour?

July 12 2022
5 min read
This post contains references to products from one or more of our advertisers. We may receive compensation when you click on links to those products. Terms apply to the offers listed on this page. For an explanation of our Advertising Policy, visit this page.

Have you ever wondered how cruise ship speed is measured? Ships aren't the fastest method of transportation, but that doesn't mean it's not fun to calculate your speed when you're sailing. Unlike land travel, ship speed is not measured in miles per hour.

Here, I'll cover how cruise ship speed is measured, how to calculate your ship's speed in miles per hour and some considerations that could affect how fast you're going.

For cruise news, reviews and tips, sign up for TPG's cruise newsletter.

Sign up for our daily newsletter

What is a knot in nautical terms?

Sailors in the 17th century used ropes with knots to measure ship speed. (Photo by Westend61/Getty Images)

A knot is the nautical measure of speed used by cruise ships and other maritime vessels. One knot represents 1 nautical mile per hour.

But "knot" isn't simply a misspelled nickname for "naut" (as in nautical mile). Its origins are far more literal, according to the United States' National Ocean Service.

In the 17th century, ship crews measured vessel speed by tossing a rope with several evenly spaced knots and a triangular-shaped piece of wood into the water. As the ship moved, currents created resistance against the wood, causing more rope to be pulled into the water over a specified period of time. When time was up, crew members would pull the rope in and count the knots.

In short, the number of knots pulled out into the water over a specific period of time translated into the speed of the vessel's travel.

How fast is a knot in miles per hour?

When you convert 1 knot to miles per hour, it works out to 1.15 standard miles per hour for every nautical mile per hour. That's knot speed. So, although land-based miles per hour are just slightly faster than knots, for general purposes, it's a close comparison. For example, if your ship is sailing 20 knots, it's sailing roughly 23 mph.

How fast do cruise ships go?

Cunard Line's flagship, Queen Mary 2. (Photo by Angela Weiss/AFP/Getty Images)

What is the maximum speed of a cruise ship? The maximum speed for most modern vessels is about 30 knots or 34.5 mph, but just because they can glide along that fast doesn't mean they actually do, or at least not all the time.

Officers on the bridge will adjust speed to account for weather and ocean conditions — rough seas and high winds mean slower speeds — and port arrival times. Early arrival into port can come with extra fees that cruise lines are loath to incur, which usually means they prefer to take their time by slowing their speed.

What is the average cruise ship speed?

Cruise ship average speed is affected by lots of outside forces, as mentioned above. In relatively calm conditions, the average present-day vessel travels about 20 knots or 23 mph between ports of call.

What is the fastest cruise ship?

SS United States sits at a dock in Philadelphia. It is the fastest passenger ship on record. (Photo by dovate/Getty Images)

Currently, the fastest cruise ship that's operational is Cunard Line's Queen Mary 2, which often serves as an ocean liner to ferry people back and forth between the U.S. and the United Kingdom. Its maximum speed is 30 knots.

Cunard, which has operated historically fast vessels throughout the years, won the Blue Riband — a coveted prize for the ship to cross between the U.S. and Europe while maintaining the highest speed — 18 times. The last ship in the fleet to hold the unofficial award, which dates back to the 1800s, was Queen Mary, which is currently a floating hotel in Long Beach, California, near Los Angeles.

Queen Mary was dethroned as the winner in 1952 by SS United States, which was operated by rival United States Lines and made the crossing in just three days, 10 hours and 40 minutes at a speed of nearly 35.6 knots or almost 41 mph. (Its maximum speed was 39 knots or about 45 mph.)

Today, SS United States is docked in Philadelphia and maintained by a nonprofit conservancy that hopes to find investors to restore the languishing liner, which is now more than 70 years old. It might not be operational, but its previous accolades make it the fastest passenger vessel currently afloat.

Planning a cruise? Start with these stories:

Featured photo by Getty Images
Editorial disclaimer: Opinions expressed here are the author’s alone, not those of any bank, credit card issuer, airline or hotel chain, and have not been reviewed, approved or otherwise endorsed by any of these entities.

TPG featured card

Best Marriott card for Business Owners
TPG Editor‘s Rating
Card Rating is based on the opinion of TPG‘s editors and is not influenced by the card issuer.
3 / 5
Go to review

Rewards

2 - 6X points
6X6x points at hotels participating in the Marriott Bonvoy® program.
4X4x points for purchases made at restaurants worldwide, at U.S. gas stations, on wireless telephone services purchased directly from U.S. service providers and on U.S. purchases for shipping.
2X2x points on all other eligible purchases.

Intro offer

Limited Time Offer: Earn 100,000 points75,000 points
Limited Time Offer: Earn 100,000 Bonus Marriott Bonvoy Points after spending $4,000 in purchases on your new Card in your first 3 months of Card Membership. Offer expires 11/2/22.

Annual Fee

$125

Recommended Credit

670-850
Excellent/Good
Credit ranges are a variation of FICO© Score 8, one of many types of credit scores lenders may use when considering your credit card application.

Why We Chose It

The Marriott Bonvoy Business Amex is a stacked card with a rewards rate that will help you earn bonus points on everyday and business-related purchases. You'll earn 15 elite night credits each calendar year, and receive automatic Gold elite status. Finally, the free night award certificate with a redemption level of 35,000 points or less can get you hundreds of dollars in potential value each year.

Pros

  • 6x points on eligible purchases at hotels participating in the Marriott Bonvoy program
  • 4x points at restaurants worldwide, U.S. gas stations, wireless telephone services purchased directly from U.S. service providers and U.S. shipping
  • 2x points on all other eligible purchases
  • Earn a free-night award each card renewal month (up to 35,000 points)
  • Receive 15 elite night credits to jump-start status
  • Transfer Marriott points to 40+ airlines

Cons

  • Airline points transfer ratios are poor
  • Must spend $60,000 in a year for second free-night award
  • Limited Time Offer: Earn 100,000 Bonus Marriott Bonvoy Points after spending $4,000 in purchases on your new Card in your first 3 months of Card Membership. Offer expires 11/2/22.
  • 6x points at hotels participating in the Marriott Bonvoy® program.
  • 4x points for purchases made at restaurants worldwide, at U.S. gas stations, on wireless telephone services purchased directly from U.S. service providers and on U.S. purchases for shipping.
  • 2x points on all other eligible purchases.
  • Receive a 7% discount off standard rates for reservations of standard guest rooms at hotels that participate in the Marriott Bonvoy program when you book directly. Terms and Conditions Apply.
  • Receive 1 Free Night Award every year after your Card renewal month. Plus, earn an additional Free Night Award after you spend $60K in purchases on your Card in a calendar year. Awards can be used for one night (redemption level at or under 35,000 Marriott Bonvoy® points) at hotels participating in Marriott Bonvoy®. Certain hotels have resort fees.
  • Enjoy Complimentary Marriott Bonvoy Gold Elite Status with your Card.
  • Terms apply.
  • See Rates & Fees
Apply for Marriott Bonvoy Business® American Express® Card
at American Express's secure site
Terms & restrictions apply. See rates & fees
Best Marriott card for Business Owners
TPG Editor‘s Rating
Card Rating is based on the opinion of TPG‘s editors and is not influenced by the card issuer.
3 / 5
Go to review

Rewards Rate

6X6x points at hotels participating in the Marriott Bonvoy® program.
4X4x points for purchases made at restaurants worldwide, at U.S. gas stations, on wireless telephone services purchased directly from U.S. service providers and on U.S. purchases for shipping.
2X2x points on all other eligible purchases.
  • Intro Offer
    Limited Time Offer: Earn 100,000 Bonus Marriott Bonvoy Points after spending $4,000 in purchases on your new Card in your first 3 months of Card Membership. Offer expires 11/2/22.

    Limited Time Offer: Earn 100,000 points
    75,000 points
  • Annual Fee

    $125
  • Recommended Credit
    Credit ranges are a variation of FICO© Score 8, one of many types of credit scores lenders may use when considering your credit card application.

    670-850
    Excellent/Good

Why We Chose It

The Marriott Bonvoy Business Amex is a stacked card with a rewards rate that will help you earn bonus points on everyday and business-related purchases. You'll earn 15 elite night credits each calendar year, and receive automatic Gold elite status. Finally, the free night award certificate with a redemption level of 35,000 points or less can get you hundreds of dollars in potential value each year.

Pros

  • 6x points on eligible purchases at hotels participating in the Marriott Bonvoy program
  • 4x points at restaurants worldwide, U.S. gas stations, wireless telephone services purchased directly from U.S. service providers and U.S. shipping
  • 2x points on all other eligible purchases
  • Earn a free-night award each card renewal month (up to 35,000 points)
  • Receive 15 elite night credits to jump-start status
  • Transfer Marriott points to 40+ airlines

Cons

  • Airline points transfer ratios are poor
  • Must spend $60,000 in a year for second free-night award
  • Limited Time Offer: Earn 100,000 Bonus Marriott Bonvoy Points after spending $4,000 in purchases on your new Card in your first 3 months of Card Membership. Offer expires 11/2/22.
  • 6x points at hotels participating in the Marriott Bonvoy® program.
  • 4x points for purchases made at restaurants worldwide, at U.S. gas stations, on wireless telephone services purchased directly from U.S. service providers and on U.S. purchases for shipping.
  • 2x points on all other eligible purchases.
  • Receive a 7% discount off standard rates for reservations of standard guest rooms at hotels that participate in the Marriott Bonvoy program when you book directly. Terms and Conditions Apply.
  • Receive 1 Free Night Award every year after your Card renewal month. Plus, earn an additional Free Night Award after you spend $60K in purchases on your Card in a calendar year. Awards can be used for one night (redemption level at or under 35,000 Marriott Bonvoy® points) at hotels participating in Marriott Bonvoy®. Certain hotels have resort fees.
  • Enjoy Complimentary Marriott Bonvoy Gold Elite Status with your Card.
  • Terms apply.
  • See Rates & Fees