Transatlantic Cruise Time Changes: 23-Hour and 25-Hour Days Explained

On a transatlantic cruise, the ship changes its clocks one hour at a time until it reaches the time zone at the other end. Most changes happen overnight on sea days, and each is announced in the daily program. Sailing westbound from Europe to the US, the clocks go back an hour on five or six nights, which gives you 25-hour days. Sailing eastbound from the US to Europe, they go forward, which gives you 23-hour days.

The total is set by geography: Florida to Barcelona is six hours for most of the year, and New York to Southampton is five. Spread over a week at sea, either direction is far gentler than flying, and most passengers step off the ship with little or no jet lag.

Time differences on the main repositioning routes

The Pacific routes look strange because they cross the international date line, where the calendar jumps a day instead of the clock moving 24 hours. More on that below.

How ships make the change

Every line handles the clocks slightly differently, but the pattern is consistent:

• One hour at a time. Ships rarely change by more than an hour in a day, so the body can keep up.
• Overnight, usually. The most common time is 2 a.m., sometimes midnight. You go to bed on one time and wake up on the next.
• On sea days. Ships avoid changing clocks the night before a port, because shore excursions, tender times and all-aboard times run on local time.
• Announced ahead. The daily program, the app and the captain’s noon announcement all confirm the change. The cabin TV or the app usually shows ship time.
• Sometimes at midday. On eastbound crossings, some ships move the change to noon, so the hour disappears from the afternoon rather than from your sleep. Cunard has used this on some Queen Mary 2 crossings. See Cunard repositioning cruises.

Because the changes cluster in the open-ocean stretch, they often come on consecutive nights. On a Florida to Barcelona crossing, you might have five or six in a row between Bermuda or Florida and the Azores or Madeira. For route details, see repositioning cruises from Florida to Europe and westbound transatlantic repositioning cruises.

Daylight saving time makes it messier

Europe and the US start and end daylight saving time on different dates, so the gap between them changes for a few weeks each spring and fall.

• Fall: Europe ends daylight saving time on the last Sunday of October (October 25, 2026, and October 31, 2027). The US ends it on the first Sunday of November (November 1, 2026, and November 7, 2027). In that week, Florida and Spain are five hours apart, not six.
• Spring: the US starts daylight saving time on the second Sunday of March (March 14 in 2027), and Europe on the last Sunday of March (March 28 in 2027). In those two weeks, the gap is also five hours instead of six.

A crossing that starts before one change and ends after the other can need an extra clock change or one fewer. A westbound ship that leaves Barcelona before October 25 and reaches Florida after November 1 has seven hours to make up. The daily program will show exactly what the ship is doing, so there is nothing to calculate yourself, but it explains why your count might not match someone else’s crossing.

Which direction is easier on the body

Westbound is easier. The CDC’s jet lag guidance explains that the body clock naturally runs slightly longer than 24 hours, so it is easier to delay it than to advance it. The CDC puts typical adjustment at about 1.5 hours a day westward and about 1 hour a day eastward.

That matches how crossings feel:

• Westbound, 25-hour days: most people enjoy them. You get an extra hour of sleep, or a later evening, and arrive in the US fully adjusted.
• Eastbound, 23-hour days: one hour a night is within what most people can absorb, but five or six in a row can leave you tired around the middle of the crossing. Mornings feel early, and evening shows can seem late.

Either way, it beats flying. A flight from Miami to Barcelona asks your body to absorb six hours overnight. A cruise asks for one hour a day.

How to handle the 23-hour days

The CDC’s guidance on shifting the body clock applies at sea as well as in the air:

• Get bright light in the morning when traveling east. A walk on the open deck after breakfast helps advance your body clock.
• Avoid bright light late in the evening on eastbound nights, and on westbound nights, evening light helps you stay up for the extra hour.
• Go to bed a little earlier on nights when the clocks go forward.
• Limit alcohol and late caffeine. The CDC notes both fragment sleep.
• Melatonin: the CDC says low doses are often enough when timed correctly. Ask your doctor or pharmacist before using it, particularly with other medications.

If you take medication on a strict schedule, such as insulin or some heart medications, ask your doctor before the trip how to shift the timing across five or six time changes. Do not guess.

What a run of clock changes does to the week

The changes affect the whole crossing, and the mornings are only the start. On an eastbound voyage from Florida, the first sea days feel normal, but by the third or fourth consecutive 23-hour day many passengers notice that breakfast comes around fast, the gym is emptier at 7 a.m., and the late show feels later than it did. Some ships shift more of the program into the afternoon on those days.

Dining times stay fixed on the clock, which means your body is eating earlier each day in eastbound terms. People on fixed early dining sometimes switch to a later seating or flexible dining partway through. Westbound, the effect runs the other way: dinner at 6 p.m. feels increasingly late to the body, and many people find themselves waking before dawn, which is a good time to see the sunrise from an empty deck.

The crew live on ship time too, and on busy lines some crew members work through the change. That is one reason ships prefer to change on quieter nights and avoid changing clocks the night before a port, when disembarkation for tours starts early.

If you are joining a ship that has already made some of its changes, such as a partial segment of a longer voyage, ask at guest services which zone the ship is using. It may not match the country you are nearest to. For how this plays out on the crossings to Europe, see repositioning cruises to Europe.

Crossing the international date line on Pacific routes

On Pacific repositioning cruises, the ship also crosses the international date line. NOAA describes it as a line roughly following 180 degrees longitude, where the date changes. Crossing west, the calendar jumps forward a day; crossing east, it repeats a day.

• Westbound to Japan, Asia or Australia: a date disappears from your trip. The ship’s program simply skips it.
• Eastbound to North America: you live the same date twice, often with a small celebration on the “second” day.

The date change does not affect your body at all; only the hourly clock changes do. See repositioning cruises to Japan and Asia, Hawaii repositioning cruises and transpacific repositioning cruises for those routes, and Australia repositioning cruises for the southern Pacific.

Practical tips for ship time

• Set your phone to manual time and change it with the ship. At sea, phones can connect to a satellite or distant network and jump to the wrong time zone.
• Check reservations after each change. Spa appointments, specialty dinners and show times are all in ship time.
• Port times are local. All-aboard times in port use local time, which is normally the same as ship time. If the program says otherwise, follow the program.
• Book flights in local time. Your flight home runs on the local time of the airport. See flights home after a repositioning cruise.
• Use the extra hours. On a westbound crossing, the 25-hour days are a good time for the early gym session or sunrise on deck you would not otherwise get up for.

If jet lag worries you, book westbound. If you want to arrive in Europe rested, book eastbound and accept a few tired afternoons, knowing it is still the gentlest way to cross six time zones.