Why Cruise Ships Are So Slow

So you’re having a race between a plane,
a car, and a ship. Now whoever decides to place their big bet
on the ship would have a bad day. Loser! And this is despite the fact that ships have
the most powerful engines! But why? We’re going to find out right now. Ships come in all shapes and sizes. From motorized dinghies to yachts; from glorious
looking white cruise ships to grim and bulky container ships and tankers. But they all share one quality: their engines
seem excessively powerful, yet they still can’t seem to output the speed you would’ve
expected from this kind of power. The reality is the exact opposite of the expectations:
a big liner can cross the Atlantic Ocean in a week, but a cargo ship would have to spend
more than two weeks to do the same thing. For a plane to go from an airport in Western
Europe to New York, for example, it would take only 8 hours. Some people might ask why we even use ships
if planes are so much faster. Well, here’s the catch: you won’t be able
to carry thousands of tons of weight by plane. The same goes for the number of passengers
– some ships can carry more than 5,000 passengers in one go! Try to fit that crowd in an airliner. Hey we can duct tape ‘em to the wings! As a further illustration, let’s take a
look at the supermassive ore carriers like Valemax – she’s a 1,188 ft long monstrosity
that can carry 400,000 tons of metal ore deadweight. That’s more than the weight of the entire
Empire State Building! Yet the ship will only go 17 mph, or 15 knots
as mariners would call it. That’s not even as fast as the running speed
of an Olympic track athlete. So in general, ships are going slow just because
they don’t need to go faster; their aim is set somewhere else completely. They sacrifice speed for better carrying capacity. Cars and planes may be faster, but even with
half of a cruise or cargo ship’s regular burden, cars wouldn’t even move, and the
plane wouldn’t be able to leave the ground. The engines of big ships are huge powerhouses
taking up entire rooms and swallowing tons of fuel each day like it’s a snack. ‘Emma Mærsk’ – the biggest cargo ship
in the world, capable of carrying up to 12,000 20ft metal containers, has an engine that
weighs 2,300 tons. When installed in the lower part of the ship,
it takes a three-story construction built around it for the crew to be able to provide
maintenance. It’s capable of producing more than 100,000
horsepower output of engine power. Transferred to an energy value, that would
be more than enough to power up a small city. “Uh, engine room, yeah we got some bad news. We need to step it up down there, the captain
wants to go water skiing.” This example may sound extreme, but it shows
just how much more powerful big ships are compared to cars or even planes. In contrast, ships have much more trouble
moving at all. When a plane flies, it needs to maintain enough
speed to stay up in the air, and it needs to avoid clouds when possible. You’ve probably experienced this nerve-racking
moment for yourself: when a plane goes through clouds it shakes quite a bit. This is because clouds are denser than air,
causing friction with the plane when it collides with the water vapor the clouds are made of. Unfortunately, ships have no choice but to
deal with the dense environment that often almost fully covers the ship’s hull. Water produces huge friction, slowing down
any movement significantly. Even something as fast as a bullet would slow
down and finally stop after just 100ft through the water. This is why every ship needs more power to
move at all. But brute force isn’t the only way ships
deal with the friction problem. Another big deal is the necessity to minimize
the area where the ship comes in direct contact with the water. And here come two big problems. It probably already occurred to you that not
all ships are huge liners, and some other ships can actually be quite fast. Yes, and those fast vessels are smaller. They go faster because they weigh less and
can glide right on the surface of the water using the thrust of their engines. Another trick smaller boats use is splitting
the hull into two parts. These boats and yachts are called catamarans. Their buoyancy isn’t as good as that of
a single-hull vessel, but they greatly reduce the need to touch the water with their smart
design. Getting back to the big stuff. A large ship is naturally submerged in the
water with a part of its hull up to the waterline. But this line shows only the predicted level
of water for the ship alone. If the ship is loaded with cargo, it’ll
be submerged deeper than that. And this means that it not only needs more
power to move its weight, but the water will make it even slower because there’ll be
more friction in play. But dealing with water is even trickier than
that. When a ship moves in the water, it displaces
a volume of water equal to the volume of its hull that’s submerged. This displaced water becomes waves that go
to the sides of the ship. These waves further increase the area of contact
with the water and therefore increases the friction. It may not seem like a big deal, but in reality,
it doesn’t only slow the ship down by as much as 40%, but also notably increases the
consumption of fuel. And that’s a big deal for transport companies. Good thing there was an ingenious solution
to this problem. All modern-day ships have a so-called bulbous
bow – the thing that’s submerged in the water right under the nose of the ship. These are exclusively designed for each type
of ship. Depending on the size, carrying capacity,
speed, and shape of the ship, the bulbous bow would also differ in size and shape. A bulbous bow is the first thing the water
meets when a ship is moving. Following its form, the water will try to
make a certain type of waves, but then it will encounter the main hull and also try
to produce waves of another type. When these two waves try to form at the same
time, they simply can’t, because they cancel one another out completely. This is why modern ships don’t produce waves
around them anymore, and their speed is no longer so heavily affected by them. You can see for yourself – the water around
modern big ships is relatively flat. If the shape of a bulbous bow is even slightly
deformed, it won’t be effective at all, and waves will appear once again. But hey, if you want some speed, that doesn’t
mean you have to forget about ships and boats entirely! Even cruise ships these days can be fast. HSC Francisco is one ship just like that. It combines the size of a cruise ship, capable
of carrying 1,000 passengers in luxury, and the design of a catamaran. Each side of the hull is fitted with wave-piercers
to further improve the speed of the ship. And if it wasn’t already enough, it’s
powered by a gas turbine engine that drives two water-jets. These jets shoot powerful streams of water
and propel the ship forward. Each jet stream shoots 6,300 gallons of water
every second and provides enough thrust to speed the ship up to an unbelievable 58 knots,
or 67 mph. For such a huge vessel, this speed is almost
unheard of. And that’s not the fastest you can go on
the water of course. WP-18 Special Forces Interceptor is a boat
you’d expect to see in a sci-fi movie. But it’s real, and it’s literally cutting
edge design is specially developed to cut through waves at the extremely high speed
of 65 knots, or 74 mph. The main purpose of this vessel is, as you
can guess, to intercept ships that are trying to escape. Like, for example, pirates or other criminals. And let’s just say, it’s not even worth
trying to shake this speed demon from your trail. A rush for top speeds was, and always will
be, in people’s minds no matter what. This gave birth to another incredible vessel
– The Mystic Powerboats C5000. A 50ft long catamaran boat that’s so fast,
it needed a cockpit to protect the driver. The max speed achieved in this boat is mind-blowing
250 mph. If you want to go even faster, I have bad
news for you: the sea won’t let you, because it won’t be calm enough. Speeds higher than that would be too dangerous. For a boat that goes this fast, the waves
would be as hard as concrete. Going into one of them would launch the boat
into the air like a trampoline and the next wave would simply crush it. So it seems like about 300 mph is the natural
speed limit of the sea itself. Hey, if you learned something new today, then
you’ll enjoy. Just click to the left or right, and stay
on the Bright Side of life!

100 thoughts on “Why Cruise Ships Are So Slow

  1. Brightside can't even get simple scientific facts right. Planes don't experience turbulance in clouds because they are denser than air. How can clouds be denser than air, if they were they'd just sink, right? What utter rubbish and demonstates a complete lack of even the most basic scientific understanding. If planes do experience turbulance within clouds it's due to the convective updraughts that are causing the clouds to form in the first place.

  2. Slower is cheaper, they are paying by the day, not the mile. Go 10 miles off shore, drive around in circles for 6 days, go back. The idiots would be just as happy.

  3. If you guys aren't sure what is a cruise ship, can you google it b4 you give this title?!
    Here i have done it for you :
    A cruise ship is a passenger ship used for pleasure voyages on which the voyage itself, the ship's amenities, and usually the different destinations (ports of call) along the way each form part of the passengers' experience.

    This clip is not talking about cruise ship at all!
    And you gave a very bad illustration of ship vs airplane.
    (If one plane can't carry so many people, then get more plane to carry!)
    Most of the time, It's not airplane couldn't carry heavy staff, its because airfreight is more expensive then sea-freight. (not to mentioned those extremely big and heavy staff)

    Do your research well because you post. Your millions subscribers don't come easily.
    Don't take us for granted and mislead the public.

  4. Actually you are right cars won’t be able to move but semi trucks will when caring a container when a cargo ship goes down a little bit cause the load it’s called draft

  5. Free lightroom Presets with DNG file are available in my YouTube Channel… Hope you'll visit and find it useful too 😊

  6. You people have some good videos but sometimes you run out of material and explain things only retards need explaining.

  7. Why are cruise ship are slow? My answer is: Coz they are heavy and they carry some people or container and the engine is more weight and the water is a "REALLY HARD TO MOVE PLACE" and bcuz its really slow its merged in to the water deep and the propeller is just 3,4, or 5 Thats my answer!

  8. I was confused at first, but let me see if I’ve got this right. Ships are big and carry a lot but move slowly. Planes are smaller and carry less but go faster. Is that right? Doh, maybe I’d better watch it again and try to get this all figured out.

  9. The screws on a ship are most efficient at 800-1200. RPM. Any more causes too much cavitation, and that causes wear on the prop.

  10. Regarding displacement ships, the engine (s) in today's ships might be big and powerful, but relative to the mass of the object being driving, they are small, Old liners, like the France, the Queens, United States, and Normandy, had more power, higher speed, and multiple propellers–usually 4, not 2 or 1.

  11. I sometimes wonder where you people get your information from. In numerous cases it can be either erroneous, just totally wrong or flawed.
    Here is another blinding example of ignorance. Statement made “the waterline (with painted anti fouling goes under the water when the ship is fully Leiden. WRONG, the antifouling should not be covered as it’s there for a purpose. The are marks painted on the hull called the plimsoll line. This is where the ship when she is laden will come to rest. And not any higher.

    I like your channel , but I only ever take it with a grain of sand now as I have found far too many holes in the information you impart to have any faith in what you are imparting. Sorry fellas.

    Oh yes, the matter of the cruise ship. It’s not in a hurry as it is not a passenger ship sailing between two or more ports as a means of ferrying people to and from ports. Where as a cruise ship is all about the experience not just the getting to the other end as quick as possible. Recently I had reason to lookup the whereabouts on the ship Voyager of the seas. She only had to travel 42 nm, and she had 9 hrs to get there. Will calculations (not taking in to account currents) she could sail at 4.7 nm and arrive on time. She slipped her lines at approximately 9pm and was due in at 6am the following morning. She was sailing between the port of Kalang and Malacca in the malaccian strait. She has a service speed of 22 nm/hr. So if she was to do her service speed the journey would have taken less then 2hrs. So, the reason for cruise ships being slower is it’s the EXPERIENCE that passengers are paying for not SPEED.

  12. I’m a small YouTuber on the road to a million subs and subs and I will be gifting 🎁 my next 20 loyal subscribers by subbing to them 💖

  13. Cruise ships aren’t slow they look slow for a few minutes but I crossed half the world in 2 nights so not really that slow

  14. Is this a question that even needs to be asked?!? Might just be me but surely it’s obvious the Oasis of the Seas won’t be making New York to Southampton in 4 hours any time soon. What a ridiculous video. Didn’t even bother watching the first 5 seconds.

  15. 3:21 "Planes . . . need to avoid clouds, when possible." Wow! I flew as a professional pilot – military, airline, and civilian contractor – for well over 40 years, and nobody ever mentioned that. And it is amazing that in 29,000 hours of piloting I never noticed a plane shaking from colliding with water vapor. The things we can learn from watching YouTube !
    Actually what Bright Side, and their viewers, should know is that the turbulence sometimes associated with certain cloud types is about differing temperatures and resulting vertical air movement. There is water vapor in the atmosphere whether it is visible as clouds or not. That, too, is about temperature, not density.

  16. Speed is better for fast transportation
    1200kph is the best speed for airplanes
    300mph is the natural limit of speed in a sea
    300,000kph is the speed limit in the vaccum
    300,000.001kph will make a black hole
    While capacity is better for more cargo and passangers
    2tons in a small boat

    Speed is inversely proportional to capacity

    However, That can be broken

    Design is the answer


  17. A lot of misinformation and half truths. Ships are almost always displacement vessels with the weight being borne by the water displaced, this limits their speed to a function of the hull length (f x sq root of L), speedboats are planning vessels with the weight carried as a lifting force on their hull. Ships generally have about 5 hp or less per ton of weight, speedboats generally need about 100 hp or more per ton of weight. All modern ships use heavy diesel engines that are highly fuel efficient, speedboats generally use light gasoline engines that are not too efficient. The cat cruise ship described has gas turbines, very inefficient at sea level, operate much better at 30,000 ft or higher like in an aeroplane. Ships use less fuel per ton/mile of cargo movement than any other form of transportation. As for airplanes, the cargo version of the 747, the most efficient air freighter probably has more take off horse power than that giant container ship, the 747 can carry about 100 tons of cargo vs the 100,000 tons for the ship and will burn about 100 tons of fuel crossing the ocean that it can do in about 8 hours, the ship will take 8 days burning about 1000 tons of fuel, ten times the fuel burn with 1000 times the amount of cargo making the ship 100 times more fuel efficient. Most cruise ships can do between 20 and 25 knots if they are in a hurry, but they are cruising, what's the rush. Ocean liners like the Cunard Queens can go between 28 and 35 knots and they have a schedule to meet. All of these vessels are diesel powered. Remember that passenger ships use a lot of power to generate electricity to keep the lights on, the air conditioners running, and the slot machines in the casino humming. Most newer cruise ships are diesel/electric with engine generators powering the electric motors that propel the ship. The word 'ship' historically described a certain type of sailing vessel, one with three masts and square sails, other sailing vessels might be a schooner with two masts or more and fore and aft sails, or a sloop with one mast and fore and aft sails, a bark (barkentine) would be like a schooner only with square sails on the foremast, example the Coast Guard Academy's training bark, the Eagle. The Eagle has reportedly achieved speeds of over 20 knots with the right winds. Who said sailboats are slow?

  18. maybe because they weigh hundreds of thousands of pounds and if you haven't noticed it isn't all to easy to push a block of steel through water

  19. cruise ships are not slow at all cruise at between 18 and 20 mph think about a 12 story hotel moving that fast ha ha ha

Leave a Reply
