Why Are Big Ships Faster Than Small Ships?

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  • Опубліковано 23 гру 2024

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  • @FrontNine09
    @FrontNine09 2 роки тому +4641

    As a Naval Architect, I really wish I had access to these videos when I started my degree. Such a practical demonstration of the theoretical concepts.

    • @ReflectedMiles
      @ReflectedMiles 2 роки тому +36

      ....plus you would have understood how critical it is for large ships to be able to get up on plane if they're going to be any good, especially with efficiency plus speed together. If 590-ton craft can leave the ground supported by nothing more than a gas, what's the hold up? How can we expect planing not to be standard on large vessels? 😊

    • @krombopulosmichael6162
      @krombopulosmichael6162 2 роки тому +54

      @@ReflectedMiles sounds like you are suggesting hydrofoils. They are not efficient for larger ships. Please note my Naval Architectural degree is focused on plastic bathtub toys.

    • @EricGoesToShopClass
      @EricGoesToShopClass 2 роки тому +19

      As a docking tug captain, this is cool to see in exactly the opposite way 😂 Practical demonstration is all we get.
      Learning pressure zones on different hull forms is a very stressful experience.

    • @RobBCactive
      @RobBCactive 2 роки тому +5

      @@krombopulosmichael6162 No in the video plane speed was beyond the hump speed where the wave peak is at the bow and the trough at the stern, so the engines push uphill in addition to water resistance.

    • @krombopulosmichael6162
      @krombopulosmichael6162 2 роки тому +5

      @@RobBCactive most ships are not designed for plane speed though, according to the video. It does mention bulbous bows, which are becoming more common.

  • @davidsellon4580
    @davidsellon4580 2 роки тому +1951

    Thanks for the explanation. I've often wondered the same. Years ago, I was on a 42' private vessel crossing the Panama Canal. The Canal obviously has too much traffic to let a puny motoryacht take up an entire lock, so the Harbormaster put us in with a cargo vessel -- large, but sufficiently short to accomodate us both -- for each leg of the trip. On the way up, the big ship entered first, and we behind her. When we reached the lake elevation and that ship fired up her engines, her prop wash was so intense that the only thing keeping us from getting bashed into the sides of the lock were the six lines the Canal staff gave us (delivered by the famous "monkey fist") that held us tightly in the center. Still, all open beverages were immediately spilled. When she got underway and we followed, I was amazed at how quickly she put distance between the two vessels. In no time at all, we lost sight of her. Of course she made it across Gatun Lake in a fraction of the time it took us. The Canal staff knew this would happen, so they had previously scheduled us for a departure with a different vessel. This time, her length wasn't an issue, as they put us in ahead of her, and her bow literally covered the space we occupied. You don't truly get a sense of the scale of these beasts until you have looked straight up from the deck of your boat and seen nothing but metal above your head.

    • @andresmartinezramos7513
      @andresmartinezramos7513 2 роки тому +124

      The worlds most expensive parasol

    • @bnease007
      @bnease007 2 роки тому +124

      It’s hard to imagine taking a 42-foot vessel through the PC. It definitely would’ve been a fascinating and memorable adventure.

    • @davidsellon4580
      @davidsellon4580 2 роки тому +37

      @@bnease007, it sure was!

    • @robertu
      @robertu 2 роки тому +36

      @@bnease007 Taking any vessel through the first time is memorable and fascinating.

    • @AllAmericanGuyExpert
      @AllAmericanGuyExpert 2 роки тому +36

      I have a ship's bell from the Panama Canal. Weighs about 400 pounds.

  • @subnormality5854
    @subnormality5854 2 роки тому +1396

    I live 800 miles from an ocean, and yet I find your videos fascinating, including this one. Cheers!

    • @kevinmccaffrey3807
      @kevinmccaffrey3807 2 роки тому +11

      Now try living on the water and never taking a job or learn how to drive big boats and ships and watch these videos. I'm In my 30's and love these videos I wanna change my career. cheers

    • @TheClintonio
      @TheClintonio 2 роки тому +16

      Growing up on an island (and living on another) I've never felt the ocean not relevant. I wonder what it's like to live so far inland.

    • @ArsyanFirdaus
      @ArsyanFirdaus 2 роки тому +5

      I live 8 miles from an ocean, and yet still find this videos fascinating.

    • @Grimpy970
      @Grimpy970 2 роки тому +5

      Fuckin' SAME. I'm a landlubber who's lived in the desert my whole life

    • @dickJohnsonpeter
      @dickJohnsonpeter 2 роки тому +6

      I live 800 miles from land. I've never even seen the land before.

  • @cyberfutur5000
    @cyberfutur5000 2 роки тому +1160

    wow, I think this is the first time in my life, where someone used the term "wave length" and is actually talking about waves. (I am an audio engineer with a fable for physics, and I know, that those other waves are waves, too... but you know what I mean)
    And also, that was an utterly interesting video, thanks, I learned a lot^^

    • @jaybird1289
      @jaybird1289 2 роки тому +23

      same but for me light waves/ radiation funny how that feels!

    • @demacherius1
      @demacherius1 2 роки тому +17

      same here - electrical engineer

    • @barrypope4358
      @barrypope4358 2 роки тому +18

      Me Too..............I'm a Glove maker !

    • @prototypeinheritance515
      @prototypeinheritance515 2 роки тому +8

      Light and Audio-waves are "real" waves too!

    • @cyberfutur5000
      @cyberfutur5000 2 роки тому +6

      @@prototypeinheritance515 yea, that's exactly what I said🙃

  • @hawkeyeted
    @hawkeyeted 2 роки тому +252

    I spent 23 years on aircraft carriers. Being retired, I now work around a lot of Airforce dudes. None of them believe me when I tell them carriers are the fastest ships in the fleet.

    • @jpaugh64
      @jpaugh64 2 роки тому +20

      Yeah, that's not how it works in the video games, either! 😂

    • @timjohnun4297
      @timjohnun4297 2 роки тому +51

      People see that big wide flight deck and ignore the narrow beam at the water line. Probably understandable I guess

    • @jpaugh64
      @jpaugh64 2 роки тому +1

      @@timjohnun4297 😂

    • @jpaugh64
      @jpaugh64 2 роки тому +15

      @@hawkeyeted Why are you angry or surprised that video games are wrong?

    • @hawkeyeted
      @hawkeyeted 2 роки тому

      @@jpaugh64
      Why are you here chirping about stuff you know nothing about?

  • @scose
    @scose 2 роки тому +246

    Really appreciate that this video is pure information. no sponsorship, no Patreon pitch, no asking to subscribe

    • @b789har
      @b789har 2 роки тому +1

      Not for nothing but industrial accident recreation videos are interesting, informative and useful tools to prevent future avoidable accidents

    • @jorditakarbessy8547
      @jorditakarbessy8547 2 роки тому +13

      Is there something wrong about sponsorship, patreon pitch, and a very humble ask for subscibing?

    • @scose
      @scose 2 роки тому +6

      @@jorditakarbessy8547 they are not wrong but they get in the way of learning. So it's awesome when a youtuber can make ends meet without them

  • @mastasolo
    @mastasolo 2 роки тому +273

    Those jet engines on the ship are 100% what I would do If Kerbal had sea fairing vessels.

    • @hphp31416
      @hphp31416 2 роки тому +1

      Trent turbines are used to power both aircrafts and ships

    • @Digi20
      @Digi20 2 роки тому +9

      in fact there are many ship gas turbines that share most of their parts with airliner jet engines.

    • @mele2904
      @mele2904 2 роки тому

      Some US Navy vessels have turbine engines. Envy? LOL

    • @CynicalOldDwarf
      @CynicalOldDwarf 2 роки тому +5

      Have a look at Russia's Ekranoplan flying boats

    • @anonobot3333
      @anonobot3333 2 роки тому +1

      That’s what the fishing boat needs 😆

  • @capt.eissaeissa2769
    @capt.eissaeissa2769 2 роки тому +8

    As a retired Captain now involved in ship construction I find this presentation fantastic. Thanks for sharing, keep up the good work.

  • @toddkes5890
    @toddkes5890 2 роки тому +241

    I was thinking it was due to a ship 2* as long, wide, and tall having 4* the surface area (for drag), yet having an engine 8* as powerful. Didn't think about the wave interference. Good video

    • @ronblack7870
      @ronblack7870 2 роки тому +20

      i did too. thought it had to do with how a bigger engine takes more fuel but also the bigger ships caries exponentially more containers.

    • @sverkeren
      @sverkeren 2 роки тому +17

      ​@@ronblack7870 Not exponentially, but cubic more containers. Length*Width*Height.

    • @tinkerman9525
      @tinkerman9525 2 роки тому +5

      A boat twice as long is 8 times bigger. L x B x H.

    • @LoanwordEggcorn
      @LoanwordEggcorn 2 роки тому +17

      ​@@sverkeren A cube power is an exponent.

    • @dmitripogosian5084
      @dmitripogosian5084 2 роки тому +8

      This is what interesting is that hull speed is determined by the length of the ship, not area.

  • @steelbaron6343
    @steelbaron6343 2 роки тому +67

    4:40
    "But of course that isn't the hull story."
    Proceeds to give talk about the Hull design.
    Nice.

    • @dparag14
      @dparag14 2 роки тому

      And i thought it was just about momentum

  • @Tast_the_Confused
    @Tast_the_Confused 2 роки тому +37

    Informative, no nonsense, and very well structured for my layman mind to understand. You run a phenomenal channel and are a great teacher. Thank you!

  • @HikerBikerMoter
    @HikerBikerMoter 2 місяці тому +1

    1. the sheer wealth of knowledge these days
    2. the WAY its presented: video plus clear&concise video

  • @Lozzie74
    @Lozzie74 2 роки тому +8

    Beautifully explained. I’ve heard the waterline length rule touted for years and only recently learned it was due to a longer wavelength of bow and stern waves. You closed the loop for me, easily explaining that the wavelength was itself proportional to speed. Thank you!

    • @pwnmeisterage
      @pwnmeisterage 2 роки тому

      Assuming the ship is travelling against and into waves, of course.
      More often - for speed and efficiency - it'll travel with the waves whenever possible.
      Sometimes it'll have to travel across the waves, winds and currents don't always end at your planned destination.
      Sometimes the waters will be calm. Making the hull bulb counterproductive, if anything.

  • @bartbliek469
    @bartbliek469 2 роки тому +82

    I used to sail small boats as a teenager, and despite not knowing how any of this worked I remember intuitively feeling the phenomenon of hump speed and planing. Especially the boat 'falling' off the top of a wave, going from planing to hump speed, as a gust of wind dies off. Super facinating to learn how this actually works!

    • @dmitripogosian5084
      @dmitripogosian5084 2 роки тому

      And then you get on a keelboat, which cannot plane, and it does not matter whether the wind is 10 or 20 knots, you can't move any faster ....

    • @rydenkaye9735
      @rydenkaye9735 2 роки тому +5

      You can plane in keelboats my friend, you just haven’t been racing the right ones!

    • @dmitripogosian5084
      @dmitripogosian5084 2 роки тому +1

      @@rydenkaye9735 You need foils for that :)

    • @davidlabarr
      @davidlabarr 2 роки тому +3

      Same thing with adjusting the trim on a power boat. At a certain speed and perfect trim, you can just feel the resistance leave and the boat levels out.

    • @alberjumper
      @alberjumper Рік тому

      Exactly this

  • @awsalminen
    @awsalminen 2 роки тому +46

    Wow. Great video. I’m completely land locked but totally in love with the ocean. Just amazing information. Mind is blown right now

  • @Bruce-1956
    @Bruce-1956 2 роки тому +26

    I sailed on VLCCs in the '70s and their top speed was 15 knots. During the oil crisis we never sailed faster than 8 knots.

  • @calummcconnell7313
    @calummcconnell7313 2 роки тому +8

    also worth mentioning: the drag force is proportional to the cross sectional area of the ship. by the square-cube law, doubling the scale of a vessel will quadruple the drag, but allow 8 times the internal volume for engines to be put in. thus, if your engines take up the same amount of space, you'll have twice the power, and sqrt(2) times the speed

  • @borysnijinski331
    @borysnijinski331 2 роки тому +68

    I heard a story about a US navy carrier group deciding to have a drag race for amusement. As expected the smaller ships got the jump at the start, but it was not long before the carrier caught up and passed every other boat…much longer hull length.

    • @Digi20
      @Digi20 2 роки тому +19

      that must have been the most expensive (amount of oil burned apart from the nuclear carrier) drag race in history!

    • @jimskywaker4345
      @jimskywaker4345 2 роки тому +1

      @@Digi20 probably

    • @ziggyinc
      @ziggyinc 2 роки тому +1

      the Carrier always wins!

    • @ziggyinc
      @ziggyinc 2 роки тому +5

      @@Digi20 it happens every cruise.

    • @MarsStarcruiser
      @MarsStarcruiser 2 роки тому +3

      Well, I suppose they don’t call it plane speed for nothing

  • @jaquigreenlees
    @jaquigreenlees 2 роки тому +68

    You could easily expand this video with the hull shape aspect alone, ldl hulls are faster and lower fuel costs.
    a good example, an 85' loa motor yacht with a draft of 4 feet designed for displacement cruising. Top speed is 18 knots, cruising speed is 15 knots. 15 knots speed gives her 1,500 nm range on 1000 US gallons of diesel, 18 knots gets you 500 nm from the same quantity of fuel.
    These same factors are in play with the big cargo ships, yet most people can relate to being told if they slow down by 5 miles an hour they will travel 1000 miles further in their pleasure boat over it's cheaper to ship a 6 week trip than a 1 month trip for your overseas delivery..
    *ldl = low displacement length.

    • @Azettler1
      @Azettler1 2 роки тому +1

      500 nano-metres! Wow that's inefficient!

    • @jaquigreenlees
      @jaquigreenlees 2 роки тому +2

      @@Azettler1 nautical miles

    • @Azettler1
      @Azettler1 2 роки тому

      @@jaquigreenlees I knew what the acronym was for and was just bugging. I find it funny that we have two measures of distance that have the same unit label :)

  • @Vinemaple
    @Vinemaple 2 роки тому +2

    Hull shape!
    When I was in maritime school, this crazy old ex-Navy captain used to tell us, "whatever the question is, the answer's usually hull shape." And it's pretty close to correct, although he didn't like it much when the least-mature adult in the class tried to turn that into a running gag.
    That ex-captain never could get me to understand hull speed, though, and I never really understood the physics behind planing and the way a small craft's bow rises out of the water at hump speed. Never heard the term "hump speed" before. I've never been able to find this stuff in the American Seaman's Manual, either. But thanks to Casual Navigation, it all makes perfect sense. This is a gem of a video.
    And then we have the bonus of a big container ship getting up on a plane, and then being fitted with giant jet engines. That made me smile.

  • @thomashammel7633
    @thomashammel7633 2 роки тому +3

    Very happy about your new pace of publication, especially seeing that the quality of the videos didn't go down a notch! Good work!

  • @theVoyage
    @theVoyage 2 роки тому +279

    I've seen a boat running at "hump speed" before, a motor yacht. even to my untrained eye, it looked horribly inefficient, like the boat was trying to climb a hill.

    • @jimskywaker4345
      @jimskywaker4345 2 роки тому +26

      another term for that is transition wake, and yes it's very inefficiant

    • @HelloKittyFanMan.
      @HelloKittyFanMan. 2 роки тому +4

      In quotes? You don't think that's the real term?

    • @DemPilafian
      @DemPilafian 2 роки тому +7

      ​@@HelloKittyFanMan. Adding quotes like these usually implies fake, but it can also mean a special or unique phrase. Clearly it's the latter in this case.

    • @HelloKittyFanMan.
      @HelloKittyFanMan. 2 роки тому +3

      No, @@DemPilafian, it was _not_ clear, because if it was then I wouldn't have asked about it. Do you mean like... emphasis?
      Because if that's what you're trying to say, then you'd be wrong. Because if that is what you're trying to say, then my reply to that is that no, quotation marks are not emphasis marks, or they would be called "emphasis marks" alternately. That's not now, nor was it ever, their job. How anyone would've ever gotten taught that in some presumed "official" way completely baffles me! Emphasis is already handled by *boldness,* _italics

    • @DemPilafian
      @DemPilafian 2 роки тому +6

      @@HelloKittyFanMan. You should have put your entire 2 page reply inside of quotes.

  • @ThomasSteffien
    @ThomasSteffien 2 роки тому +142

    it maybe of interest: the bulbous bow works only at a limited range of speeds, because its wave has to interfere as designed with the normal bow-wave. Cargo ship hulls (including the bow-shape) are designed for a resonable range of cruising speed, to be fuel efficient. Intrestingly you can guess a ships speed by looking at its generated wave lenght at the hull. you only need to know how long the ship is, judge the length of the wave and use the formula depicted in the video to calculate the speed of the ship (through the water) ...

    • @dirkkarmel5209
      @dirkkarmel5209 2 роки тому +1

      Your explantion/guess,
      does not include water conditions.
      All vessels:
      would be much better with a nose bulb !
      -- Better for control of spin & steering;
      -- Keeping hull at a reasonable angle compared to the water surface.
      -- Better dispersing of the bow's wave.
      ******
      >> A Hydro-plane:
      -- can achieve higher speeds;
      -- has less danger of flipping over.
      ( compares to many automobiles that save gas, with 500lb -- 200 kg of cement inside the rear trunk ! )

    • @lochlanm8684
      @lochlanm8684 2 роки тому +4

      @@dirkkarmel5209 how would adding weight in your trunk improve efficiency??

    • @rydenkaye9735
      @rydenkaye9735 2 роки тому +9

      Dumbest comment I’ve ever read. Try strapping a bulb to any type of Planing hull and let me know how it goes

    • @happyambush1
      @happyambush1 2 роки тому

      Wouldn't it be way easier to just guess the speed than to guess the wave length AND guess the length of the hull to calculate the speed?

  • @CMDRSweeper
    @CMDRSweeper 2 роки тому +4

    Excellent video, I heard the term "Hull speed" but nobody had a good explanation as you put it here as to what happens.
    Keep up the good videos and knowledge spreading you do!

  • @runakovacs4759
    @runakovacs4759 2 роки тому +12

    I did not know the hull speed formula. It's nice to see it confirming my guesstimated speeds for my D&D ship's speed tho (130 ft 3 masted schooner at waterline, assumed her top speed to be around 12 knots. Which is less than hull speed, but considering wind and stuff it's within ballpark!)

  • @simonmakinson
    @simonmakinson 2 роки тому +1

    Brilliant as always. I just really enjoy how he doesn’t talk down to his audience. I learnt something watching this…thank you.

  • @8Mev
    @8Mev 2 роки тому +3

    As a random guy on the internet I have to say this is absolutely facinating so congrats to y'all naval engineers who choose an interesting major

  • @drewkelly6967
    @drewkelly6967 2 роки тому +2

    As an instructor of maritime topics, thank you for another video that makes me really think!

  • @jan-seli
    @jan-seli 2 роки тому +11

    I had assumed this was just going to be a fairly straightforward square-cube thing, where the drag on the ship scales with the surface area of the ship but the size of the engine it can hold scales more with the volume

    • @jpaugh64
      @jpaugh64 2 роки тому

      I would expect the engine size to scale with the economic utility of the cargo ship --- which would scale with it's volume.

  • @ethribin4188
    @ethribin4188 2 роки тому +9

    Overcoming the hump speed is mechanically the same as breaking the sound barrier.
    You wffectivly turn a wave into a straight line, saving tons of energy.
    But it needs tons of energy to overcome the hump/barrier first.
    And even then it needs more energy then any speed that doesnt approach thr hump/barrier.

    • @mele2904
      @mele2904 2 роки тому +3

      There are other ways to defeat the wave effects. Tuning shapes of leading and trailing edges to better suit lamellar flows back into the common plane on the trailing edge is the major factor. Shorter hulls can be made efficient at higher speeds but compromises are often made to achieve other desirable effects. This video however is a good beginner primer for this niche of fluid dynamics.

    • @jpaugh64
      @jpaugh64 2 роки тому

      I thought as much, and thought of the same analogy.
      "Needs more energy than any speed that doesn't approach the hump barrier." Every time you accelerate from zero, you're approaching the hump barrier. I know you're talking about it as a limit from Calculus, but how close to the hump barrier does it have to be for that factoid to lose veracity? 70%? 40%?
      Actually, Real Engineering shows a graph of drag vs mach number, and it clearly shows that mach 1 is a peak, and by mach 6, the drag is significantly lower.
      He was taking about rockets (which are designed to go faster than MACH 1), so I'm not sure if his graph was generally applicable to hurled objects or not.
      He was discussing the new startup with rockets whose "first stage" is a centrifugal slingshot. I can't remember the video title.

  • @spookynerd_jpg4223
    @spookynerd_jpg4223 2 роки тому +8

    Going into this, I thought it would be a matter of larger ships having larger, more powerful engines. That's a really interesting cause, though, and it shows just how much thought goes into every aspect of sailing.

    • @jpaugh64
      @jpaugh64 2 роки тому +2

      Well, obviously, larger (or underpowered) engines would have an effect. Also, does this rule work as well for pleasure and military ships, where finding the maximally efficient speed is not the most important criterion?
      The question at the beginning of his video is not well stated, so I'm not sure exactly what I learned.

    • @unthenner5519
      @unthenner5519 Рік тому

      Exactly! Thank you. Everyone else seems to be going along with this unclear premise without questioning it.

  • @el.blanco552
    @el.blanco552 2 роки тому

    I like how you answered the question again but this time with the context of everything we're talking about so the more literal explanation makes more sense. Great way to sum it up at the end of the video.

  • @mopsnuf
    @mopsnuf 2 роки тому +20

    This was extremely informative! One of my favourites of this channel so far. Very well explained and so interesting.

  • @bradleypeterson2208
    @bradleypeterson2208 2 роки тому +2

    I went fishing a lot growing up with my Dad in our 19ft jet boat, I’d always wondered why the boat pitched and accelerated differently before the boat got on step, and how it would fall off step. this makes perfect sense

  • @In_Our_Timeline
    @In_Our_Timeline 2 роки тому +53

    "If you want to build a ship, don't drum up people to collect wood and don't assign them tasks and work, but rather teach them to long for the endless immensity of the sea"
    --Antoine de Saint-Exupery

    • @jamesrodgers3132
      @jamesrodgers3132 2 роки тому +10

      All of which has nothing to do with the video.

    • @charliecharliewhiskey9403
      @charliecharliewhiskey9403 2 роки тому +6

      Probably also assign them tasks and work, or else *everyone* will go to collect wood without thinking about it and you'll deforest the surrounding area.

    • @duroxkilo
      @duroxkilo 2 роки тому +3

      @@jamesrodgers3132 that's like saying poetry has no practical applications :}

    • @jamesb2291
      @jamesb2291 2 роки тому +1

      @@jamesrodgers3132 I'm glad I'm not the only one who noticed.

    • @sclark9011
      @sclark9011 2 роки тому +1

      what the fuck is an ark ? Noah

  • @Lexoka
    @Lexoka 2 роки тому +2

    Very interesting, and very clear! In case you were wondering whether a longer, more detailed video on this topic would find its audience, know that you'd have at least one enthusiastic viewer.

  • @antnate578
    @antnate578 2 роки тому +6

    I love how these videos are extremely educational and are practically like having a real “ship” course.

  • @oliverwabwire2836
    @oliverwabwire2836 2 роки тому +1

    It's been short aeons.....till the term "wavelength" made this much sense to me! Thanks a bunch👍

  • @lewisdoherty7621
    @lewisdoherty7621 2 роки тому +8

    I assume the trough shown in the resistance/speed chart found after Hull Speed must have a name? I don't think it is called "Sweet Spot." This appears to be where the ratio of fuel consumed and time expended in transit would be best for ships.

  • @DaveSCameron
    @DaveSCameron 2 роки тому +1

    I really enjoy your work and efforts uploading these, not too technical and not too simplistic. 👍❤️🇬🇧

  • @Dave_Sisson
    @Dave_Sisson 2 роки тому +30

    Informative video. Could you please cover the large, high speed, passenger catamarans invented by Incat in 1990 and developments of that design such as the Austal trimaran you showed at the end of this video? I've always been amazed that craft over 100 metres long can travel at up to 50 knots and still be commercially succesful.

    • @calvinnyala9580
      @calvinnyala9580 2 роки тому +2

      Now that's tax money at work i would like to see

    • @tfhmobil
      @tfhmobil 2 роки тому +1

      Drag vs stability.
      Catamarans and Trimarans are very stable, even they hardly touch the water.

  • @dirkkarmel5209
    @dirkkarmel5209 2 роки тому +1

    Glad to see your method of reducing the condition, for the average person to understand.
    *********
    Beyond the hull waves, there are other factors that apply:
    -- Water surface conditons;
    -- Wind conditions;
    -- Water currents;
    -- Ship's acceleration/deceration.
    -- Angle against water of ship's bow,
    VS the ship's stern.
    In a smaller vessel:
    these quickly Add up !
    --- The vessel, quickly becomes unstable !
    --- Can easily flip over, in any direction !
    ( Bow going under the Stern,
    being least likely,
    frequently does occur during
    bad ocean conditions ! )
    In a larger vessel:
    -- These factors, are minor;
    -- Once up to speed, is very hard to change speeds or direction;
    -- Being longer & heavier, reduced dangers from waves;
    -- A skilled captain: can even use ocean waves, to their advantage.
    ( Using less engine power,
    to reach higher speeds. )

  • @naciremasti
    @naciremasti 2 роки тому +11

    Still awaiting that tugboat video.
    It'll be epic. Because tugboats are epic.

  • @thereal_morxy49
    @thereal_morxy49 2 роки тому +3

    Finally i understand why my uncle always told me it's better to go fast with the boat so it starts planing!

  • @Dovorans
    @Dovorans 2 роки тому +22

    I was under the impression that the hull speed was the last efficient speed (assuming a slippery hull) before the "wall" of resistance you get as you approach hump speed, due the destructive wave interference outlined in the video. So in the graph it would be found at the bottom of the little dip rather than at the hill before it.

    • @mele2904
      @mele2904 2 роки тому

      You can think of the hump speed as a kind of trailing vacuum effect as an analogy.

    • @jpaugh64
      @jpaugh64 2 роки тому +4

      There's a similar phenomenon with the speed of sound. Crossing it causes peak air resistance, but for a plane or rocket that's designed for it, going faster than MACH 1 decreases your air resistance the faster you go. So, for an aircraft, MACH 1 is the least efficient possible speed, compared to any other.

  • @lairdcummings9092
    @lairdcummings9092 2 роки тому

    Nice.
    I had some inkling of what is working here, but having it neatly encapsulated like this clarifies my thoughts and fills in the holes of my practical observations.

  • @hoodoo2001
    @hoodoo2001 2 роки тому +3

    Back around 1890 when they were building the first USS Texas battleship an argument ensued with the designer, the Bureau of Construction, and the actual builder. There were worries that the weight calculations of the ship had been in error and the builder suggested that the ship be made ten feet longer but the keel had already been laid (but could have been modified at extra cost). The builder said that the ship would have the added benefit of being faster as a result. However, the argument grew so heated about modifying the ship at this stage that the Bureau of Construction threatened to cancel the vessel due to the added cost...however the builder recalculated the weights and stated that while the lengthening could have added speed, the weights were not an issue so the project continued at the design and the Texas, although having an extremely long build time nonetheless was delivered on it's original budget to it's original design. As it turned out the USS Texas might have used an extra knot or two during the Battle of Santiago in 1898 but the Battle turned out well in any event for the United States.

  • @OneRandomMicrowave
    @OneRandomMicrowave 2 роки тому +7

    Perfect timing. I was bored so this is great

  • @barrackobama5470
    @barrackobama5470 2 роки тому

    Your videos have real peaked my interest into boats and sailing. I've never had any interest before this! I think I'm going to have a ask a friend with a boat to take me out so I can learn more!

  • @quillmaurer6563
    @quillmaurer6563 2 роки тому +6

    On a related note, how much of a large ship's drag is from wave drag vs. viscous drag against the ship's hull? I always got the impression wave drag is the dominant factor. Thinking of viscous drag would be another factor in favor of larger ships, at least in terms of efficiency. More volume (mass, cargo volume, displacement) per surface area, assuming a similar shape.

    • @Kieselmeister
      @Kieselmeister 2 роки тому

      Friction drag increases linearly with speed, wave drag increases with the square of speed.
      (Hull fouling from things like barnacles involves both, as the additional surface area of the protrusions increases friction, and each additional protrusion generates it's own wave.)

    • @rydenkaye9735
      @rydenkaye9735 2 роки тому

      Hull friction barely effects wake lol the waves generated by a individual barnacle are negligible compared to the tons of metal displacing water

    • @quillmaurer6563
      @quillmaurer6563 2 роки тому +1

      @@rydenkaye9735 Hull friction doesn't generate waves, it causes drag by another mechanism. Basically viscous friction between the ship and water causes a layer of water to be dragged along with the ship, which puts energy into the water and thus out of the ship, the engine needing to overcome this. Submarines have this, but don't have wave drag because they are too far from the surface to generate surface waves (hence, per displacement, submarines are actually more efficient, though with obvious other limitations and challenges).

    • @HulioPalas
      @HulioPalas 2 роки тому

      @@quillmaurer6563 i think a submarine generates waves as well, you just can't see them

  • @hagstruan1140
    @hagstruan1140 2 роки тому

    Every now and again the UA-cam recommendation algorithm comes up with a real gem. Subscribed.

  • @evancarpenter
    @evancarpenter 2 роки тому +3

    Wait, so the local min is between Hull speed and Hump speed, but what is the effect of the waves on the boat that makes it face less resistance? It seems like you only talked about the speeds individually, but maybe I missed something
    I loved the bit about the bulbous bow, I had no idea that’s what that was for!

    • @Jarrettmonty99
      @Jarrettmonty99 2 роки тому +1

      So I have no expertise or any knowledge about this subject, so I can't make any claims to the author of the video. BUT on doing a little research what I might ascertain is that the graph is shows applies to only a particular kind of boat (I can't find a similar graph anywhere, although it looks like this is not a hugely popularized field so I might just be bad at googling it). From what I've read, the right around the hull speed is going to be the true local minimum, although perhaps that's where things such as the bulbous bow come in, to stretch that minimum out before ascending the curve.
      It was an interesting topic to learn though, I'm electrical engineer so I missed out on all the fluid/mechanical goodies so I'm learning all the time on these topics! Let me know if you find out

  • @IIIIlII1IIIIIII
    @IIIIlII1IIIIIII 2 роки тому

    Hi I been watching your channel for quite a while now I’m a deckhand now🧑‍✈️

  • @man_on_wheelz
    @man_on_wheelz 2 роки тому +3

    Great, now you've got me visualizing a cargo ship planing the waves like a speed boat by force of several strapped on jet engines.

  • @Raggandrist
    @Raggandrist 2 роки тому +1

    I don’t even like ships, they scare me, but i’m such a geek that i can’t help being fascinated by all the technical elements and math involved.
    These video’s are amazing for people with a similarly geeky disposition as my own

    • @jpaugh64
      @jpaugh64 2 роки тому

      Things scare me. Mostly, my fears are real possibilities, however improbable. A wise man told me that voluntarily facing my fears was the best way to diminish them.

  • @TheErik249
    @TheErik249 2 роки тому +4

    20 yrs ago, My wife and I took a cruise from Vancouver BC to Hawaii on Princess cruise lines.
    The ship kept a steady spead of 24 knots for 2300 nautical miles to Nawiliwili on Kauai.
    When we docked, I got a chance to speak with a ship crew member while they were fueling.
    He said that they burned 800 tons of bunker oil.
    I told him that the trip was really smooth.
    He said that they cruise at that speed because its about physics and the hull design.
    He stated that the ship could go a little faster than that but, it would burn to much fuel.
    While we were underway ftom BC, we passed a smaller container ship under the Matson flag.
    Everything that YOU have stated here is CORRECT.
    Thank you sir!

  • @artificialowl3326
    @artificialowl3326 2 роки тому

    omg, I always wandered and never understood why boats had that feeling during some acceleration/deceleration process... thank you so much!

  • @ianprice6323
    @ianprice6323 2 роки тому +9

    The fastest ship ship I've ever been on was the USS Carl Vincent. We were going WAY faster than the 32 knots Wikipedia says it capable of. Seriously. WAY faster than that. It was mind blowing.
    Aircraft Carriers can move.

  • @Pax_Veritas
    @Pax_Veritas 2 роки тому

    All the info I needed about something I have no practical use for. Subscribed

  • @PeterKocic
    @PeterKocic 2 роки тому +3

    I guess something could be said about fuel consumption? I assume the smaller vessels choose to run at a more optimal hull speed because it makes sense financially. Unless, they have a customer willing to pay the extra price for express delivery speed?

  • @AustinPerdue
    @AustinPerdue 2 роки тому +1

    Always a treat. Keep making these!

  • @Jacob-W-5570
    @Jacob-W-5570 2 роки тому +16

    you might want to add, that to gain speed you need x times more power, that is a bigger reason why speeds are low.
    as for a 150 meter ship hull speed will be 29 knots but yet they sail 15. half of it.
    Also if you sail hull speed, with a wave top at bow and stern and a trough mid ships, you loose alot of stability. (not to mention bending moments that come into play at such situations)

    • @JarrodFrates
      @JarrodFrates 2 роки тому

      He covers that in another video: ua-cam.com/video/YPQY70z5uKE/v-deo.html

    • @fukkitful
      @fukkitful 2 роки тому

      Yes, the middle of your ship sagging can end very badly...

  • @rydenkaye9735
    @rydenkaye9735 2 роки тому +1

    My favorite example of this is the j class sailboats which have a design rule to limit waterline length but adapted by adding overhangs that enter the water and increase waterline when the boat heels over

  • @In_Our_Timeline
    @In_Our_Timeline 2 роки тому +22

    step one: get a big ship
    step two: apply for boat racing event
    step three: get rejected
    step four: say the a big ship is like a boat but bigger
    step five: they still reject you
    step six: give up

    • @nonna_sof5889
      @nonna_sof5889 2 роки тому +6

      step seven: try to run it anyway
      step eight: run aground because the course is to shallow

    • @matejlieskovsky9625
      @matejlieskovsky9625 2 роки тому +3

      step nine: dredge a deeper race course
      step ten: get smoked by a hydrofoil anyway

  • @JoeOvercoat
    @JoeOvercoat 2 роки тому

    Great video! I have been fascinated with this since I was just a lad learning about the great America’s Cup yachts from back in the day. And about the simpler sloop I served on. :)

  • @alveolate
    @alveolate 2 роки тому +3

    "A ship is just a hull displacing water."
    Dictionary of Casual Navigation

  • @ethzero
    @ethzero 2 роки тому

    Fascinating. Thanks random UA-cam recommend and the people that produced this excellent video!

  • @1898nc2
    @1898nc2 2 роки тому +19

    Me and my dad had almost identical boats the only difference was mine was 45’ where as his was 34’. For years how we couldn’t figure out why my boat was so much faster then his.

    • @jpaugh64
      @jpaugh64 2 роки тому +2

      To misquote Einstein, once you've eliminated the identical, the rest --- however improbable --- must be the cause. As a software developer, I've learned never to assume I know _anything_ about the system I'm trying to fix, no matter how much experience I have with it.

    • @vihreelinja4743
      @vihreelinja4743 2 роки тому

      but this is surely impossible to scale. they neeed to make a proportional 10x copy of a formula 1 boat and other speed boats to demonstrate the theory. and the power to weight/ size ratio must be equal.

  • @g.k.1669
    @g.k.1669 2 роки тому +1

    I live very close to the St. Clair river and frequently watch the Great Lakes freighters over 1000 feet in length and the salties (smaller ocean ships) down to just a few hundred feet as they travel up and down the river and into the Great Lakes. For years I have wondered about the wave pattern as some ships would create a massive wave at certain speeds while others moving at the same speed would produce hardly any waves, yet the same ship would then produce a huge wake at a slightly different speed. I just assumed that it was cargo weight that accounted for this. Usually I notice 3 wake patterns as one comes from the bow, another set from mid ship and the last from the stern. This answered a lot of questions for me. Thanks for the video.

  • @TheSwedishSalamander
    @TheSwedishSalamander 2 роки тому +3

    Now I want to see a cargo ship planing.

  • @michallacki9462
    @michallacki9462 2 роки тому

    As a mechanical engineering student I found this video super interesting! Love your content!

  • @martinbraden7110
    @martinbraden7110 2 роки тому +21

    Why is a longer boat faster than a smaller one? Because the front is closer to it's destination.

  • @N1ghthavvk
    @N1ghthavvk 2 роки тому +1

    I had to laugh out loud when I saw that massive commercial cargo vessel using the engines to start "climbing"!

  • @nou5440
    @nou5440 2 роки тому +3

    is hump speed how quickly a ship makes lifeboats?

  • @callunas
    @callunas 2 роки тому +1

    Thanks for making these purely informative videos. So cool when mathematical concepts appear so clearly like this!

  • @davewestner
    @davewestner 2 роки тому +3

    Does a similar thing apply to airplanes?
    For example, the 747 max speed is faster than the smaller 737.

    • @chuckaddison5134
      @chuckaddison5134 2 роки тому +1

      I would imagine that it would hold true, although the densities of the two fluids are substantually different.

    • @Dovorans
      @Dovorans 2 роки тому +1

      Kind of, in that increasing the size of the airplane increases the Reynolds number for a given speed, and things at higher reynolds numbers tend to have lightly lower drag coefficients. However, once you're at the scale of a small commuter plane drag from mach effects tends to be what limits your speed rather than the drag predicted for using the kind of incompressible flows the Reynolds number was modeled around.

    • @Titan604
      @Titan604 2 роки тому +1

      I expect it is more complicated due to the way air is compressible and the density also varies greatly. It is why jets cruise at high altitudes - high altitude = less dense air = higher speed and lower fuel consumption. There is a trade off, if the fuel used to climb to high altitude is more than what you save by being at that altitude, then there is no point, so shorter journeys may have a lower cruising height than longer ones as they don't spend enough time at high altitude to make it worth while. Concord was much smaller than either, but cruised at higher altitude.

    • @raypitts4880
      @raypitts4880 2 роки тому

      @@chuckaddison5134 same problem
      evan if water/air 800 times different.

  • @dfgiuy22
    @dfgiuy22 5 місяців тому

    So how do we get this channel to blow up enough to have the budget to get a commerical carrier to plane just using jet engines?
    Bro, thats such an awesome idea!

  • @Fanny-Fanny
    @Fanny-Fanny 2 роки тому +10

    The big'uns generally tend to have a faster 'hump speed', in my experience.

  • @jlethal4929
    @jlethal4929 2 роки тому +2

    What difference would fresh water make on hull speed? Does the lower density increase the wavelength, lowering speed? Is this why freighters on the American Great Lakes tend to be longer and narrower than a marine vessel of the same tonnage?

    • @trolleriffic
      @trolleriffic Рік тому

      Great Lakes freighters are that shape to be as big as possible for reasons of cost efficiency, while still fitting within the locks (Soo Locks?) they'll need to traverse. Apparently the rounded bow is designed to minimise wetted area and reduce drag, and its blunt shape isn't a problem at the low cruising speeds of these ships.

  • @cliffcampbell8827
    @cliffcampbell8827 2 роки тому +5

    Has anyone taken a closer look at ancient sailing ships specifically from around Greece, Rome...basically the Mediterranean area? I noticed that some of those ships had a bow with a 90° square to the natural water flow where a bulbous bow should be. Kind of like a stop sign of sorts, only under water and having 4 sides instead of 6. That big under water square bow seems counterproductive to me but maybe the ancients living in the bronze age knew something about fluid dynamics that are simply beyond me.

    • @cheveuxgraouh3821
      @cheveuxgraouh3821 2 роки тому +5

      It's a ram, it's not made simply to go through water, it needs to go through other ships too.

    • @cliffcampbell8827
      @cliffcampbell8827 2 роки тому

      @@cheveuxgraouh3821 Below the waterline?...and it was recessed a little behind the keel of the bow or figurehead (the ship I saw didn't have a figurehead). I think it was the Argus I was looking at but not sure.

    • @annasolovyeva1013
      @annasolovyeva1013 2 роки тому +4

      @@cliffcampbell8827 yes, so you make a hole in an other ship below the waterline and make it sink

  • @JasperB12
    @JasperB12 2 роки тому +1

    Keep up the great work! Love your voice! 😍

  • @mayankkumar3833
    @mayankkumar3833 2 роки тому +5

    Hump speed 🧐

  • @HannyDart
    @HannyDart 2 роки тому +1

    2:54 being an engineer from europe that one hurt.

  • @tamaslapsanszki8744
    @tamaslapsanszki8744 2 роки тому +8

    25 knots? Jesus, that's faster than many naval capital ships

    • @kathibaba7665
      @kathibaba7665 2 роки тому +3

      Not really. Naval vessels are usually designed for 25+ knots nowadays. US nuclear carriers can make 33 knots so a Carrier Battle Group is designed with ships that can keep up.

    • @tamaslapsanszki8744
      @tamaslapsanszki8744 2 роки тому +3

      @@kathibaba7665 those are top speeds, not cruise speeds. Of course top speeds are higher, especially for naval ships that usually have a fleet oiler/replenishment vessel nearby. For example the Kirov class battlecruisers have a cruising speed of 20 knots (nuclear), and Ticonderoga class cruisers have the same cruising speed (gas turbine)

  • @surfstarcc1
    @surfstarcc1 2 роки тому +1

    I've been boating my entire life and this just blew my mind.

  • @southaussiegarbo2054
    @southaussiegarbo2054 2 роки тому +3

    Strap on a few jet plane engines lol

  • @othernicksweretaken
    @othernicksweretaken 2 роки тому +1

    Naval architects in my country had the adage: _Länge läuft_
    (loosely translates to length runs)

  • @Negativity808
    @Negativity808 2 роки тому

    I'm not in any kind of naval anything yet I watch every video over time haha. I'm a pilot and I watch ship videos 😮

  • @beerjameswvu
    @beerjameswvu 2 роки тому

    The last ten seconds answered the question, and I'm so glad I stayed until then.

  • @Kennanjk
    @Kennanjk Рік тому

    I have learned much and will now calculate the optimal wake surf speed for my boat thank you.

  • @sleepib
    @sleepib 2 роки тому +1

    There's also the square cube law. Bigger ships have less surface area and cross section per unit volume, so if the same proportion of the ship is dedicated to engines, you have more power per unit of drag.

  • @someguardsman
    @someguardsman 2 роки тому

    Excellent video demonstrating theoretical concepts. Well done, wish I could like it twice!!

  • @timothysands5537
    @timothysands5537 2 роки тому +2

    Man, i had always wondered what that bulbous bow was for. Thank you for this video. Very clear explanation of constructive and destructive wave interference.
    That must mean that engineers design the length of the bulbous bow with the optimal speed in mind. Different speeds would require a different bulbous bow length, correct?

  • @aaronchown5008
    @aaronchown5008 2 роки тому

    Well there's an answer to a question I never had, I appreciate this new knowledge.

  • @adoreslaurel
    @adoreslaurel 2 роки тому

    I was on the QE a few short years ago and asked the Captain how much advantage the bulbous bow was, She said "This is an old ship [10 years?] and bulbous bows are not purely the answer,, she did not use those exact words, but the message was, that some other design feature was an improvement.

    • @danmarks9425
      @danmarks9425 2 роки тому

      Some cruise ships use stabilizing fins.

  • @f3tsch906
    @f3tsch906 2 роки тому +1

    I live in a landlocked country, but i really enjoyed this 👍

  • @hochulimarc2835
    @hochulimarc2835 2 роки тому

    I‘ve watched this video multiple times now, but I still don‘t get it. Where does the decrease of resistance between the hull and hump speed come from? ( 4:25 ) This isn‘t mentioned anywhere.

  • @Mastermachine100
    @Mastermachine100 2 роки тому

    I have no idea how I got to this video or why, but it was quite fascinating!

  • @benjamit2002
    @benjamit2002 2 роки тому

    great video, like saying a taller person has a longer stride than a shorter person, and thus walks faster

  • @peterdicker286
    @peterdicker286 2 роки тому

    I have been watching videos all morning with juvenile, naiive, and even childish narration (all Yanks) Thank you for providing some 'science for adults'. Cheers.
    Peter D (a proud Britt.)