WHY DON'T CRUISE SHIPS TIP OVER? | An introduction to ship stability

[@seaprofexecutiveeducation3750]

I am a retired UK Class 1 Master Mariner and I like this video. It's not meant for mariners as a teaching aid. It's meant for ordinary people and it uses non specialist language. Great stuff and I am going to recommend it to my MSc Maritime Studies class in Singapore. Some of them are mariners. Most of them are not and this video will be ideal learning for them. Well done sir!!

[@CasualNavigation]

Thanks for the comments SeaProf. I know there are plenty of technical videos for mariners to learn from, so I wanted to create something for everyone else. I am pleased that the video has come across as intended and will be useful to your class.

[@sunilmahapatra6897]

I am a mechanical design engineer Sir during the 1st case that means When tilting occurs due to any force.. definitely some parts of ship from lower area(under water) will come to upward from water, so CG must change from its mean line towards the max weight(max surface area apparently) but in this video ships CG is not changing from its mean position at all. Is that possible ? Sir please explain me ....

[@CasualNavigation]

Thanks Sunil. The CG is the average position of all the masses onboard. Unless any of the masses within the vessel move, the CG cannot move. Applying an outside force does not affect the CG. Only adding or moving mass within the vessel can change the CG.

[@SportSoulLife]

The Casual Navigator Well you have to count in slushing to the centre of gravity too, but on passenger ships that usually doesnt change too much. Overall, this is a great video to explain in a nutshell to non mariners how it works, and a great video for maritime students to learn the very basics before jumping into further forces and graphs.

[@CasualNavigation]

Thanks SportSoulLife. That was the aim for this video so I am pleased it has come across that way.

[@jorisd6584]

I love how you just shifted the centre of gravity of a cruise ship with a 10kg weight

[@CasualNavigation]

In reality, yes, a 10kg weight would make no noticeable difference. It did suffice for the diagram though

[@jeddominic2931]

Its just an Example .. Lol

[@08566581846]

Must be a toy ship

[@Lucius_Chiaraviglio]

That said, this example ship doesn't seem to have much safety margin to compensate for things like big waves or ice/hail/sleet/snow accumulating on the upper decks (especially if that stuff is coming preferentially from one side).

[@jorgensenmj]

Now if we can just apply this cruise ship technology to all ships and boats.

[@victoriajames586]

On a recent Cruise in the North Atlantic in winter I thought it was going to go over. The only person who thought we were safe was the captain who just laughed and said "Disney's rides only give you this for a couple of minutes I have given you a whole week"

[@CasualNavigation]

It is true that the everyone aboard will feel uncomfortable a long time before the ship is actually unsafe.

[@cerebralm]

I used to be terrified of canoes cause they feel so tippy. One day my dad said "son, lets both go put life jackets on, push the canoe out from the dock a bit and purposefully tip it over". Okay. So we did. And once I did it for myself i realized how HARD it is to tip a canoe, and they don't scare me anymore at all. :D

[@shed7614]

Disney cruises also give you child molestation, people being thrown overboard, stabbings, theft and plenty more without even a policeman on board. Plus the added bonus of crappy characters that nobody really wants as an adult. I suffered through Disney as a child and didn't realise that the crap continues today. I think I would rather do time in a padded cell.

[@JamesTTierce]

@@shed7614 wait... were you molestedereded on a cruise ship?

[@tinycockjock1967]

james braselton You okay there mate?

[@Snudedude]

Sweden's most popular tourist attraction is the warship Vasa, built in 1628. Unfortunately the constructors had not watched your video.

[@daveroberts6884]

Lucky for Sweden today but a disaster in its day in the sun.

[@jorgensenmj]

A high center of gravity with a high structure above the waterline and 2 levels of cannons. A shallow hold with not enough ballast. A short light keel. The problems were correctable...but the king was impatient.

[@andvil01]

@@jorgensenmj and lose cannons high up taking the center of gravity outside the center of bouancy.

[@raymondleggs5508]

Or the builders of the German ocean liner the SS Emperator/ RMS Berengaria

[@OnboardG1]

The lucky buggers went over in shallow water at least. Mary Rose wasn’t that lucky.

[@ThePolecatProcess]

Because if they did no one would ride them

[@FreedomTalkMedia]

Aricstylegaming lol,

[@chado3000]

Like my sister.

[@tommieduhswamy6860]

@@chado3000 has nothing to do with spelling...Which is the correct terminology?... is what I'm asking

[@brokeindio5072]

It's big brain time

[@gormauslander]

Well you saved me 5 minutes of my time

[@66Flux]

The fundamental idea is: The center of buoyancy for an object is the center of mass for the fluid it displaces.

[@CasualNavigation]

Thanks Voitto. I hadn't thought of it like that before, but your way does explain centre of buoyancy very well.

[@Tina06019]

That is a perfect description of center of bouyancy, I think. I know doodle-squat about ships, but I understand physics.

[@GregConquest]

Yeah, I think that's right, but it is also the geometrical center of the cross-section. If you could print on cardstock the cross-section of the hull at the waterline and below, then the center of that would be where you could balance it on the point of a pin/pen.

[@klopfgeist898]

@@GregConquest You're both right. As the displaced water has a constant density the geometrical center of the cross section is also the center of gravity. If for example the density of the water would change with increasing depth Voitto Kotiahos definition would still be correct though.

[@TamimProduction]

It is, literally, Archimedes' principle: "A body at rest in a fluid is acted upon by a force pushing upward called the buoyant force, which is equal to the weight of the fluid that the body displaces. If the body is completely submerged, the volume of fluid displaced is equal to the volume of the body."

[@malacki6554]

We were just taught in school that ships don’t sink because they’re less dense than water,we never learnt all this extra stuff

[@jorgensenmj]

Why ships float. Why ships don't tip over. Two different subjects.

[@Gwynbleiddsanity]

@@jorgensenmj it explained both

[@sirankleknocker3122]

“Ships don’t sink” Costa Concordia, the most recent sunken ship: “And that, I refuse to believe.”

[@Vikas_Kumar_Singh]

@@sirankleknocker3122 it had many reason for sinking and it also didn't sank it was only half sank

[@stenbak88]

There's a wizard on every ship

[@Hyperion9700]

Hey Casual Navigator ! I'm deeply afraid of ships and the ocean and with your videos now in June 2020 I am learning about my fear and how irrational it is because your videos explain how ships work and now that I understand that Im not as afraid to board a boat

[@HANKSANDY69420]

Epic a seafarer teaches a landlubber to be fearless

[@ErnestJay88]

That's why swimming pool on cruise ship always on the middle doesn't matter it's on aft or fwd deck, never on the sides, because water is heavy and it also add center of gravity for the ship.

[@BearLamb123]

Ernest Jay A factor that is at least as important as the weight of the water itself, is the effect of free liquid surface. Any slight tilt a ship experiences allows the water in the pool to move in the direction the ship is tilting, which shifts the center of gravity of the ship in the same direction- intensifying the tilt, effectively a dangerous positive feedback loop. This is the reason pretty much all swimming pools on ships are much longer than they are wide, as a greater width greatly increases the aforementioned effect.

[@EmdrGreg]

Wait... the pool doesn't 'add' to the center of gravity; the center of gravity is a single point. A pool higher up on a ship will RAISE the center of gravity, which I would guess the designers have to be extremely careful about. The idea in the video is that the floating ship will tend to be more stable the lower the center of gravity is.

[@andvil01]

@@BearLamb123 yes, like water on the car deck of a ferry. M/S Estonia back in 1994.

[@simonreeves3229]

Good point , but it doesnt 'add' to the centre of gravity/bouyancy . The simple fact is that the pool is in the middle due to obvious reasons yes but the centre of gravity was there and the pool may tip it out if sync

[@МихайлоСєльський]

Wow, these 10 kilos were so intense))

[@mariebcfhs9491]

maybe this is just a ship model 😂😂😂

[@brokeindio5072]

10 kilos of nails

[@madrx2]

*Francesco Schettino has left the chat*

[@pgtmr2713]

Going to guess that 's an Italian cruise ship captain.

[@RyanTheRandom]

madrx2 *CostaConcordia.exe has stopped working*

[@mirzaahmed6589]

@@pgtmr2713 Costa Concordia

[@pgtmr2713]

@@mirzaahmed6589 Yep

[@buseini]

madrx2 and was last seen in a cafe on shore ordering a Peroni.

[@RobertSeviour1]

The quality of this video tutorial has been recognised by many of its viewers, but one aspect has not been commented on so far: there is no 'music' track added behind the speaker. I am so happy about that because many other YT videos have intrusive, and very often highly repetitive, 'musical' phrases added; they distract and irritate me enormously. So well done and thanks.

[@livinginvancouverbc2247]

On a topic of such gravity as ships capsizing, you kept the mood... ...buoyant.

[@harryjoyce9470]

This deserves many more likes

[@ianpatterson3471]

I'm afraid that this landlubber still can't grasp the concept of buoyancy, BUT I must say that was probably the best educational video I've ever seen. You have a lovely voice sir, you take sensible pauses, and you're perfectly in sync with your excellent diagrams! Thank you. :-)

[@CasualNavigation]

Thanks Ian. I appreciate the remarks and am glad you liked the video.

[@amediumlysaltedpearl4325]

Ian Patterson *_landlubber_*

[@MTieleman]

Buoyancy = the weight of the water beig displaced. When an object weighs 2 kg, but pushes aside 3kg of water, the object is positively buoyant and will go up. When an object weighs 2 kg, but pushes aside 1 kg of water, the object is negatively buoyant and will sink. When an object weighs 2 kg and pushes aside 2 kg of water the object is neutrally buoyant and will float at exactly the same depth it is at. Just like a diver would. For a ship that means it will have a certain draft where the ship weighs as much as the amount of water it displaces. If the ship then loads more weight, it will go a little deeper in the water, and if it unloads, it will rise a bit more out of the water. The buoyant upward force and the downward gravity force are equal. This video is more about stability though. That point of gravity from the ship and buoyancy from the water create a torque/moment between each other. If the weight on the ship stays the same, the point of gravity stays the same, but the point of buoyancy will change when the ship rolls because the distribution of the volume of water changes. Torque=force*arm. Force stays the same, and when the ship heels the (horizontal) arm increases, until the torque between downward force(gravity) and upward force (buoyancy) is the same as the torque of the disturbing element (wind or wave).

[@MTieleman]

Ps. It is a nice video. Doesn't cover metacentric height, but still, really nicely done.

[@CasualNavigation]

Thanks M Tieleman. I did intentionally leave out metacentric height as it was a little too detailed for this video. I will try and cover it in another video though.

[@keegan773]

They don't fall over because all the fat people are placed in the cabins on the lower decks. If you eat too much during the voyage you will find yourself being reallocated to a lower deck cabin.

[@dgamerprince9794]

keegan773. Wow racist lately

[@keegan773]

Kyle Wickett I might be "Plumpist" can't see how that relates to "Racist".

[@keegan773]

Myles Lee Did you have to move cabins?

[@murphyspattaya]

Lol

[@marvinblankinchip2535]

keegan773 ... Just goes to prove how stupid race baiters can be.

[@ShadowGundam1989]

2:11 That ship Design looks like a Sippy cup

[@PickSixCentral]

Lol

[@jimmywibins1860]

The boat in the intro is the Queen Mary 2 from the Cunard line and is not a cruise ship. It's an ocean liner (The only one left) like the titanic. It has a a deeper hull to help stabilise during Atlantic crossings.

[@anormalcommentor9452]

SHIPPPPPPPPP Also she's half ocean liner but mainly does cruises so it's fair to call her both Ocean Liner and both Cruise Ship

[@jimmywibins1860]

@@anormalcommentor9452 My main point is that she has a deeper draft than cruise ships and this was a video on how cruise ships stay stable. But I admit the principle is still the same.

[@bojack40]

Thanks. I’m completely unschooled in such matters, and I’m finding these videos really interesting and helpful.

[@fire_n_ice1984]

Love your channel. Precisely explained, easy to understand, and no unnecessary/annoying music, sound, voice or topics. Well done 👏 : )

[@monkeycarz]

This is really informative and well presented. It would be cool though to see some examples of what COULD cause it to tip over.

[@CasualNavigation]

Thanks monkeycarz. I'll add that to my video ideas and look to do a whole video with a few examples.

[@jonathoncary4109]

Very very good.Been living on a boat for 14 years.I have learnt something-at last!

[@CasualNavigation]

Thanks Jonathon, glad it helped.

[@robertking3130]

There was that terrible movie "The Poseidon Adventure" where the ship turned turtle and the liner that turned turtle in Hong Kong harbour.

[@fhuber7507]

The arcs of the CG vs the CB are what controls how far over the ship can roll and still self-right All you have to do to make a ship roll on over is to exceed the maximum self righting list angle AT ALL and the ship is doomed if you don't have some other force acting to bring it upright. Every ship design has an unladen maximum "list" before capsizing and that is easy to plot, because you know where everything is on the unladen (no passengers, cargo or fuel) CG of the ship will be. Add cargo, fuel , consumables (food stores, etc) and the passengers, luggage and cargo and calculating the max list angle can be obscenely complex (especially when all the passengers decide to go the to port rail to watch whales at the same time) To deal with moving cargo (people) and to make the ride smoother (less vomiting by the moving cargo) modern cruse ships use gyro stabilizers. That works as long as the gyros are big enough and they have power. With CG well above CB, it doesn't take a lot of list angle to go past the point where the ship can't self-right. Some ships can't survive 10 degrees without the gyros. (this is stupid)

[@arnoldkokonya]

Am a software engineer. I don't know a lot about ships but this video explained so much step by step, that I was able to understand a lot about ships. Wow. Just amazing.

[@CasualNavigation]

Thanks Arnold. Glad you found it useful

[@jimbronson687]

Great Video big guy. I did smash the like button. I am an engineer and you explain science and physics and engineering very well to the non science minded and or the interested who have a natural ability to grasp concepts but have not learned by experiment experiance or someone like yourself. You have a great teaching ability and that is rare, Thank you.

[@CasualNavigation]

Thanks Jim. I appreciate your kind words, and am pleased that you liked the content.

[@jigzmalakas6253]

Humans are so intelligent. I love you all humans reading this. You're such a great part of this world.

[@flysfck]

Overwatch😎

[@muuundotarde7914]

The Reaper and then you remeber that humanity is the single most violent species ever to walk the earth. Just beacuse everyone is scared of going to jail, and therefor behaves, does not mean we stopped being humans. Yeah humans suck hard, if they are not kept under complete controll, they just start raping and killing eachother for funn. Refrences: human history..

[@jigzmalakas6253]

Babies are born not knowing bad things ryt?. Humans came violent or bad/evil because or depends on their environment.

[@muuundotarde7914]

The Reaper oh dear lord, someone has not been. Good boi in school, i wonder what factors during your childhood made you unable to understand words. But really tho, how many times were you kicked in the head l

[@marcelrodriguez2067]

Most are dumb as hell and useless though.

[@michaelbuntine362]

I actually wish you was my teacher when I was in school.... I just learned so much from you... And I understood the lot...and it's so interesting.. THANK YOU 👌👌

[@RobG001]

Clear, concise, articulate and informative, great stuff...

[@CasualNavigation]

Thanks for the comments Rob!

[@2011arish]

Ok

[@janwinter2373]

I’ve just begun my SQA Level 3 course in maritime studies hoping to become a deck officer in the future in the merchant navy. I’d love to see more videos on the physics involved in ships and would be very grateful if you made more like this.

[@CasualNavigation]

Thanks Jan. More are coming each week. I enjoy the physics too, so more like that will definitely be coming.

[@TheGraemeEvans]

The key part that isn't described, which is that the shape the hull is designed so that a tilt causes the centre of boyency to move, it doesn't happen by chance. If the hull was semi circular the ship would fall over unless the c of g was lower. So it's the shape of the hull that allows this top heavy object to stay upright.

This. Now I understand why a rowboat is so hard to enter from the side - it's not just the size, but shape.

[@sirankleknocker3122]

“Cruise ships” *shows the last ocean liner in operation in the thumbnail*

[@tutracrafty]

The difference is arbitrary and the forces in use are the same.

[@colinmccarthy7921]

I did a five year indentured apprenticeship in marine engineering + college day-release.I worked on the Queen Mary,Queen Elizabeth 1 and many other large liners.Some of these large liners had stabilisers on each side of them.If the weather was rough,the stabilisers were extended into water. This stabilised the liner. My apprenticeship,covered Fitting Shop,Fitting on Liners,Machine Work and the Drawing Office.This also included Dry-Dock Work. I enjoyed watching the video.

[@jaimeduncan6167]

Very elegant explanation , the use of graphics simplify understanding:. It’s an elementary problem, but one that Gelo people think in terms of fundamentals.

[@CasualNavigation]

Thanks Jamie. I appreciate the remarks.

[@buddyclem7328]

Please define Gelo, unless that was a typo. My spell check corrected it as help, and helps makes sense.

[@bd8026]

This video was buoyant, informative, and the center of interest.

[@IntricateUniverse25]

I have always wondered this. The thought of all that ship above water and so little below always unsettled me. Obviously those multi million dollae machines are well engineered but it still triggers my brain to think that it could easily tip over.

[@HANKSANDY69420]

"Dollae"

[@jasonreed7522]

Your brain isn't exactly wrong, the tilt/roll window in which a ship wants to return to 0° (vertical) is much smaller than the tilt window where the ship wants to lay down on its side or even fully capsize. Fortunately ships usually have a surprising generous range in which they can roll without loss of stability. (And some coastguard boats can actually make a full revolution and be fine, but the passengers may want to wear a seatbelt for that)

[@carlmanvers5009]

As long as the center of gravity and the center of buoyancy can line up, the ship will right itself. Seems strange I know, but physics can be like that. Load calculations are surprisingly easy to do.

[@danmcclaren5436]

Beautiful video. Concise, clear, visual, and straight to the point. I also liked the the physics with free body diagrams. Great video!

[@CasualNavigation]

Thanks Dan. Glad you liked it.

[@jefftube58]

Thanks for such a concise and simple explanation !

[@CasualNavigation]

Thanks jefftube58

[@billhrsn]

Very helpful in understanding how a flat bottom ship or boat stays upright. We follow a narrow boat cruiser on the British canal system, and people would always ask about our sailboat and if it would tip over. No one is concerned about a bass boat, power boat, or cruise ship tipping over.

[@acrobaticcripple8176]

So simply explained. Thank you.

[@CasualNavigation]

Thanks Acrobatic Cripple

[@ranchlife4792]

I’ll never look at any boat the same again, esp those huge mega cruise ships which seem to get taller and taller. Great job ✨

[@cerebralm]

So it's the square bottom that makes it work? does this mean there are other hull shapes that are less stable?

[@stevecurtis1088]

Yes if the bottom was more like a semi circle (much like a yacht) then it would have zero self righting.

[@aceroadholder2185]

@@stevecurtis1088 Well it would be stable if the center of buoyancy was above the center of gravity. The weighted keel of a sailing vessel insures that is the case. As I understand it, there is a "sweet spot" in a normal hull of how much difference there should be between the CB and CG (the meta-center height) so that the vessel will have a stable oscillation or roll when in normal sea conditions and have good roll recovery in heavy seas and wind. If the meta-center is too great it becomes too much of a good thing. Instead of rolling the ship would tend to be pushed over pivoting more about the keel than the center of gravity into the lee side water making recovery sluggish. Cruise ships seem a lot like a barge in having a negative meta-center height thus depending on wide beam and shallow draft to provide stability.

[@stevecurtis1088]

@@aceroadholder2185 That makes sense. Yes I suppose it's like any sort of oscillating/damping challenge where you can optimise for stability against a given level of agitation. Ie you can make a boat more stable/smooth in calm conditions but it will be unstable in rough conditions. Or you can make a boat more stable in rough conditions but it'll give a harsh ride in more gentle conditions.

[@John_Snowbird]

Very nicely explained. The best explanation of center of buoyancy that I've heard is that it's the center of gravity of the hole that the ship makes in the water.

[@carultch]

More like the centroid, than the center of gravity. Centroid is a geometrical term that doesn't care about kilograms or gravity, rather than a physical term that does. It is the center of gravity of the region, if it were filled with a uniform density material.

[@KeithGadget]

So, towards the end of the cruise where lots of weight of stores and fuel has been expended, the ship will be more at risk of capsize?

[@CasualNavigation]

Theoretically yes. But in reality the weight of stores and fuel is replaced with ballast water so the ship remains stable.

[@daveroberts6884]

In warships they can consume their stores and fuel and replace the lost mass with water ballast. Failure to do this has lead to ships being lost when they encounter storm conditions in a light ship condition.

[@mandiola2010]

-I am a former skipper who worked on side and stern trawlers here in Chile. Hope we had this kind of videos time ago. -Good job.

[@MagnarNordal]

I have learned something new. Thanks!

[@HughPryor]

"Because of their shape" is the reason I thought boats floated. Now I have an understanding of it in terms of centre of gravity and centre of buoyancy being in balance.

[@observersnt]

excellent communication skills. maximum information conveyed with irreducible minimum of words and simple illustrations that explain complex issues. Wish all would be you tube experts were as good as this. Thank you so much

[@CasualNavigation]

Thanks for the kind remarks Andy!

[@shatter382]

i feel like this does a good job of explaining what it explains.the thing is this is just the explanation of why ships stay up in general. most people clicking on this would be looking at cruise ships in particular, and an answer that would address the fact forces applied higher up on the ships would have a greater impact on pushing the ship over, than those near the waterline. also the higher. also the higher the center of the mass the less of a tilt is required to push the ship past the point of no return.

[@CasualNavigation]

Thanks for the comment Dan. As you say, I have kept this video generic, only explaining the broad details. I may expand on it in the future, though the topic is so large it would take a very long video to cover it all.

[@RonakDhakan]

What would happen if the center of gravity was below the center of buoyancy? Would it make the ship more stable?

[@longbeachboy57]

Yes. That is how many sailboats are designed. Most of the weight is in the keel, and if the boat capsizes the COG will be above the COB and the boat will right itself again...

[@brandonmtb3767]

Subbed! First video from you that I have seen. KZbins algorithms found me another channel. Great explanation. I feel smarter

[@CasualNavigation]

Thanks Pinhead Larry. Glad you enjoyed the content

[@SuccessforLifester]

Buoyancy is not in the syllabus for secondary school students. It is quite an abstract idea

[@jamesmccann5644]

It was in my syllabus for GCSE science. GCSE's are taken in secondary school in the UK.

[@SuccessforLifester]

@@jamesmccann5644 Was it in the old syllabus?

[@BooBaddyBig]

AFAIK buoyancy usually is (Archimedes principle), but stability isn't.

[@jamesmccann5644]

@@SuccessforLifester yeah, did it about 5 years ago now.

[@jamesmccann5644]

@@BooBaddyBig not directly, but the different forces causing buoyancy, and moments are. So all the components are. There was just no section saying that moments happen with buoyancy as well.

[@ship_facts]

Awesome Video! Well done

[@VinayKumar-db4qz]

I worked on Royal Caribbean for eight years.

[@williamokeefe918]

Great video, but I noticed one thing; the image shown from 10 to 20 secs one isn’t a cruise ship. It’s the RMS Queen Mary 2, a transatlantic ocean liner run by Cunard. Still, it was very interesting!

[@camdentrain]

This was and incredibly interesting topic, thank you for creating such a lovely video about it!

[@CasualNavigation]

Thanks camdentrain. Glad you enjoyed it!

[@LeeEngle]

Thank you, I've often wondered why aircraft carriers with the massive island off to one side stayed upright, and I believe that this theory applies there as well.

[@HANKSANDY69420]

Yep

[@Black_Jesus3005]

Always wondered this. Thank you

[@CasualNavigation]

Glad I could help!

[@richardtheeighth4431]

I know the title of your video, along with the visual effect is intended to capture interest. It's doing the job brilliantly. In addition to the wonderful content and comments, i'll add my piece, because nobody has bothered to in the past year, hopefully it might generate more interest for you. It's my understanding fall means to lose one's balance and collapse to the ground. Falling/tip/tipping from an upright position. To fall over oneself or an object. The glass of liquid tipped over. Capsize is defined as a boat rolling over onto its side or completely over. I guess that's defined as flooding, as long as the ship maintains some boyancy. If a ship was unfortunate to end up on the bottom of the ocean, because it capsiized, then it didn't fall there, because it sank, after it capsiized.⛴⚓️🛳

[@alxjetson8157]

If a giant wave hits the side, then what?

[@CasualNavigation]

If it hits the side with enough force/energy to overcome the ship's righting force/energy, then yes, the ship will capsize. It is more likely is that a wave that size would break the superstructure and flood the vessel before capsizing it though.

[@plasmastar2374]

Poseidon (2006)

[@CasualNavigation]

Thanks Plasmastar 23. Poseidon is only fiction though

[@fhuber7507]

There was a cruise liner that did get hit by a wave and rolled to the point of inability to self-right. It laid over on its side for a long time before going keel-up.

[@daveroberts6884]

The point of no return. There are charts of this for every ship for each condition, heavy, regular, light and drydock loads. Not sure of the terminology but if a heel of x degrees is exceeded on any vessel it will stay over or capsize.

[@swisswildpicsswp3095]

Why am I addicted to boats and ships videos? I don't even live near the sea and fear open waters

[@ScepticPJ]

Excellent video. Educational, clear, understandable and without dreadful musack. If only more videos were like this! I have for years wondered why these top-heavy giants don't just tip over , sorry, capsize. Thank you.

[@CasualNavigation]

Thank you for the comments Peter! Glad it answered your questions.

[@prashantmahesvara3564]

Informative! Thanks for making this video explaining how it works.

[@marksadventures3889]

Errr They do! Recent history gives us quite a few I think you'll find.

[@Li.Siyuan]

Interesting. Obvious when you think about it, but not so obvious until it's been explained. Nice one and thank you.

[@SnarkierThan-U-R]

LOL, Initially I not see the Over word and thought that by "Tip"it was going to be about not leaving a gratuity for staff.

[@jacksoltren9247]

Casual navigator, I was a Quartermaster on board a US Navy ship. I understood the fundamentals of buoyancy and CG. However, that was many years ago and, the way you explained was an awesome job. It puts many things in perspective. Thanks fellow Navigator. Very good job. By the way, I subbed.

[@CasualNavigation]

Thanks Jack. I am pleased you liked the delivery. There are so many technical sources, I wanted to communicate the fundamentals in a way everyone can understand.

[@jahroos7469]

Keep up the great 👍 work ✌🏿🇯🇲

[@CasualNavigation]

Thanks Jah Roos!

[@valblome4913]

Coming from a pilot perspective, I'm making comparisons to weight and balance computations for airplanes. (Center of gravity and center of lift in that example.) I'm enough of a nerd that I want to see what weight and balance calculations for ships look like. I'm curious how similar or unique those processes are.

[@lizlovsdagmara5525]

I was thinking the same.

[@rosskesava]

I found that interesting and informative and described in simple terms.

[@CasualNavigation]

Thanks for the comments Ross!

[@rosskesava]

I rarely comment on youtube videos but was glad to do in this instance. Thank you for the thanks.

[@zniloserkrf5790]

Thank you, I've read at least one explanation of CC versus CB. This video makes the matter so much more clear.

[@OneKindWord]

It still doesn't reassure me; if anything, it makes my stomach tighten more. I'm staying on land. But I'll wave bon voyage to you from the dock.

[@CasualNavigation]

The sea isn't for everyone OneKindWord.

[@1oldmariner]

Lucid and simple. Everyone can understand this!

[@CasualNavigation]

Thanks 1oldmariner. That was the aim, so I am glad it came across that way

[@_dank_memesvines_2576]

On all modern ships today,if winds/rough seas occur,stabilizers will come out of the hull of the ship and help balance so that the ship does not capsize.great vid though...keep up the good work😃

[@CasualNavigation]

hyper X, thanks for the comments. Stabilizers are fitted to most passenger ships, but all they do is dampen the roll to make it more comfortable. They aren't actually needed to prevent a capsize.

[@al35mm]

Yes, stabilizers do not change the CofG or buoyancy, they work hydrodynamically to counter roll for the purposes of making the motion more comfortable for passengers.

[@mrreymundo5383]

I recently took a cruise and was disappointed by how effective the stabilizers were. I was hoping to feel the roll of the ocean more. It was more like being in a tall building in a breeze, unfortunately.

[@liveluke777]

hyper X i agree and i have seen 3 cruise ships go over and stay on their side. I've seen far to many people die from Cpts trusting exactly what you mentioned just to have them fail. It's super rare of course. Yet, it does happen and typically from MASSIVE waves. Especially, rougue waves! Some of these Captains believe they are so unsinkable they will tell you a hurricane is just really ruff water. Storms can create waves way ovet 100' w/ a much larger trough. In huge storms these can easily knock over these ships as the equipment to warn of a rogue, etc... Can appear to quickly or be camouflaged by breaking waves and rain/hail keeping crew blind at the worst moments. Worst for me was hearing a specific one go under before we could get close. None of us thought we were coming back yet we made our peace and tried till we realized what was happening from what lil we could make out till radio silence. Later it was stated how the Capt knew his ship did not have the proper integrity for that level of Hurricane. He got blamed for all of it. Yet when we checked charts, timing , etc..: he actually took best course available. Screw those thinking they r unsinkable in this way. It just takes mother nature to decide y'all r not needed to her. I really hate people thinking humans have mastered mother nature. She will forever win.

[@daveroberts6884]

Nor are they used to prevent capsize. Only correct stability can prevent that. Horizontal rudders only counter roll.

[@primeverdeen45]

The first photo is qm2 i think. she’s a ocean liner (Not being rude or correcting sarcasticly)

[@huypham2911]

10kg??? I’m more concerned about chubby people jumping 🤣🤣

[@neelroy2918]

This is kind of explanation that results in existential questions "but why o why buoyancy and gravity *have to* balance each other?" and you end up depending on anthropic principle "because if they dont ships cant exist."

[@TheCalgarycanuck]

Ships don't tip over, they capsize.

[@CasualNavigation]

Thanks for the comment. You are right. The correct term is "capsize". In my more recent videos, there is a lot more terminology. This video is very much only a basic introduction to some concepts.

[@Keestral]

Well in this case you are talking about listing. Capsizing is the end result of too much listing.

[@jamesjacocks6221]

Harvey Millar. You are correct, ships capsize, but boats, crewed by lubbers, tip over all the time. Pretty good explanation of center of buoyancy?

[@TheCalgarycanuck]

Really, most reports of ships capsizing say it capsized or over turned , not tip over

[@tjhaze204]

Jesus people get over yourselves. No one cares how much you know about ship terminology

[@keithmorrison5463]

As always your tutorials are great! Be good to see more videos on stability! Thanks

[@CasualNavigation]

Thanks Keith

[@idlewild1964]

Thats all good until you breach the hull! Remember the costa concordia? Take on enough water and that top heavy bastard is gonna roll! Good luck launching life boats on the high side!

[@CasualNavigation]

You are 100% correct. This does all only apply if the hull is intact. As soon as there is a breach, the stability situation changes completely.

[@idlewild1964]

The Casual Navigator i think when engineers design a ship they should go back in time and study how so many passenger liners have sank in the past! Too many liners have been lost! The ocean floor is littered with them!

[@TheCalgarycanuck]

Not all sinkings caused design but many by human error.

[@TheCalgarycanuck]

Oops 'by design'

[@idlewild1964]

Harvey Millar human error usually initiates the sinking process without a doubt but the physical process of the ship sinking often exposes design flaws or shortcommings! Imagine if the titanic was a double hulled ship with true water tight compartments!

[@joehillary6981]

2:35 error... Wind is not an external force that causes a cruise ship to roll. It is wave action that does this (i.e. when waves strike the side of the ship hull).

[@nickparkin8527]

"Slap bang in the middle"

[@Tina06019]

Thank you, this is the best explanation I’ve heard. I have always disliked the ‘look’ of modern cruise ships b/c they don’t look like ships. “What’s that skyscraper doing out on the water?”

[@CasualNavigation]

Thanks Tina. They do look like a skyscraper at sea. Especially the modern ones!

[@sirankleknocker3122]

Is queen Mary 2 a part of your comment?

[@FlyViews737]

Short answer *There to god dang heavy*

[@kuthegorix]

they're*

[@FlyViews737]

Alex Moss lol

[@jasexavier]

You corrected "There" to "They're", but not "to" to "too"? I'm shocked.

[@kuthegorix]

you can't hand everything to others on a silver platter.

[@FlyViews737]

jasexavier to dose not matter to me

[@vaclav_fejt]

And this is why you don't see tumblehome hulls around much.

[@amen6755]

What happened to costa Concordia then?

[@richardlamb71]

it hit rock bottom, literally, all the physics in the video, mean nothing of you have holes below the water line

[@seanpresley6725]

It hit a rock and water entered the ship from the bottom, adding more weight to the ship, causing a capsize.

[@aadonisk]

Water came flowing in, changing the wight of the ship.

[@jamesjacocks6221]

Live On. It almost tipped over. Had it been captained by a salt it never would have come to grief. It was captained by a boy clown so it tipped a bit.

[@fhuber7507]

Concordia ripped a hole IN ONE SIDE and flooded compartments on that side. It drastically moved the CG to that side AND removed buoyancy from that side moving the CB (Center of Buoyancy) to the other side. Slide the Green dot a LOT left and the blue dot a LOT to the right and as the ship rolls it just makes it want to roll more, rather than self-correct. The gyro stabilizers can deal with this on a relatively small scale (similar to all the passengers going to the left side of the ship at the same time to watch whales), but they don't work when you put water in their compartment shorting them out and adding the water friction acting on the gyro discs. They stop pretty fast when that happens. Before the water could move to the undamaged side of the ship through open hatches, the ship had rolled beyond its maximum list for self righting even with the gyros working and it flopped on over until the superstructure (everything permanently bolted to the ship above the hull) hit the dirt rocks and coral. Just not enough positive stability built in to deal with a hole that the ship could have survived if it didn't roll and not enough pumping capability to force water into "trim tanks" fast enough to counter the roll. And the ship "turned turtle" (the part of a capsized hull sticking up out of the water, of a 1800's sailing ship, resembles a turtle shell) ******************* USS Enterprise hit an underwater mountain and DAMN NEAR capsized. They expected it to go down due to the ship exceeding max unladen list angle by several degrees. Fuel, weapons storage and supplies being stored low + high capacity trim pumps + using fire hoses to purposefully flood compartments kept it upright (and a lot lower in the water moving CB up)

[@lewis7315]

I should mention that when the ship is moving, it has small underwater moveable wings "trim rudders" you could call them at the bottom of the sides of the ship that helps to keep the ship upright,,, as well as "bilge keels" that help keep the ship from rolling...

[@theklb1]

QM2 is not a cruise ship, she's a liner.

[@CasualNavigation]

QM2 was built as a liner, but is used as a cruise ship. She does still serve as a liner for a bit each summer, but she is mainly used as a cruise ship nowadays.

[@THypher1]

She is a dual purpose Ocean Liner/Cruise Ship as was QE2. She is doing more Transatlantic crossings than ever these days (into November for example).

[@eduardovalino7054]

ships are ships having all principle of keeping them upright

[@alanhilder1883]

liners go into the bin don't they?

[@Anvilshock]

They're all big honkin' floaty tubs to me.

[@vigeee]

You need more than the center of the waterplane area at 1:58 to determine the centre of buoyancy. The centre of buoyancy is basically the centre of gravity of the displaced volume so you need to know the complete form of the displaced volume to be able to obtain the coordinates for the center of buoyancy.

[@CasualNavigation]

Thanks Vigee. I did mean the centre of the underwater volume at that part. The diagram is correct for volume, I just said waterplane area.

[@vigeee]

Otherwise this explains the fundamental theory of ship stability very well

[@drak3385]

just make videos like these 2 mins max and youll get alot more views

[@CasualNavigation]

Thanks for the tip Mr Documentary. I was considering a run of shorter videos to gauge interest, but I will still also continue the longer ones as those are the ones I enjoy making.

[@drak3385]

i mean you can make longer videos, its not that, its just this particular subject is not going to keep someone watching 5 mins

[@drak3385]

something seems off with the audio recording also, not sure if getting a better mic would fix it. The audio just doesnt seem polished I guess is the best way to explain it.

[@drak3385]

Also, put a little more time into the graphics. It will help add retention and subscribers by giving it all a more polished look.

[@CasualNavigation]

Cheers. I only started making videos in December, and this was one of the early ones. Very much learning as I go. I only used kit that I already had as well, so the mic was just from my ps4 headset. I have replaced that now, so hopefully there will be improvements on newer videos. As for graphics, I only use open source (free) applications, and am learning those as I go too. Again, hopefully there will be improvements in time, just through practise and any investment as I can afford it. Thanks for the tips though!

[@markrobbins9552]

Wow this is a fantastic video. At first I thought all you have to say is because it's heavier on the bottom. Aware of the effects of shifting weight around but understanding the mechanics of it is going to help. Thanks.

[@stuartlee6622]

The Queen Mary 2 is NOT a cruise ship!!!!!!

[@ThornyA_D39]

Stuart Lee the fuck is it then

[@AntPDC]

@@ThornyA_D39 An ocean liner.

[@The_Deztro]

There is no reason I should be addicted to your vidios and yet hear I am

[@the_rover1]

simples. it's due to a flat earth's surface. that's why a cruise vessel that big doesn't roll over. kappa :D

[@jillcherry-bukowiec231]

Loving the fact that it said cruise ships but the thumbnail shows an ocean liner LOL

[@junkim1884]

Thanks for sharing this simple infos. And i think, aside from sort of liquids and heavy machines underneath as with pulling gravity and its proper arragements of cargoes, etc, aside from bouyancy above... they could control it thru a certain built-in gadget at the Captain's deck area to check the ship's balance situation in 24/7 monitoring.

[@dougsturgess2651]

Glad I found this site. Answers a lot of questions my curious mind has. Thank you.

[@RickyJr46]

The best explanations are often the simplest ones- very well done!

[@KBYTE]

This video is actually a great help because i want to be a sea fairer when i'm older, as of now i'm still 16 years old and enrolling of a maritime university. My course yet is going to be a señor high shool student.

[@CasualNavigation]

Thanks k-byte. Glad the content is helping you. Good luck with your chosen career.

[@KBYTE]

The Casual Navigator thanks!😂

[@jonnynik7626]

No idea why this popped into my recommended videos, but somehow I'm happy it did.

[@CasualNavigation]

Glad you liked it Jonny!

[@widget3672]

Brilliant explanation, thank you for the time you took to make this!

[@CasualNavigation]

Thanks for the comment Widget

[@grosbeakmc]

You point is concise, well explained and nicely illustrated. Thanks for sharing!

[@Sunflower_Man]

My guy forgot about: Costa Concordia, Diamond Sea, e.t.c.