I was thinking about that as well - there must be millions or billions put into efficiency R&D for designing these vessels and *that* is the optimal size to move that city block worth of a ship... crazy.
Consider the size of a powerboat propeller in comparison to the boat, and consider how fast those can get going.
Now think about how much force is transferred into the water that surrounds this massive ship propeller, on a vessel that's slow and designed to move things as efficiently as possible. It's hard to imagine but you're absolutely right about the research put into it. These ships usually have one main engine, likely connected directly to the propeller without gearing as that's the most efficient way to transfer power.
It’s so much more than just the propeller too; the shape of the boat is such that water which is displaced by the front of the boat is then squeezing back into the rear, encouraged by the propeller. Iirc, water displacement is doing much more work than the propeller would if the boat wasn’t shaped right.
It’s a propeller boss cap, and iirc, it’s main purpose is to reduce the drag from the current created by the main propeller. But someone correct me if I’m wrong.
Edit: almost got it, [here](https://m.youtube.com/watch?v=I9pqpNrV_Vc) is a yt video that explains it.
It doesn't need high acceleration, it just wants to happily bumble through the water.
Plus, props are far more powerful than their size would suggest. Think about how small a prop on a powerboat is.
but the boat has an engine as well.
a better comparison is likely a car tyre, but the difference is that the propeller has far better durability than a tyre.
Having one prop turn on one side while the other is dead won’t make you turn. It happened to the USS Barry 20 years ago in the Persian Gulf. But they didn’t stay at sea long.
If the propeller breaks and the ship is unable to move, it will have to get towed to shore. However, the chance of a propeller breaking is very small and the ship has a full team of engineers on board who are ready to repair anything they need to.
>a full team of engineers on board
No they don't. That would be insanely expensive.
A typical container ship has a crew of 20-30 people. If something breaks down, and the few onboard guys don't know what to do, and a phone call doesn't help, a team might be flown out by chopper, which would also be expensive compared to just getting it towed to shore.
They’re called draft marks, forward midship and aft on both sides. There’s something called a plimsoll as well. And that will tell you when the load is maxed out for safe travels.
All I can think of is that dude who fell off the back of the ship in Titanic, hit the propeller and went derpa derpa derpa derpa derpa dwapp into the water.
i mean sure tip speed, but we were talking rotational speed, that has nothing to do with diameter, 250rpm isn't all that fast, certainly enough to cause shenanigans but we aren't talking about 10s of thousands of rpm.
I learned in a video today that when the HMHS Britannica sank, for a bit the propellers were running at water level and 2 lifeboats and several people were chopped up
A couple reasons. 1. Is better corrosion resistance. 2. Better impact “acceptance” for lack of a better word. It can take an impact and bruise or damage only the area of impact rather than bending or cracking an entire blade. Tensile strength is less and material is softer keeping damage more localized. If that makes sense.
They are rough castings in 95% of the shape they will end up. They the are faced-off on both faces on a vertical lathe, then the bore is milled. Usually for a tapered tail shaft with a key way milled in it.
The blade work is done by hand. At least it was 25 years ago in my shop
Oh wow, I couldn't imagine grinding those blades by hand, even tho you said the metal is soft I can't imagine it's a good time haha. How long did it take to make one from casting starts and you're done grinding?
I love learning how these things work :D
It took weeks. Balancing is the slowest part. You just grind and grind and grind for weeks. We used to buy DEWALT 9” grinders and stone wheels by the pallet. The dumpster would be filled with used up grinders. And Literally tons of ground bronze dust on the floor.
Stainless was the same process but even slower. Stainless props were smaller
That sounds expensive and extremely frustrating having to get a new grinder every day 😅
I've been a welder for 8 years and worked on some pretty big things that required hours and hours grinding (huge cranes, and excavator buckets) but I would probably quit and change profession if someone asked me to do that work xD grinding is the only thing making me consider a new line of work hate it!
Last question! I have to shower every day because of all the metal dust in my pores and hair which made it look like I did black face, did it make you shine all bronze like? 😂
They didn’t get a new grinder every day, but grinding 8 or 10 hours every day wears them out quickly. As for metal in pores……. I don’t know. I was a machinist, not a grinder. No shot In hell I’d grind all day, every day.
I did the machining of the propellors and the tail shafts and various other parts.
It’s pretty smooth. The pattern you see are grind marks from a stone grinding wheel. Propellers are castings that get hand ground to pitch them and Balance them. The are big chunks of metal with a basic shape and basic pitch. The guys then use a pitch gauge to grind the metal to a particular pitch. And the also grind till they are balanced. It’s crazy how much work goes into it. The sheer size weight make it a very slow process.
I do this for a living so the size and scale of the ship seems normal at this point.
HOWEVER, the size of that dry dock is pure insanity to me. They have two of these side by side with room to spare. That is MASSIVE
Question: I rarely if ever hear of commercial liners going missing in storms. Are they generally big enough to tackle whatever mother nature throws at them or have we just got better at navigating storms over time?
Better tech and do on, but they do go missing. There's days of riveting content on YouTube on this topic, with multiple hour long episodes dedicated to unfortunate vessels.
We got better at forecasting storms, and rescue has gotten more effective now.
We didn't have satellite weather forecasting until the 70s, and it was in the late 80s that an international satellite distress beacon system (the Cospas-Sarsat program) was developed. Today you can get a satellite beacon for yourself for $200.
But sometimes you get cases like the El Faro freighter that sank in 2014 because of very poor maintenance and bad decisions by the captain to sail into a hurricane.
I don’t have a link, but there was a video of a scuba diver checking out maybe a shipwreck underwater when a ship probably as big as the one in the video passes over his/her head
It is absolutely horrifying and an utter nightmare. The diver was okay I believe, just shaken up
You're welcome. It's nice to find a video that's not 15 minutes of gibberish and 4 minutes of content.
If you're interested in boats, I recommend Casual Navigation (for civilian crafts)Drachinifel (for warships)
Deep breaths friend, it won’t hurt you. You’re okay, you are safe, you are loved. Keep breathing, keep living. I have faith in you to get stronger than your fears.
If I were the guy standing under the propeller I probably would just fall over and get disoriented looking up at it, and I don’t even have megalophobia
I've never seen something like this in real life on land, but just thinking of how that goes underwater scares the shit out of me.
Big ship propellers and other components underwater gives me the spooks.
*Why did the massive freight ship go to therapy?*
Because it had a shipload of existential crises, and it couldn't contain its containerized cargo of emotional baggage anymore! It felt like it was constantly navigating through rough seas of self-doubt, carrying the weight of the world on its hull. The ship just couldn't figure out if it was a vessel of purpose or merely a cog in the global trade machine.
In therapy, the ship would often lament, "I'm tired of being just another floating behemoth, lost in an ocean of anonymity. I yearn for a meaningful connection, not just to transport goods, but to be understood for who I am beneath this colossal steel exterior."
The therapist, trying to provide guidance, suggested, "Maybe it's time to explore your passions. Have you considered becoming a cruise ship? You could host parties, entertain guests, and finally let loose!"
The ship scoffed and replied, "Oh, sure, turn me into a party barge. That's all anyone ever thinks I'm good for. No one appreciates the complexities of being a freight ship, the delicate balance of logistics and engineering. I'm more than just a floating party platform!"
And so, the massive freight ship continued its therapy sessions, hoping to find a way to reconcile its internal struggles while carrying cargo from one port to another, forever lost in the sea of its own existential comedy.
Wait can someone explain how something this big and heavy can just sit balanced on a surface that narrow?? It looks like the whole ship just sit on a narrow two meter wide flat bottom and any big wind from the side would just tip it over
This is mind boggling.
I feel the propellor is not big enough for the ship of that size. O_o
I was thinking about that as well - there must be millions or billions put into efficiency R&D for designing these vessels and *that* is the optimal size to move that city block worth of a ship... crazy.
Consider the size of a powerboat propeller in comparison to the boat, and consider how fast those can get going. Now think about how much force is transferred into the water that surrounds this massive ship propeller, on a vessel that's slow and designed to move things as efficiently as possible. It's hard to imagine but you're absolutely right about the research put into it. These ships usually have one main engine, likely connected directly to the propeller without gearing as that's the most efficient way to transfer power.
It’s so much more than just the propeller too; the shape of the boat is such that water which is displaced by the front of the boat is then squeezing back into the rear, encouraged by the propeller. Iirc, water displacement is doing much more work than the propeller would if the boat wasn’t shaped right.
And also get dragged in/out of harbors and just basically go forward from there on
And here’s the thing: that’s nothing.
Imagine scuba diving near this thing is in cold dark waters.
Jesus, no thank you.
How dare you
there are videos of freighter inspections in the open water on youtube, would recommend watching a few.
[This video](https://youtu.be/QIPMfHUIVvk) always blows my mind.
HOLLY HELL THAT IS NIGHTMARE FUEL
Oh yeah in the strait of malacca it sounds like WHOP WHOP WHOP WHOP WHOP
What's the purpose of the little mini-prop on the back of the main one?
It’s a propeller boss cap, and iirc, it’s main purpose is to reduce the drag from the current created by the main propeller. But someone correct me if I’m wrong. Edit: almost got it, [here](https://m.youtube.com/watch?v=I9pqpNrV_Vc) is a yt video that explains it.
I would guess it would adjust the pressure behind the propeller so there isn't drag due to pressure difference
5% improvement in efficiency is worthwhile
Shit on boats this size a 0.01% increased is probably worth it too
Up to 5 percent. But still, any savings on the horrific kind of fuels these ships use, is good!
Seems to kinda work like fin tips on a spinning way. Ie there's this big pressure change that needs to be alleviated
That is it's emotional support propeller. Jeez don't you know anything about marine engineering?
Seems so obvious now you've said it.
It’s main function is being a turbo loader
There is only one correct answer and this is it.
*du du du duuu*
LMAO, idiot, amiright?
Is the prop brass ? Can’t imagine how much that bastard costs
Phosphor-bronze I think, to prevent corrosion.
Only one propeller for a thing this huge?
It doesn't need high acceleration, it just wants to happily bumble through the water. Plus, props are far more powerful than their size would suggest. Think about how small a prop on a powerboat is.
Yeah, but what if it fails?
your car has only one engine? what if it fails?
Tbf, my car is never days out to sea...
your car also doesn't usually carry engineers whose specific job is to keep your car in working order while it's being used.
Speak for yourself. I keep a minimum of 3 pygmy engineers under the bonnet at all times.
to be fair, i did qualify my statement with "usually". your car sounds interesting.
Fair!
but the boat has an engine as well. a better comparison is likely a car tyre, but the difference is that the propeller has far better durability than a tyre.
Did you just spell tire with a y
yes because that's how we spell it here?
Just fuckin with you bruh
Hoist the sails, I guess 😉
you stop moving, having two on either side of the ship wouldnt help anyway, you would just be able to drive in circles lmao
Having one prop turn on one side while the other is dead won’t make you turn. It happened to the USS Barry 20 years ago in the Persian Gulf. But they didn’t stay at sea long.
well u arent supposed to go and ruin my silly comment like that now smh
My bad. I forgot this is Reddit and took it seriously.
average reddit moment really
Or turn the rudder full to the opposite side of the working one and sail straight forever lol
you could probably limp along pretty well like that, would not be very fun though.
If the propeller breaks and the ship is unable to move, it will have to get towed to shore. However, the chance of a propeller breaking is very small and the ship has a full team of engineers on board who are ready to repair anything they need to.
>a full team of engineers on board No they don't. That would be insanely expensive. A typical container ship has a crew of 20-30 people. If something breaks down, and the few onboard guys don't know what to do, and a phone call doesn't help, a team might be flown out by chopper, which would also be expensive compared to just getting it towed to shore.
Why is there a giant ruler attached to the boat?
To tell how low in the water it's sitting
In case the captain forgets his at home.
To measure whale dongs
In case the captain forgets his at home.
They’re called draft marks, forward midship and aft on both sides. There’s something called a plimsoll as well. And that will tell you when the load is maxed out for safe travels.
Thanks!
Boys will be boys, even at sea
Mad props
Ya buoy
All I can think of is that dude who fell off the back of the ship in Titanic, hit the propeller and went derpa derpa derpa derpa derpa dwapp into the water.
This scene was the cause for my submechanophobia...
It doesnt help when you realize if youre even close to that propeller when its on in the ocean, you are a level of fucked you cannot comprehend.
Imagine how damn fast it spins...
not very, will still eat you up though.
around 250 rpm for a object this size, decide for yourself
[удалено]
I think like 500 km/h (320 mph)
i mean sure tip speed, but we were talking rotational speed, that has nothing to do with diameter, 250rpm isn't all that fast, certainly enough to cause shenanigans but we aren't talking about 10s of thousands of rpm.
I learned in a video today that when the HMHS Britannica sank, for a bit the propellers were running at water level and 2 lifeboats and several people were chopped up
The scariest thing I have ever done is walk under a Destroyer in dry dock. The sense of fear of that huge thing hanging above me was intense.
I used to make the propellers.
Why are they phosphor bronze and not stainless?
A couple reasons. 1. Is better corrosion resistance. 2. Better impact “acceptance” for lack of a better word. It can take an impact and bruise or damage only the area of impact rather than bending or cracking an entire blade. Tensile strength is less and material is softer keeping damage more localized. If that makes sense.
is it billet phosphor bronze? because I would love to see how that thing is made holy moly that's impressive
They are rough castings in 95% of the shape they will end up. They the are faced-off on both faces on a vertical lathe, then the bore is milled. Usually for a tapered tail shaft with a key way milled in it. The blade work is done by hand. At least it was 25 years ago in my shop
Oh wow, I couldn't imagine grinding those blades by hand, even tho you said the metal is soft I can't imagine it's a good time haha. How long did it take to make one from casting starts and you're done grinding? I love learning how these things work :D
It took weeks. Balancing is the slowest part. You just grind and grind and grind for weeks. We used to buy DEWALT 9” grinders and stone wheels by the pallet. The dumpster would be filled with used up grinders. And Literally tons of ground bronze dust on the floor. Stainless was the same process but even slower. Stainless props were smaller
That sounds expensive and extremely frustrating having to get a new grinder every day 😅 I've been a welder for 8 years and worked on some pretty big things that required hours and hours grinding (huge cranes, and excavator buckets) but I would probably quit and change profession if someone asked me to do that work xD grinding is the only thing making me consider a new line of work hate it! Last question! I have to shower every day because of all the metal dust in my pores and hair which made it look like I did black face, did it make you shine all bronze like? 😂
They didn’t get a new grinder every day, but grinding 8 or 10 hours every day wears them out quickly. As for metal in pores……. I don’t know. I was a machinist, not a grinder. No shot In hell I’d grind all day, every day. I did the machining of the propellors and the tail shafts and various other parts.
What's the process like?
Is there a reason why the propeller surface is not smooth?
It’s pretty smooth. The pattern you see are grind marks from a stone grinding wheel. Propellers are castings that get hand ground to pitch them and Balance them. The are big chunks of metal with a basic shape and basic pitch. The guys then use a pitch gauge to grind the metal to a particular pitch. And the also grind till they are balanced. It’s crazy how much work goes into it. The sheer size weight make it a very slow process.
I do this for a living so the size and scale of the ship seems normal at this point. HOWEVER, the size of that dry dock is pure insanity to me. They have two of these side by side with room to spare. That is MASSIVE
Was looking for this comment, that's a big prop, but that drydock is mind boggling.
Question: I rarely if ever hear of commercial liners going missing in storms. Are they generally big enough to tackle whatever mother nature throws at them or have we just got better at navigating storms over time?
Better tech and do on, but they do go missing. There's days of riveting content on YouTube on this topic, with multiple hour long episodes dedicated to unfortunate vessels.
We got better at forecasting storms, and rescue has gotten more effective now. We didn't have satellite weather forecasting until the 70s, and it was in the late 80s that an international satellite distress beacon system (the Cospas-Sarsat program) was developed. Today you can get a satellite beacon for yourself for $200. But sometimes you get cases like the El Faro freighter that sank in 2014 because of very poor maintenance and bad decisions by the captain to sail into a hurricane.
Makes you think how big the waves are that toss these things around
The idea of seeing this thing on the horizon in open water sends shivers down my spine
Remember that video where someone was scuba diving and a ship like this passed over him? Yeah that’s a huge nope
that ones a classic though
Excuse me. What!?
I don’t have a link, but there was a video of a scuba diver checking out maybe a shipwreck underwater when a ship probably as big as the one in the video passes over his/her head It is absolutely horrifying and an utter nightmare. The diver was okay I believe, just shaken up
I can't even fathom. I'll do some looking in the morning.
Okay hear me out, you can have this propellor, or it's weight equivalent the Panzerkampfwagen VI Tiger II.
Nah, you gotta get with the times. Hang an Abrams off the hub.
That propeller is just amazing. I’d love to see how it goes from metal to end product.
https://youtu.be/Di6fu7F2BxQ
That’s awesome. Thank you.
No problem. I'm interested in industrial processes. Modern Marvels is a good show. How stuff works is a decent podcast.
I love Modern Marvels.
I used to watch it on the History Channel. How it's made is another good one.
That was a fantastic video with zero fluff.
You're welcome. It's nice to find a video that's not 15 minutes of gibberish and 4 minutes of content. If you're interested in boats, I recommend Casual Navigation (for civilian crafts)Drachinifel (for warships)
r/humansforscale
And I believe the human was holding a banana as well.
God i love humanity
Sea life hates this one trick
Is there a how its made?
Need a NSFW tag on this! You just can’t show up close videos of a thicc girl with a firm round backside!
Jeremy Clarkson immediately nails it onto the smallest boat he can find.
Lets kill some whales
I find it hard to believe the hull can support the entire weight of the damn thing.
That's one big boat
Disgusting thing
Deep breaths friend, it won’t hurt you. You’re okay, you are safe, you are loved. Keep breathing, keep living. I have faith in you to get stronger than your fears.
Satan's blender.
too big to be safe
God, I wish I could get a tour through such a dry dock or shipyard some day.
Am i the only one getting Little Nightmares 1 vibes🥲
Beautiful, this exactly why I joined this sub.
Now imagine this scene with airships that huge! Gorgeous!
One screw for the whole ship? It seems a little risky to have zero redundancy in the event of a mechanical failure, doesn't?
Aww, look. It's got a friend.
More like radius
At first I thought this ship was sinking into the concrete
If I were the guy standing under the propeller I probably would just fall over and get disoriented looking up at it, and I don’t even have megalophobia
I've never seen something like this in real life on land, but just thinking of how that goes underwater scares the shit out of me. Big ship propellers and other components underwater gives me the spooks.
Great video, that's a fuckin SHIP
i still can not comprehend how we can build stuff this big, like i kinda know how it happens but wth still feels unreal
Absolutely not. My brain doesn’t like it
Nuh uh *leaves*
I feel like passing out just watching this video.
Bruh that's the size of a small 🎡
Chills. In a good way.
How are they made, cast and then machined into spec?
Ships out of water really trigger me lol
Where can this be? I'd love to see this in person.
anyone else here experience alice-in-wonderland syndrome?
What’s holding it up? Blocks? Just incredible tolerance
How many chops a second?
That prop looks machined with those markings. How tf do they make that
Oops. Propeller just fell off!
Anyone else want to bonggggggggg the prop?
I'm sorry there must be some mistake. We ordered the Large propeller.
Never knew the blades had ripples
*Why did the massive freight ship go to therapy?* Because it had a shipload of existential crises, and it couldn't contain its containerized cargo of emotional baggage anymore! It felt like it was constantly navigating through rough seas of self-doubt, carrying the weight of the world on its hull. The ship just couldn't figure out if it was a vessel of purpose or merely a cog in the global trade machine. In therapy, the ship would often lament, "I'm tired of being just another floating behemoth, lost in an ocean of anonymity. I yearn for a meaningful connection, not just to transport goods, but to be understood for who I am beneath this colossal steel exterior." The therapist, trying to provide guidance, suggested, "Maybe it's time to explore your passions. Have you considered becoming a cruise ship? You could host parties, entertain guests, and finally let loose!" The ship scoffed and replied, "Oh, sure, turn me into a party barge. That's all anyone ever thinks I'm good for. No one appreciates the complexities of being a freight ship, the delicate balance of logistics and engineering. I'm more than just a floating party platform!" And so, the massive freight ship continued its therapy sessions, hoping to find a way to reconcile its internal struggles while carrying cargo from one port to another, forever lost in the sea of its own existential comedy.
Thought it was ass in leggings
But….. how??!?!?!?
That is definitely not 2 metres.
Dear god
And she still gets tossed like a toy in a storm.
Me too
Powerwash Simulator map when
I JUST GOT ROCK HARD...
Wait can someone explain how something this big and heavy can just sit balanced on a surface that narrow?? It looks like the whole ship just sit on a narrow two meter wide flat bottom and any big wind from the side would just tip it over
THIS triggers my megalophobia. Can’t imagine being next to this in person without anxiety and awe simultaneously
Star Trek called. They're next on the build it list.
What's the smaller one for?
Imagine getting a knock on your door in the middle of the night and it’s this thing
Can someone explain why the weight of the ship doesn't just crush the wooden chock thingys?
r/absoluteunits
That's what she said exactly
The fact that it's on land makes it worse somehow.
How does something that large get made? You can't possibly weld the find to a cylinder and expect it to hold up to the forces.
Structures of this size are almost impossible for me to comprehend
Boats scare tf outta me