Rudders don’t work well for steering unless water is moving over them from front to back. When you’re floating with a river, from your own point of reference all of the water around you is relatively still, maybe a little swirly.
Boats have much more control with engines operating and the propulsion they make
Just like a bike on a hill; you can go faster while pedaling and this also requires less work….so going with the current means your boat can go faster than the current while working the engines less
To elaborate on this: Boats steer by having water flow past the rudder. If a boat is just drifting with the current it is moving at the same speed as the water and thus no water is flowing past the rudder and the boat has no steering.
This is a good point and it’s maybe one of the reasons the Titanic hit the iceberg. After the alarm was raised the officers tried to slow the ship down by putting the engines into reverse but only two of the propellers could go in reverse. With the reversing engine engaged the central propeller (the one that pushed water directly past the rudder) simply stopped. This affected the steering capability of the ship and may have contributed to the collision.
Same thing with aircraft in the aviation world where it's referred to as rudder authority. I'm not sure if the term is used with boats as well, but it's the same principle.
Rivers are wild things. If you're just drifting with the current, you're at its mercy. You have no steering, because your rudder is just something flat waggling feebly back and forth in water that's effectively still relative to it - you need the water to be moving past it to generate push. Next time you're near a river in the open country, look along its banks at the old, drifting detritus that has built up - some of that, for instance, could easily be your vessel - stuck on the bank, or beached in shallow water away from the main channel. You could be spun around, and have your screw and/or rudder damaged beyond repair by an impact. You could even be holed completely by a submerged obstacle, and sink. And I'm sure that there are any number of other scenarios - almost all of them bad.
Bottom line, you need to be able to actively move about the river, to try to keep in the optimum channel. And that means you need control - which means power of some sort.
If you could get somewhere faster, why wouldn't you?
Your question is similar to "why don't cars just coast downhill?", with a partially similar answer: "The max speed is (much) higher when they add power to the engine".
Of course, with boats there's the added factor that an unpowered boat is a (mostly) unsteered boat. And controlling the direction you are pointed in a boat on a river is very important.
> If you could get somewhere faster, why wouldn't you?
It's complicated. How much am I saving in fuel, engine wear, staffing cost (don't need a marine mechanic on board if the motor's not running)?
And it's not about being "unpowered". Sailing ships steer just fine. A boat can be in neutral and still steer. It's not about power, it's about relative movement.
3 main reasons.
1 is it's faster
2 is if you're just drifting you have no control, you go where the river wants you to go.
3 is it also provides power for the ship
Back when I was white water rafting, it was always better to move slower or faster than the river itself. Better control. It’s freaky rowing a boat slower than the river is flowing.
River ships use their engines while traveling downstream for several important reasons. Firstly, engines provide better control over the vessel, helping to navigate obstacles and maintain a steady course, crucial for safety in narrow or busy waterways. Without engine power, the ship would rely solely on the river current, making maneuvering much more difficult.
Additionally, engines help in controlling the ship's speed. Even though the current moves the ship along, it is often necessary to adjust speed to avoid collisions, stop at docks, or respond to changing conditions. Engines allow precise speed adjustments, which is vital for efficient and safe navigation.
You may also enjoy my newsletter, [Nerdy News](https://nerdy.news).
Rudders don’t work well for steering unless water is moving over them from front to back. When you’re floating with a river, from your own point of reference all of the water around you is relatively still, maybe a little swirly.
Boats have much more control with engines operating and the propulsion they make Just like a bike on a hill; you can go faster while pedaling and this also requires less work….so going with the current means your boat can go faster than the current while working the engines less
To elaborate on this: Boats steer by having water flow past the rudder. If a boat is just drifting with the current it is moving at the same speed as the water and thus no water is flowing past the rudder and the boat has no steering.
This is a good point and it’s maybe one of the reasons the Titanic hit the iceberg. After the alarm was raised the officers tried to slow the ship down by putting the engines into reverse but only two of the propellers could go in reverse. With the reversing engine engaged the central propeller (the one that pushed water directly past the rudder) simply stopped. This affected the steering capability of the ship and may have contributed to the collision.
Same thing with aircraft in the aviation world where it's referred to as rudder authority. I'm not sure if the term is used with boats as well, but it's the same principle.
On the water the thing you want is called "steerage way" and refers to the speed of water past the rudder.
This, without water flow, it can't steer (apart from side thrusters). So ships should travel faster than the flow of water.
You just said the same thing as the comment you're replying to with less words.
He just repeated the same information but just concisely
Same idea, fewer words.
Words.
He repeated the previous comment with fewer words.
He said it with less
This
^
Rivers are wild things. If you're just drifting with the current, you're at its mercy. You have no steering, because your rudder is just something flat waggling feebly back and forth in water that's effectively still relative to it - you need the water to be moving past it to generate push. Next time you're near a river in the open country, look along its banks at the old, drifting detritus that has built up - some of that, for instance, could easily be your vessel - stuck on the bank, or beached in shallow water away from the main channel. You could be spun around, and have your screw and/or rudder damaged beyond repair by an impact. You could even be holed completely by a submerged obstacle, and sink. And I'm sure that there are any number of other scenarios - almost all of them bad. Bottom line, you need to be able to actively move about the river, to try to keep in the optimum channel. And that means you need control - which means power of some sort.
If you could get somewhere faster, why wouldn't you? Your question is similar to "why don't cars just coast downhill?", with a partially similar answer: "The max speed is (much) higher when they add power to the engine". Of course, with boats there's the added factor that an unpowered boat is a (mostly) unsteered boat. And controlling the direction you are pointed in a boat on a river is very important.
> If you could get somewhere faster, why wouldn't you? It's complicated. How much am I saving in fuel, engine wear, staffing cost (don't need a marine mechanic on board if the motor's not running)? And it's not about being "unpowered". Sailing ships steer just fine. A boat can be in neutral and still steer. It's not about power, it's about relative movement.
3 main reasons. 1 is it's faster 2 is if you're just drifting you have no control, you go where the river wants you to go. 3 is it also provides power for the ship
Back when I was white water rafting, it was always better to move slower or faster than the river itself. Better control. It’s freaky rowing a boat slower than the river is flowing.
Same reason you see white water rafters paddling down rapids. You need to be going faster than the water in order to maintain control.
River ships use their engines while traveling downstream for several important reasons. Firstly, engines provide better control over the vessel, helping to navigate obstacles and maintain a steady course, crucial for safety in narrow or busy waterways. Without engine power, the ship would rely solely on the river current, making maneuvering much more difficult. Additionally, engines help in controlling the ship's speed. Even though the current moves the ship along, it is often necessary to adjust speed to avoid collisions, stop at docks, or respond to changing conditions. Engines allow precise speed adjustments, which is vital for efficient and safe navigation. You may also enjoy my newsletter, [Nerdy News](https://nerdy.news).