Ships on the sea don't have brakes like cars, so how does a fast-moving ship slow down and stop?
In general, there are four braking methods for ships, the first is the more familiar thrust reverser device, which is the propeller reversal, which changes the direction of the water flow by 180 degrees, cancels the forward kinetic energy, and achieves the purpose of stopping the ship. The ship relies on the engine to drive the propeller, and the speed of the propeller determines its travel speed. When a moving ship is about to stop, slow down and drive against the current for a while. This is because after the engine stops running, the ship will move forward a while under the action of inertia, so it needs to use the reverse current to help the hull "brake" faster.
This method is only suitable for all-electric propulsion ships, most ships are now all-electric propulsion, at this time there will be a motor on the spindle, control it to reverse, the motor reversal is much faster than the steam engine reversal!
The second is the attenuation of kinetic energy or the use of the convection direction of the ship and the water to achieve the stop of the ship. Left full rudder, right full rudder, left full rudder and right full rudder, using the angle of the ship's rudder to slow down, this mode can also play a partial deceleration role.
The third is a steering device on a warship or a 10,000-ton giant ship, which can also be called auxiliary braking, which is similar to a propeller steering mechanism (stabilizer fin) of a ship under water in the bow, and when the ship is docked, it is used with the rudder to achieve lateral propulsion to achieve deceleration. (The stabilizer fin is a bit like the fin of a fish, the function is to reduce the rocking of the ship, but it can be adjusted in angle, just like the flaps of an airplane, the full lift is also the largest, and of course the drag is also the largest)
A ship with a stabilizer fin sticking out
The fourth is to break down, and I personally feel that this should also be regarded as an auxiliary brake, just like parking and pulling the handbrake, which will only be used in an emergency. The anchor of a large ship can exceed 100 tons, but it is ineffective to anchor if the water depth is too deep, after all, the anchor chain length is limited, even if the anchor chain of the Nimitz aircraft carrier is only about 1500 meters, and the average water depth in the Pacific Ocean is 4000 meters, so it is useless to anchor in many positions!
However, the ship is still effective in shallow water, and the anchor will be dragged after sinking to the bottom of the sea, which will play a great role in slowing down the ship, but if it is suddenly stuck, it is estimated that even the entire windlass can be pulled out of the ship!
If you take the ship many times, you will find an interesting phenomenon: whenever the ship is about to dock, it always tries to put the bow of the ship against the flowing water, and uses the deceleration effect of the reverse current to slowly slope towards the pier, and then smoothly land.
This is because when approaching downstream downstream, the speed of the ship on the opposite shore is equal to the speed of the ship plus the speed of the water; When approaching against the current, the speed of the ship on the opposite shore is equal to the speed of the ship and the speed of the water is reduced. Obviously, the former is much larger than the latter, and the countercurrent docking speed is smaller, making it easier to dock.