We have seen it in Hollywood plenty, in Netflix series, and even in commercials; cars being thrown off cliffs and ending up sinking in a lake or large body of water.
There are many discrepancies between how long you see the car above the surface of the water before it vanishes completely.
- In some movies the car vanishes which a minute flat.
- In others, it takes a whole 5 minutes before the car completely sinks into the depths.
So how fast does it take for a car to sink in water?
The speed at which a car sink depends on the distance of the fall, speed, and angle of entry, and the physical characteristics of the vehicle and generally float between 30 and 120 seconds before sinking.
Common sense will tell you that a heavier car will sink faster than a lighter car.
- Cars usually sink at an angle, with the weight of the engine pulling the car down be it the front or the back.
- The greater the distance of the fall the faster the car sinks as the impact from the entry of the vehicle into the water will cause the car to be damaged resulting in holes and gaps for the water to enter.
- Likewise, the faster the car is traveling before impact, the greater the damage done to the vehicle and again the faster the car falls to the depths due to the condition of the vehicle.
A field test was done near Winnipeg, Canada where prototype systems were installed on two used cars at a gravel pit lake. All fluids were drained from the vehicles and a crane was used to place the vehicles in the lake either by lowering them straight down into the water or by swinging the vehicle into the water.
For upright immersions:
- In both static and dynamic tests, the windows opened immediately and effectively when the vehicles landed upright in the water.
- In each case, the windows were open before the water rose to the level of the windows letting the car sink slower into the lake.
- Inverted immersions: Once vehicles are lowered into the water in an inverted position regardless of the static or dynamic position of the vehicle, the windows opened quickly, and the vehicle sank quickly while remaining in the inverted position due to the entrance of water through the windows.
- Cars and pickup trucks are inherently stable in the upright position because of the mass and low position, of the motor.
- Therefore, if passenger vehicles land in the water upside down, and the windows are closed and remain intact, the vehicles will eventually right themselves by rolling on the x-axis.
Likewise, vehicles landing in the water at a steep angle will also eventually settle in the upright position. Even at a steep angle of up to 60° or more, a vehicle will penetrate the water and then bob back up in the upright position making it more likely for a vehicle to sink slower if the windows are closed and are intact.
Most importantly, the windows of the car as well as the door play a crucial role in the speed of submersion.
- Once the window is open or the door the water will rush into the car at a faster rate resulting in the car sinking faster than before.
- The door opening increases the rate for the car to sink more than the window obviously due to its larger gap. The faster the water enters the vehicle's interior, the faster it loses its buoyancy and the quicker it descends.
- If both windows and doors are closed however the car will be able to float longer before sinking due to the air bubble within the car keeping the car buoyant for longer.
Vehicles that are better at isolating sound will also be better at keeping water out due to their water tightness and thus lack of gaps in the body of the car.
These are factors that affect the speed of a car sinking into a water body. Hopefully, you never need to utilize these points. However, remembering these points may be the difference between life and death if you ever find yourself in such a situation.