4 ms·
When water gets squeezed between a ship’s hull and a sand floor, it speeds up. As water flow speeds up, its pressure drops, pulling the hull down to fill the va
by ummonk 6y ago
When water gets squeezed between a ship’s hull and a sand floor, it speeds up. As water flow speeds up, its pressure drops, pulling the hull down to fill the vacuum. The effect is more pronounced at the stern, and so the ship settles into a squat: bow up, stern down.
Yet another article that needlessly complicated things by invoking the Bernoulli principle. It’s a lot simpler to explain: the space behind the stern needs to suck water into it so the stern area is at lower pressure, while the space around the bow needs to push water out of the way so it’s at higher pressure. The closer you are to the sea floor or bank, the bigger the effect since there isn’t much space to push water away and pull water from.
- JxLS-cpgbe0 6y agoYour explanation is longer and harder to understand. (How do you "invoke" Bernoulli's principle?)
- deleted 6y ago[deleted]
- simonh 6y agoWhy do they need to be at higher or lower pressure? That doesn't explain anything.
- bopbeepboop 6y agoThe ship is moving. The bow moves water out of the way when it moves forward and the stern vacates space which the water fills. So water is going away from the bow (positive pressure) but towards the stern (negative pressure). When a ship travels, water moves from the front to the back — and this shifting the water creates pressure as the water moves (which is also where drag comes from). If the water only has a narrow space to move, it has to move faster through that area, so the pressure is higher/lower. (Higher before where it bunches up on the bow, lower after where it rushes to fill behind the stern.) If one side has more space than the other (eg, left has less space) the the water goes faster on that side and so the pressures on that side are more extreme (eg, pushing the left bow rightward and sucking the left stern leftward — turning the ship right). That is, the normal front-to-back pressure can cause a twisting force if the flow isn’t balanced left-to-right. Because the side with less flow ends up with water bunching up at the front and not enough in the back.
- fian 6y agohttps://en.wikipedia.org/wiki/Squat_effect https://en.wikipedia.org/wiki/Squat_effect
- cryptonector 6y agoPressure in fluids is a funny thing. Put your thumb at the open end of a hose with water flowing through it: you'll feel high pressure. But along the sides of the hose the pressure from the flowing water will be a lot lower, and if you poke a hole into the side while leaving the open end open, then you might even observe that hole sucking air in!
- cbkeller 6y agoThanks, this actually explains the "turning" component of the bank effect much more intuitively (to me anyways).
- neolog 6y agoI understand yours but not the quoted one. Thanks.