# Hydrostatics - Which point has higher pressure?

1. Jan 16, 2010

### IBY

Just a little question. Say a boat is floating on water. Imagine now two points in the shallow, flat sea floor. One is below the ship and the other is just water all the way up. Which point has higher pressure?

I am imagining that both points have the same pressure due to the concept of hydrostatic pressure:
$$\rho g h$$
But still, I have a little doubt. Wouldn't the boat add a little more pressure along with the atmospheric one?

2. Jan 16, 2010

### PhanthomJay

Re: Hydrostatic

you are correct
Unlike solids or soils, water is almost incompressible, so for all intent and pupose, it would not add pressure
the pressure at the given point in the water is the sum of the atmospheric pressure plus the water 'gauge' pressure you noted in your equation.

3. Jan 16, 2010

### Phrak

Re: Hydrostatic

The pressures are equal. The boat acts as though it is the volume of water it displaces.

4. Jan 16, 2010

### IBY

Re: Hydrostatic

Thanks!

5. Jan 16, 2010

### ehild

Re: Hydrostatic

Think: part of the boat is under water, so the height of the water column beneath it is less than h.

ehild