How come geese and over water birds doesn't sink? They are quite heavy and probably don't possess lesser density than water
they stay afloat thanks to the Archimedean force of pushing out of the water, due to the presence of grease on the feathers, as well as a large number of air cavities between the feathers
@argentum So you think density of the bird plays the leading role?
@chaoticgood it's not about density, but about its volume and the material that is on its surface. If we take the same ships, neither of them have such airy materials as birds have, however, due to the shape, the Archimedean force plays a decisive role
For ships, several factors are involved in the process of providing buoyancy, including the shape of the ship, its strength, and the means provided to resist waves. In general, a ship will float if the volume of water it displaces weighs more than the ship itself. In such a ship, the upward force of water pressure on the hull will overcome the downward force of gravity, which can be considered applied at one point, called the center of gravity. Ships are said to remain stable (in the language of specialists, stability) if, after heeling forces from factors such as waves or wind, they can return to an even keel. If the ship is not properly designed or loaded, such external influences can lead to loss of stability and the ship may sink.
As far as I know shape of feavers plays important role too. Increase of surface Area of hydrophobic materials leads to increase in hydrophobicity all together