A yacht drops its anchor overboard. What happens to the water
We are going to use the Archimedes principle of buoyancy.
Let’s say that the mass of the yacht is M and the mass of the anchor is m. The density of water is ρw and the density of the anchor is ρa. When the anchor is in the yacht, the volume of water displaced is
V1 = (M + m) / ρw = M / ρw + m / ρw
and when the anchor is in the water, the volume of water displaced is
V2 = M / ρw + m / ρa
It’s obviously that
ρa > ρw
V1 > V2
Thereby, the water level falls when the yacht drops anchor overboard.