Will there be any change in water level/height of floating part of the boat if stones are dropped into the pond from a floating boat?
The weight of the water displaced by the hull of a floating boat equals the total weight of the boat and its contents. This is called "Archimedes Principle", and is true of any object floating in any fluid.
If stones are removed from the boat, it becomes lighter and displaces less water. That
means it rises up so that less of its volume is below the surface. The change in the submerged volume of the boat equals the volume of water weighing the same as the stones removed.
If, for example, 2.2 pounds (about 1 kg) of stones are removed, that is the weight of about one liter of water. The boat would rise until 1 liter, or 1000 cubic centimeters, less of its hull's volume remained below the water line.
Paul Walorski, B.A., Part-time Physics/Astronomy Instructor
If something is submerged in water, it will displace an amount of water equal to its volume. If something is floating in water, it will displace an amount of water equal to its weight. Therefore, if you have anything more dense than water (stones) floating in a boat and you throw it into the water, the water level will go down because the object displaces less water when submerged.
Eric Newman, B.S.
'One thing I have learned in a long life: that all our science, measured against reality, is primitive and childlike - and yet it is the most precious thing we have.'