The larger boat should displace more water
, all else being equal. However, there are a lot of things that are not equal between the two examples.
In this case, you can step aboard both and see why the Catalac
displaces more water.
In general, if you have an oak cube, 1cuft in volume floating next to a balsa
cube of the same volume, which one displaces more?
The answer to that question is the same as the example between the Catalac and Gemini
. One is made out of heavier stuff and one is made out of lighter stuff.