Thanks to the square cube law, you can't linearly extrapolate the displacement from a 150m ship to a 54m one. Looking at some random ships in roughly that size

Thanks to the square cube law, you can't linearly extrapolate the displacement from a 150m ship to a 54m one. Looking at some random ships in roughly that size one can see e.g. - https://en.wikipedia.org/wiki/Stavros_S_Niarchos https://en.wikipedia.org/wiki/Stavros_S_Niarchos sailing ship of 59m, 635 tons - https://en.wikipedia.org/wiki/Gepard-class_fast_attack_craft https://en.wikipedia.org/wiki/Gepard-class_fast_attack_craft German naval ship, 58m, 390 tons. Considering it was a yacht with relatively fine lines, even taking into account the ballast, 540 tons seems about ok.