Originally Posted by PCP
Just have a look at two boats, with similar types of hulls, about the same size, one with 4.5T and a substantial part of its weight down on a bulb at the end of a 3m draft, the other one with 9T with much more proportion of weight in its hull and 1.55m of draft. Both are well designed boats thetotal RM would not be very different (due to the much bigger mass of the heavier boat) and the lighter boat will be massively stiffer.
We are talking here about a 40 class racer and about an Oceanis 41.
Just for kicks, I decided to check your original premise. Contrary to what you say, these boats have radically different hulls. Not sure why you even posted this.
And contrary to what you say, they have radically different RM diagrams. The racers RM would be considerably higher by a wide margin. Not sure why you posted this.
Is the Racer 40 stiffer. Probably, but then again nothing you said originally was true.
The racer has 50% more hull moment only due to its increased width. I would have to look closer at the mass moment. This boat has an RM quite higher than the Oceanis. Again.. where did you come up with the idea these boats had similar RMs?