pvb
Well-known member
Having read through the thread, there seems to be a theme here I noticed on an earlier thread, namely people conflating 'Displacement' and 'weight'. From my rudimentary knowledge of Naval Architecture, Displacement is an indication of volume, rather than an indication of the weight of an object (and pertinently to this thread the weight of worked materials used in the construction of said object).
This is particularly noticeable on larger yachts where clever trickery in relation to Hullforms is used to bring the displacement down so they do not have to conform to a higher standard of regulation, but the actual weight of the vessel is significantly above this.
My point being that I'm not sure all those people who are quoting 'Displacement - Ballast = Construction weight' aren't barking up the wrong tree.
I'm afraid you may be confusing "tonnage" with "displacement". Tonnage is indeed related to volume. Displacement is very definitely related to weight.