John
having experienced a lot of this practice myself, I take and agree your points-- but not necessarily the reference to just ore loading. I think it is being overlooked that it was common practice in larger bulk carriers when in lightship passage to fully ballast just ONE hold, something in the order of 20+k tonnes water ballast-- if my memory serves me well, generally No6, ie around mid-point of the ship's length-- with the facility to also ballast 2,4,8 in some ships in which I sailed, though not necessarily to hatch coaming depth-- thus, similar shearing forces at the frames between holds as in, for example loading, 1,3,5,7,9, with 2,4,6,8 empty, would, on the ballast passage, be also applied, but only in ONE section of the hull structure rather than five.