Dave, My earlier note of caution was prompted by the thought that the gross tonnage of a merchant vessel is not necessarily a reliable method for comparing ships of broadly similar size - especially those built at different times. I assume that, in the case of the ‘Olympic’ class, a large proportion of the hull space would have been filled with boilers, coal bunkers etc, whereas the machinery spaces on the Canberra would have been much smaller. Would this not have had an impact of their relative GTs? However, if the Canberra had a smaller displacement, this (coupled with her slightly shorter overall length) would imply that she was indeed a good deal smaller than the Titanic.