The comparison between Calypso and the Comus class pauses over what a listed ship length actually measures. Length between perpendiculars runs from the center of the rudder head aft to the bow's intersection with the loaded waterline. That working waterline is distinguished from the Plimsoll line, and a lower loading line can preserve a safety margin before the ship reaches its limit. The boundary between underwater and topside paint can also offer a rough visual warning that a merchant vessel is sitting too deep. The perpendicular measurement also feeds into turning-circle calculations. Ship dimensions are conventions tied to safe loading and maneuvering rather than simple end-to-end measurements.
Notable Point · 17:12-19:10
Length between perpendiculars and safe load lines
Calypso's dimensions prompt an explanation of length between perpendiculars, loaded waterlines, Plimsoll lines, and why naval measurements matter operationally.