Amidships

Amidships denotes the midlength of the ship, the point halfway between the forward and after perpendiculars, marked by the circled-cross symbol on the lines plan and drawings. It is the reference station for the midship section, where beam and depth are usually maximum and the midship section coefficient Cm is defined. Note the distinction from the geometric center of the waterline or LCB: amidships is fixed at 0.5 LBP, whereas LCB and LCF generally sit forward or aft of it depending on hull form. Hydrostatic tables, the offsets table, and the curve of areas all index station numbers about amidships, conventionally station 10 of 20 or station 5 of 10.