Lightship Definition

In any particular design, only a single lightship definition can exist at any given time.

In order to edit and subsequently update the lightship definition, you can select the Ship Data - Lightweight icon, and then the Edit command. The lightship particulars can be entered as a single item or as a more detailed and itemised weight breakdown and distribution. As well as specifying the weight and centre of gravity of each item, you are able to include a free surface moment if desired and appropriate to liquid contents. Also, where accurate longitudinal strength calculations are to be performed, each item should be described by giving its fore and aft extents in order to enable the corresponding weight distribution to be determined. A ramp weight distribution, of typical quadrilateral form between aft and fore extents, is assumed for each item.

A running summary of the current total lightship weight, the position of the overall centre of gravity (LCG, TCG and VCG), and the total FSM, is displayed at the bottom of the input dialog. This provides a simple but useful check function following the progressive entry of individual data items.