Choose Open Marker Data from the File menu. Select the file titled ‘Yacht Offsets’ and open it. This file contains a table of markers for a simple yacht hull form. When it is read in, it will fill the Markers window with marker data, and the markers will be displayed in the Plan, Profile, Body Plan and Perspective views. Each marker point is displayed as a cross in the view windows.

To edit the markers, bring the Markers/Offsets table to the front by choosing Markers from the Window menu. The markers are displayed in a table and you can scroll through the data to examine the markers at any station.

The Markers window is similar to the Markers window in Maxsurf. The column headings are: Position (longitudinal position); Offset (transverse position) and Height (vertical position). The markers are grouped in stations. The first and last groups, or fields, are labelled Bow and Stern in the Station column.

These two groups allow the specification of the bow and stern shape that do not necessarily lie on an individual, planar station, as is the case with the other station fields.

The bow and stern definitions are important as they describe the fore and aft edges of the surface that you will create using Prefit. Note that the longitudinal position of each bow and stern marker may be changed, allowing either to be raked; in general all other sections are vertical (i.e. specified with a constant station position). Markers for each station should be entered in order starting at the centreline and moving out towards the sheerline. Similarly, markers for the bow and stern should start at the keel and move towards the sheerline.