Markers are reference marks displayed on the screen. They may be offset data that has originated from an existing hull or simply limiting dimensions that need to be visible while developing a design.

Markers are purely graphical and have no effect on the calculation of surfaces. The maximum number of markers you may use is 30000. In practice you will usually use many fewer than this.

Markers may either be read in with a design from Prefit, read directly from a text file or by Importing DXF Markers. Markers can also be entered manually using the Add Marker function in the Edit menu or copied and pasted into the markers table from another application such as a spreadsheet. They are stored as three-dimensional points in space and may be added, moved or deleted. All marker positions are stored in the design file whenever you save a design.

Each marker can be associated with a station in your design. Usually if you are importing markers that form the offsets of an existing design, you will set up the grid in Maxsurf to match the station spacing of the original design, and then set the station number of each marker to match its station in the offsets table. See Generating a Grid from Markers on page 138 for more information on automatically generating a grid from a set of markers.

Markers may also be associated or linked to a specific surface and location in that surface. Once linked to a surface, the marker takes on the colour of that surface. This function may be controlled with "Use Surface Colour for Drawing Parametrics" control in the View | Preferences dialog. If this control is turned off, markers that have been linked to a surface will be displayed in the same colour as the surface parametrics. This is not only useful for display purposes but can also be used to Measure Surface Errors and utilise the Fit Surface to Markers Command that is available when you Activate/Deactivate Prefit.

To turn all markers on or off

·   Select the Markers function from the Display menu.

You can choose to display all markers or no markers, or you may choose to only show those markers whose station number is the same as the current station.

In the design views, markers may be selected in a similar manner to the control points: by simply clicking on them with the left mouse button or by dragging a box around them. Holding down the Shift or Control key while making the selection allows you to add more markers to the current selection or remove previously selected markers from the selection.

Selected markers are highlighted in the highlighting colour.

In the Markers table, you may only make a continuous selection. However, data may be sorted by right clicking in the column header and choosing from the pop-up menu to sort ascending or descending based on the contents of that column. The markers may be unsorted by right clicking in any of the column headers and selecting Unsort Rows from the pop-up menu:

To add a marker to a drawing window

·   Select Add Marker from the Marker menu or use the Ctrl+M shortcut key.

A pencil cursor will be displayed.

·   Click the mouse at the position of the new marker.

Use the position indicators to place the marker at the required position. The added marker will be associated with the current station as displayed in the control box.

Markers may also be placed graphically in the Plan or Profile views. For these 2D views, the third dimension takes the value of the last entered marker. For example, if you wanted to enter makers on the 2m waterline, first switch to the Plan view. Add a marker in the Plan view; double click the marker so that you can specify its height as 2m, then any subsequently added markers (in the Plan view) will have their height at 2m. Markers on Buttock lines may be entered in a similar fashion in the Profile view.

Alternatively, a marker can be added directly into the Markers window. To do this

·   Select the Markers window.

·   Highlight a row by clicking in the far left hand column.

·   Select Add Marker from the Edit menu.

·   Enter the number of markers you wish to add and hit Return.

Rows will be added after the row selected, with cells initialised to zero.

To delete a marker from a drawing window

·   Select the marker(s) to be deleted

·   Select Delete Marker from the Marker menu or use the Delete key on your keyboard

·   Click yes to confirm you want to delete the selected markers.

The marker will be deleted.

To delete a marker from the Markers window

·   Select the Markers window

·   Select the row(s) of the marker(s) that you wish to delete

·   Select Delete Marker from the Marker Menu or use the Delete key on your keyboard

·   Click yes to confirm you want to delete the selected markers.

Rows will be deleted from the Markers window.

The co-ordinates in the Markers window may be edited to move a marker in space. To edit a marker

·   Click on a cell in the Markers window.

·   Enter the changed Station Number, Longitudinal Position, Offset, or Height.

Alternatively, to edit a marker directly

·   Double click on a marker in one of the drawing windows.

A small dialog box will appear containing data about the marker. You may select and edit any of the marker's co-ordinates. When you click OK the marker will be updated to the new position.

You may also set the data for a number of markers together:

·   Select the markers in one of the drawing windows.

·   Select Properties from the Markers menu.

If you have selected several markers, those fields that contain exactly the same data for all the selected markers will be displayed with the common data. If the data differs, the field will be left blank. Editing the data in any field will update all the selected markers. This can be useful for making sure that all the markers on one station have identical longitudinal positions, or for specifying which section they should be linked to.

It is possible to read a text file of markers into Maxsurf. This text file may be created from the Save Markers or Save Offsets commands in Maxsurf or created in a spreadsheet, word processor or other application.

The format for the Markers file is tab delimited text. Each coordinate is separated by a Tab character, and each line ends with a Carriage Return character. An example would be:

Column 1 is the station number with which the marker is associated. This controls when the marker is displayed and when it is hidden when the Show Markers for Current Station command is active. Column 2 is the longitudinal position from the zero point, Column 3 the offset from the centreline and column 4 the height above the zero point.

Alternatively you may create markers by Importing DXF Markers. The DXF file is imported by choosing File | Import | DXF markers.

The order in which markers are sorted along a section line can be important when the marker data is used in Prefit to automatically generate a surface, or when you want to use the marker-connection-lines as a reference during manual surface fitting tasks.

Markers that have been assigned to the same Station Index can be sorted for each station using the Sort Marker Stations command from the Markers menu. This sorting uses a nearest neighbour sort, which works in most instances, but can be confounded if the section shape is complex and/or the spacing between markers varies significantly. To view the connectivity (and ordering) of the markers turn on the Display | Connect Marker Stations option: Ctrl+J, . This is best done in the Body Plan view, with the Display | Show Markers for Current Station option selected ().

A single marker can be moved along the ordering by using Ctrl+Cursor keys; left and down keys move the point one positions towards the start of the ordering whilst up and right keys move the point one position towards the end of the ordering; the Home key makes it the first point and the End key makes the it the last point:

Before and after: Moving the selected point one position towards the start of the curve corrects the marker ordering

To re-order a range of markers, select them in the new desired order (from the keel outwards towards the deck edge (or deck centre line) and select Markers | Re-order Selected Markers (Ctrl+Shift+R). If the new order is the reverse of what is required, simply repeat the command without changing the selection, and the order will be reversed.

Points are now ordered in the selection order, if this is the inverse of what is required, simply repeat the Use Re-Order Selected Markers command without changing the selection.

When a marker is added, it will be inserted to so as to minimise the increase in section length. This normally ensures that it is inserted in the correct location.

To generate markers that describe the shape of the developable surface you have to first set the surface type to Developable. This will create ruling lines from the surface edges from which the markers can be generated using the Markers | Generate Markers for Developable Surfaces command. This command is only available if there is at least one surface in the design with the surface type set to developable surface.

See Surface Types on page 90 for more information

Markers are calculated for the surfaces selected in the list on the left of the dialog (only developable surfaces are listed). Markers can be generated where the ruling lines intersect stations previously defined in the Grid Spacing dialog, or at equal intervals along the ruling lines. The number of ruling lines calculated depends on the current surface precision setting, but during the generate markers command the precision is increased temporarily to highest.

Markers generated at equal intervals along the ruling lines – this is useful for the automated surface fitting (Markers | Fit surface to Markers) as it ensures that markers are generated even when the rulings are vertical and do not interest stations.

Markers generated where they intersect the sections. This is useful when manually fitting the surface to the markers in the body plan view.