Swings

What is a swing?

A swing is an angular offset stored in the drawing that R3Survey applies to every bearing you type in R3TRAV. It lets you enter bearings from your field notes or plan directly, without manually converting them to match the drawing's coordinate system.

Why do you need a swing?

Survey drawings often have a rotation between:

• the plan/field bearing system (the bearings on your DP or survey notes), and
• the drawing coordinate system (the grid or arbitrary north used in the CAD file)

Without a swing, you would need to mentally add or subtract the rotation difference to every bearing before typing it. With a swing set correctly, you just type the bearing from your notes and R3Survey handles the conversion.

A practical example

Suppose your survey notes record a boundary as bearing 45° 30' 20", but the drawing's coordinate system is rotated 5° 00' 00" counterclockwise relative to grid north. If you type 45.3020, R3Survey draws the line at 40° 30' 20" to account for the rotation.

The swing value in this case would be 5° 00' 00" and is subtracted from each entered bearing.

Setting a swing

Use R3SWING to open the swing form. You can:

• Type a value — enter the swing angle directly in DMS format
• Pick a line — select a line or polyline segment in the drawing; you then specify what bearing that line should represent; the swing is calculated as the difference

Swing persistence

Swings are stored in the drawing file using extended data (XData). Each drawing has its own swing. When you switch drawings, the swing for the active drawing is loaded.

Traversing with a swing active

When R3TRAV starts and a swing is active, a warning is shown in the command line. This is a reminder — not an error. If you did not intend to have a swing active, use R3SWING to clear it before entering the traverse.

Disabling swings temporarily

In the swing form, you can disable swings without clearing the stored value. This suspends the adjustment while keeping the angle saved, so you can re-enable it later.