The SAA X-mark Protractor is used to measure an azimuth offset angle between a known direction and the physical X-Mark on a ShapeArray (SAA). Applying this measured offset angle to the data through Measurand's software will allow the axes in the ShapeArray data to be oriented to real world directions.
NOTE - For ShapeArrays with one or more magnetometers (optionally available in SAAF or SAAV only), it is typically not necessary to use the SAA X-mark Protractor. The readings from a ShapeArray with magnetometers are automatically adjusted to correspond to +X = magnetic North. For ShapeArrays with one or more magnetometers, the protractor would only be required if some direction reference (other than magnetic North) were desired.
Step 1 - Place the Square Protractor
Place the square white protractor with the arrows around the extension tube at the top of the ShapeArray. SAAV's installed in larger diameter casings will have square fibreglass extension tubes (shown on the left of figure below ). SAAVs and SAAFs installed in 27 mm ID conduit will have round PEX extension tubes (shown on the right of the figure below). Rotate the square protractor until the arrows are pointed to one of the following:
- The expected direction of movement (e.g. downhill)
- Other job site datum (e.g. survey marker or North)
Figure 1: The square protractor placed around the extension tube at the top of the ShapeArray and oriented to the desired direction - (left) fibreglass, extension, (right) PEX extension
Step 2 - Place and Align the Clear Disk
Place the clear disk with the X-Line around the extension tube on top of the square protractor so that the X-Line is aligned with X-Mark on the extension tube. The X-line on the clear disk, the X-Mark on ShapeArray, and the X-mark on the Extension Tube should now all be aligned.
Figure 2: The clear disk aligned with the X-Mark on the extension tubes and the square protractor - (left) fibreglass extension, (right) PEX extension
Step 3 - Read the Angle
Make note of the azimuth offset angle at the X-Line. This will be directly used in the software to rotate the X-mark axis of the ShapeArray towards a known direction. For more information, you can refer to the following documentation:
- SAARecorder manual, section SAA Setup | Site Properties
- SAAView manual, section Azi and Aza
- SAACR_raw2data manual, section Configure Conversion Settings
NOTE: Attached to this article are printable versions of the X-Mark Protractor dial and wheel. The wheel portion of the protractor is designed to be printed on clear, transparent plastic.