Preliminary Instructions for Survey of the Compass Rose

CNATRAINST 11130.1D

16 June 1999

PRELIMINARY INSTRUCTIONS FOR SURVEY OF THE COMPASS ROSE

INTRODUCTION

The purpose of these instructions is to provide a standardized procedure

for making a magnetic survey of a compass swing area, using the MC-2 Compass

Calibrator. It is expected that the technical judgement be exercised through-

out the survey as it may require that methods be altered to fit the circum-

stances of a particular case.

DESCRIPTION OF COMMON PROCEDURES AND TERMS

1. Grid - A pattern of required test stations, laid out to cover the compass

swing area.

2. Station - A grid point or hub mark at which magnetic readings will be

taken (See Grid Layout Sheet).

3. Set Up - When directed to set up over a station, precisely position the

tripod, with the required unit, directly over the station indicated by using

the plumb bob, and accurately level the unit.

4. Mark the Station - The precise point of the station may be marked with a

felt tipped pen, china marking pencil or any other method which will permit

set up to within two millimeters of the correct position. These marks may be

made directly on the hardstand, a piece of masking tape applied to the hard-

stand or on top and the face of a short 1X2 stake driven into the ground at

the proper position. These stations shall be accurately positioned by using a

steel tape to measure the distance between stations as determined. The dis-

tances between adjacent stations shall never exceed thirty (30) feet; however,

this distance can be reduced to allow more complete coverage of a particular

area. The marks shall be accurately aligned with the cross hairs of the

telescope by moving the telescope elevation ONLY.

5. Hub - Preferably a stake positioned at the north, south, east and west

points of the compass swing area, at a distance of approximately 300 feet from

the center. It shall be marked on the top of the stake as well as the face of

the stake toward the center.

6. Azimuth Control - Reference mark, preferably on a stake, positioned a

minimum of 300 feet in the north direction from the E-W line of the compass

swing area. It shall be marked on the face of the stake to allow accurate

alignment of the telescope cross hair when performing a setup for magnetic

readings.

GENERAL PROCEDURE

1. To conduct a magnetic survey of a compass rose, it is first required that

a grid which will completely cover the area, be accurately laid out.

Enclosure (2) is the Grid Layout Procedure which gives step-by-step

instructions for laying out the grid using the MC-2 monitor. This procedure

Enclosure (1)