DAVIS Parallel Rules - Manual

INSTRUCTIONS
#061
Parallel rules are the most basic plotting instrument.
Davis Parallel Rules are completely transparent with
a clear optical finish for exact plotting. Each 15" (38
cm) blade features large, easy-to-grip handles.
Precision molded for the most accurate straight line
plotting money can buy. All Davis plotting tools feature
sharp printing process, high gloss finish on front and
back, and overlamination for durability.
To Measure Course Bearing:
1) Place outer edge of one rule on the course line.
Holding that rule down firmly against the chart,
swing the second rule out away from the first.
2) Hold the second rule firmly against the chart and
swing the first rule up to meet it.
3) Alternately holding and swinging each rule, “walk”
he rules across the chart to the nearest compass
rose.
4) With the outer edge of one rule at the center point
of the rose, read the bearing at the rose.
PARALLEL RULES
3465 Diablo Ave., Hayward, CA 94545 U.S.A.
Phone (510) 732-9229 • Fax (510) 732-9188
[email protected] www.davisnet.com
061_Inst. pdf October 2005
To Draw a Course or Bearing from a Given Point:
1) Place the parallel rules on the chart so that the
outer edge of one of the rules passes through both
the center point of the compass rose and the
desired bearing.
2) “Walk” the rules across the chart as above until the
outer edge of one of the rules passes through the
given point. Draw the line against the edge of the
rule.