DAVIS Parallel Rules User 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 [phone] • Fax [phone]

[e-mail] 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.