Bushnell MARINE Manuel page 4

How to use the reticle to measure distance
The distance measurement of a target can be calculated by using the mil reticle. Refer to the example in Fig. 5 above.
The formula for distance measurement: L(km)=H(m)/w
L= the distance between the observer and the target (in kilometers).
H = the height of the target (in meters)
w=upper and lower angle of azimuth of the target measured with the binocular reticle (mil).
When measuring the distance, first, estimate the height or width of the target, then measuring upper and lower angle of the target.
Accordingly, you can calculate the distance between the observer and the target using the formula.
For example:
There is a lighthouse whose height is known to be approx. 30 m. (H=30)
The upper and lower angle of the lighthouse as measured against the reticle in Fig. 5 is 0 – 60 mils (w=60)
So, using the formula: L=H/w=30/60=0.5 km
Therefore: the distance between the observer and the lighthouse is 0.5 km.
How to measure a target's size (height and width) using azimuth readings
According to the formula for distance measurement, you can calculate the height using: H = D x w. When measuring the size,
you first estimate the distance to the target, then measure the azimuth or upper and lower angle. With these measurements, you
can calculate the height of the target using the formula.
For example: the distance is 0.6km between the observer and the target. You can measure that the azimuth is 60 (0-60) and the
upper and lower angle is 30 (0-30). So, using the formula you can get:
The height: H=0.6 x 30=18m
The width: h=0.6 x 60=36m
How to use the compass
The azimuth angle can be also measured through the compass built into the right half
of the body . It shows the azimuth of the object vis-à-vis the observer. Each graduation
of the compass equals one degree of angle. When the object lies in the north from you,
the compass shows 0°.And it will increase when you turn clockwise. 90°means the
object lies in the east from you, 180°means the south and 270°means the west.
In order to insure precise angle measurements, the binoculars should be kept horizontal
and level when reading the compass. The object should lie in the middle of the
reticle.
The graduations of the compass need to be illuminated for convenient viewing when
there is not sufficient daylight to illuminate the compass dial. (Do not use the battery
operated internal illuminating system when the outside viewing conditions are bright
enough to see the compass dial and marking clearly.)
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Fig. 5