6
DIVER MAG 1 DETECTION RANGE CHART
OBJECT
NEAR RANGE
FAR RANGE
1 gal can .......................................................................................................... 2 gamma 12'
5 gal can .......................................................................................................... 2 gamma 18'
55 gal can ........................................................................................................ 2 gamma 45'
Sm. Plane ........................................ 25 gamma at 20' .................................... 2 gamma at 50'
1 ton iron.......................................... 40 gamma at 30' .................................... 2 gamma at 80'
6" pipeline ....................................... 200 gamma at 20' ................................... 2 gamma at 100'
12' pipeline ...................................... 350 gamma at 20' ................................... 2 gamma at 175'
Lg. anchor ....................................... 500 gamma at 50' ................................... 2 gamma at 200'
Med. ship ...................................... 1500 gamma at 100' ................................. 2 gamma a 1000'
Lg. ship ......................................... 2000 gamma at 100' ................................. 2 gamma at 1500'
The above chart shows the Diver Mag 1 detection range for different targets. The Diver Mag 1 has a sensitivity of one
gamma; that is, it will detect a change of one gamma. Each one gamma change will change the digital readout one
digit.
CHART EXAMPLE:
As the Diver Mag 1 approaches a small plane, you can expect a one gamma change at 65-75' (the digital readout
would change one digit, ie: from 48,240 to 48,239). At 50' distance, another one gamma change would take place (ie:
48,238 on readout). As the fish gets closer, the readout continues to decrement. At 20', you can expect the readout
to be at 48,215 (total change of 25 gamma). As the fish passes next to the plane the digital readout could be several
hundred digits lower. If the target was 1 ton of iron, the readout could show a change of 2,000. As the fish goes past
the target, the readout would walk back to normal (48,240) in reverse of the above sequence.
As a target is approached, the gamma reading can change up (increment) or down (decrement) depending on what
is happening to the magnetic field in the area. It is not unusual, when making many passes in different directions over
a target, to find some passes incrementing the readout number and other passes decrementing the number. In most
cases, when you approach a target, the gamma number will drop as shown in the example above.
The detection ranges given above are standard magnetic deviations for different size targets. You can expect the
distances to vary depending on the area you are working. If it is in a noisy area (on land or just off shore) small
magnetic changes will be more difficult to discern.
