Vexilar Flasher Family 2013 - Manual (Page 51)

51
Dead Zone
Beam angle has a large effect on the
performance of your flasher. There is more to
it than simply area of coverage. The correct
beam angle to use depends entirely on your
application. If you are fishing for suspended
fish then you would be pleased with the
performance of the 19° cone. However, if you
were going after fish that are holding right
on the bottom along a steep drop-off, you
would have better
results with the 9°.
This is because of
something called
dead zone. Dead zone is an area within the transducer’s cone
of sound that is blind to you. The wider the beam angle the
greater the possible dead zone. The sonar will mark bottom as
the nearest distance it sees. If you are fishing over a slope, it
may see the high side of the slope, at the edge of the cone, and
mark that as bottom. The fish that are holding on the bottom on
the low side of the slope will be invisible to you because they
are actually within the bottom signal on your depth finder. A
narrower beam angle will reduce this effect.
Output Power
Your depth finder puts out a constant amount of power, or sound energy. It does not
matter where you have the gain level set. Gain simply controls how much you amplify the
signal that is returned from below. Therefore, a narrow beam transducer will appear to be
much more powerful than a wide beam transducer. This is because you are putting that
same amount of power into a smaller area. This can be an advantage if you are fishing in
deep water or a detriment if you are fishing in shallow water. A narrow beam transducer
can be overpowering in shallow water. The use of the LP (Low Power) mode on your
flasher, or the optional S-Cable (page 56), will solve this problem.
Remember to NOT use LP mode or the S-Cable in depths beyond 20 feet. You will find
that you need to turn your gain control up much higher than normal. This will give a noisy
display and make interference from other units much more likely.
Cone angle vs
Diameter of Coverage
d
epth
8° 9° 12° 19° 20°
10’ 1.4’ 1.6’ 2.2’ 3.4’ 3.5
20’ 2.8’ 3.2’ 4.3’ 6.7’ 6.9
30’ 4.2’ 4.7’ 6.3’ 10.0’ 10.6
40’ 5.6’ 6.3’ 8.4’ 13.4’ 14.1
50’ 7’ 7.9’ 10.6’ 16.7’ 17.6
60’ 8.4’ 9.4’ 12.6’ 20.8’ 21.2
70’ 9.4’ 11.0’ 14.7’ 23.4’ 24.7
80’ 11.2’ 12.6’ 16.8’ 26.8’ 28.2
90’ 12.6’ 14.2’ 20.0’ 30.1’ 31.7
100’ 14’ 15.7’ 21.0’ 33.5’ 35.3
120’ 16.8’ 18.9’ 25.2’ 40.2’ 42.3
150’ 21’ 23.6’ 31.5 50.2’ 52.9