Thread: settings on 1197si

Originally Posted by Humminbird_Greg

Rnvinc,
Depends on which you are meaning here: the 2D or Si frequencies.

For the 2D frequencies the 200kHz will be the higher frequency and due to the shape of the element inside the transducer that produces this frequency it has the narrower cone angle. At the -10db point it is approximately 0.35 times the water depth. So at 10 feet deep the beam will be about 3.5 feet wide and in 50 feet of water it will be about 17.5 feet wide. That means that the beam is only covering 1.75 feet out to each side of the transducer when in 10 feet of water (half the width of the beam) and only 8.75 feet out to each side when in 50 feet of water.
The 83kHz beam is the lower 2D sonar frequency and has a wider beam due to the shape of the element inside the transducer. At the -10db point it is approximately 1.0 times the water depth. So at 10 feet deep the beam will be about 10 feet wide and in 50 feet of water it will be about 50 feet wide. That means that the beam is covering 5 feet out to each side of the transducer when in 10 feet of water (half the width of the beam) and only 25 feet out to each side when in 50 feet of water.

The Si frequencies are a little different. The higher frequency is the 800kHz beam and it only covers an area about 72 degrees. The 455kHz beam may be the lower frequency beam but due to the shape of the element being used it is the wider beam at about 86 degrees. Now even though these beams were measured in a lab at the -10db point what we have found through usage (and users have confirmed) is that the 455kHz Si beams effective cone angle (what you would experience during usage) is far wider as many can confirm that they in fact overlap.
The maximum Si sonar range will depend on several factors like the water quality, whether anything is blocking part of the Si sonar, wave conditions and the actual water depth. Usually its hundreds of feet.

Greg and Jason, you are definately a wealth of information and I appreciate your willingness to help....

Does each sonar feature (2D, DI and SI) have it's own separate element inside the transducer so that the sonar frequency of each (2D, DI and SI) can be set individually..??