12-21-2009, 12:31 PM
[cool][#0000ff]Can't really give a breakdown by make and model, but as a general rule it is a matter of power and adjustment. The lower the wattage the less discrimination accuracy and the more false readings you get...especially in water shallower than about 10 feet. If you have a unit that has adjustments for tuning out surface clutter and water borne items like bubbles and algae you can usually get a reading on most of the fish.[/#0000ff]
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[#0000ff]It has been my experience that any sonar with less than 1000 watts of power does not work well at all in shallow water. The Eagle Cuda line, for example, is prone to showing lots of false targets. I have had it in 8 feet of crystal clear water and it showed random fish signals even when I could clearly see there was nothing below me.[/#0000ff]
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[#0000ff]And, as has been mentioned, the type of transducer you have can make a difference too. Some sonars only have a 9 degree cone angle. Most have something around 20 degrees. As a good rule of thumb, the "footprint" of the cone will be about 1/3 of the depth, with the 20 degree cone. That means that in 10 feet of water the cone will be about 3 feet at the bottom and much less in between. A sonar with only a 9 degree cone will not pick up very much at all and is useful mostly as a depth finder.[/#0000ff]
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[#0000ff]I have the Humminbird 565 which has a dual cone transducer. One cone is 20 degrees but the other is 60 degrees and picks up fish that are nearby but not within the 20 degree cone. So far I have found it to be very reliable and have been able to catch quite a few fish that were displayed on the bottom, even concealed in weeds.[/#0000ff]
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[#0000ff]For those who enjoy fly fishing for trout, a sonar with a "side finder" option can be very helpful. It allows you to locate fish cruising nearby that would never swim directly under you to register on a "standard" sonar. Trout, crappie and some other species are more likely to swim suspended above the bottom so they may be more difficult to find with "lookdown" sonars.[/#0000ff]
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[#0000ff][/#0000ff]
[#0000ff]It has been my experience that any sonar with less than 1000 watts of power does not work well at all in shallow water. The Eagle Cuda line, for example, is prone to showing lots of false targets. I have had it in 8 feet of crystal clear water and it showed random fish signals even when I could clearly see there was nothing below me.[/#0000ff]
[#0000ff][/#0000ff]
[#0000ff]And, as has been mentioned, the type of transducer you have can make a difference too. Some sonars only have a 9 degree cone angle. Most have something around 20 degrees. As a good rule of thumb, the "footprint" of the cone will be about 1/3 of the depth, with the 20 degree cone. That means that in 10 feet of water the cone will be about 3 feet at the bottom and much less in between. A sonar with only a 9 degree cone will not pick up very much at all and is useful mostly as a depth finder.[/#0000ff]
[#0000ff][/#0000ff]
[#0000ff]I have the Humminbird 565 which has a dual cone transducer. One cone is 20 degrees but the other is 60 degrees and picks up fish that are nearby but not within the 20 degree cone. So far I have found it to be very reliable and have been able to catch quite a few fish that were displayed on the bottom, even concealed in weeds.[/#0000ff]
[#0000ff][/#0000ff]
[#0000ff]For those who enjoy fly fishing for trout, a sonar with a "side finder" option can be very helpful. It allows you to locate fish cruising nearby that would never swim directly under you to register on a "standard" sonar. Trout, crappie and some other species are more likely to swim suspended above the bottom so they may be more difficult to find with "lookdown" sonars.[/#0000ff]
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