Sonar in shallow water

[cpierce]

How well does different brands of sonar work in water that is from 5 to 15 or 20 feet deep? Is there a difference in shallow and deep water function?
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[flygoddess]

I would think yes. Isn't the beam a CONE, which would mean, the deeper the water the bigger the cone, the more area it would cover. As far a reading a fish right infront....then no I wouldn't think depth would matter.

All I know, if I am in shallow water, it is more a visual than a sonar thing.
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[TubeDude]

[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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[cpierce]

So is the Hummingbird 565's 60degree cone about the same as a sidefinder? Can you tell what direction the fish are from you -- to the right or left side, in front or behind you?

I fish a number of small res. that generally have trout, but also many have perch, bluegill, crappie, and bass, but usually the maximum depth is maybe about 20 to 25 ft.
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[TubeDude]

[cool][#0000ff]The 565 cone is not "directional". It shoots straight down. And, it is not practical to move the transducer around to try to create a "sidefinder" application. It needs to shoot straight down and have a bottom at a 90 degree angle. Won't work otherwise.[/#0000ff]
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[#0000ff]The 60 degree cone is still a cone, but a wider one than the regular 20 degree cone. And it only works when in the Fish ID mode. Fish within the 20 degree cone display in solid black. Fish outside the 20 degree cone but inside the 60 degree cone display as outline only.[/#0000ff]
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[#0000ff]I believe the Humminbird PiranhaMax units have some directional fish location capability.[/#0000ff]
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[#0000ff]True side finding technology is usually pretty pricey but there are some mid range units that can do that.[/#0000ff]
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[#0000ff]Most of the waters I fish for trout and non trout species are less than 25 feet too. With the exception of suspended trout, I can usually find the fish just fine. In fact, most of the non trout species are structure or bottom oriented. About the only time my sonar has problems with the display is while I am going out through the first five or six feet of water. Once I get into at least 6 or7 feet I get a good display and the fish show up too.[/#0000ff]
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[tlspyder13]

I have the Humminbird 575. It is the same as the 565 but with side sonar. When you are using the side sonar the screen is split in three. It shows below you, to the left and to the right. You can't tell which way the fish are swimming but you can tell what side of you they are on.
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[cpierce]

Thanks all!! I am still debating and looking for what will work best for me. Having some information on the different models from users sure helps.
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