by Bruce Middleton, November 06, 2006
The new generation of side looking sonar’s…
I suppose the average American if you ask them what sonar is they would instantly think about the navy, a big round screen in a darkened room with a white bar going round and round kind’a like a radar unit. But to fisherman a sonar unit is a tool, a flat screen that gives him the depth of water he is in, the temperature of that water and a rough idea of what the bottom contours look like in a running strip chart type style.
Now on the bigger commercial fishing boats where they have sonar, and strip chart recorders, they have a much better idea of what the bottom looks like because of the resolution of the gear they have installed. But when you get down to the hobbyist or even the professional fresh water fisherman, this type of equipment would literally sink our boats it’s so big and heavy. So we have a fully a different class of depth/fish sounders to cover our needs. They are small and light and for the most part give a pretty good idea of what is going on under the boat.
Depth/fish finders are one of the most important tools for the angler today, no matter what species of fish you are fishing for. Basically a sounder or sonar unit is a speaker, a microphone and a stopwatch. The speaker puts out a pulse or sound wave and a microphone picks up the returning echo. The stopwatch times the whole event.
A sound pulse is sent out and then this returning sound is transformed into an electrical signal and this signal is displayed on a screen. This signal is generally poor in quality and leaves a lot up to individual interpolation. Some people say they can interpret temperature gradients while others can’t. Some see fish while others see noise. Improvements were desperately needed to remove this type of guesswork and to provide a clear and concise picture that everyone could agree on with a single glance. You have to be able to understand what is being displayed on the screen before it is of any use to you.
Now with advent of color monitors it’s easier to discern features on the screen but a lot is still left up to individual interpolation. Some sonar unit’s use and extra beam to provide the extra clarity that a color monitor needs to function correctly while others use 2 or more beams. This is all in an effort to make reading the final output, the screen as easy as possible and as universal as possible with as little misreading as the manufacturer can make it.
But now the new side scanning sonar is on the market and it promise to make all of our dreams of seeing what is on the bottom and what a wide area of the bottom looks like on picture quality flat screen format. But in order to under stand the new technology, you must first understand the old and the steps it took to get to the new.
Single beam sonar is pulsed to give you the best view of fish, structure and cover on the bottom from a down looking unit. It is not a wide beam but what you get is a great picture of what the bottom looks like so you can see what structure and cover the fish might be using for concealment.
A duel Beam Plus ™ sonar unit uses a narrow focus center beam surrounded by a conical second beam of about 60 degrees to expand it’s coverage to an area equal to that of the depth. So if you’re in 20 feet of water the screen will show a 20-foot area of the bottom, still from a downward point of view. The first beam is focused on the bottom to show you structure, weeds and cover while the second beam is searching for fish in a wide coverage area. Now while it is possible to use the second beam only, it is less effective because you have no reference to the bottom and therefore you don’t know the depth of the fish.
A Wide Side ®sonar does just what it’s name implies, but it uses three (3) beams or pulses to accomplish it’s goal. The first beam is a narrow beam at about 24 degrees looking down while the other two beams look directly to the left and right out about 160 feet. This is an incredibly wide field of view to scan for fish. Remember the second beams only see fish. This is an outstanding choice for looking under docks, bank cuts and along shorelines. You can see everything without having to get actually drive your boat anywhere near the object you wish to see under.
3D Plus™ sonar uses six (6) separate beams to look at the contours and slopes of the bottom for and expanded on-screen view 3D display which shows clearly, every little detail. The six beams provide 53 degrees to continuous coverage up to 240 feet to the side. New 3D systems actually measures the depths between the beams for a total of 11 discreet depths. With this unit you can see things like a wooden pallet or the entire underwater creak channel or an underwater roadbed, all in a single pass where other units would take four or more pass’s to accomplish the same feat.
Side Imaging sonar or what some are calling the new Side Scanning sonar gives you the best of all worlds. It is the newest of the technologies and the highest resolution one. It gives you near picture perfect like view of the bottom and structure so you can analyze it like never before. This will help you become more efficient and more effective on the water. Two very precise and very wide but narrow front and rear sonar transducer sonar beams are directed to the sides to illuminate the bottom, fish, structure and cover to give you thin slices for extreme resolution. These slices connect, giving you a picture like image with unbelievable detail. This new sonar system can see 240 feet to each side in 100 feet of water or 48 feet to the side in 20 feet of water. The forward and aft configuration of this system covers a huge area at once yet you can discern a bottle on the bottom even if it is lying on its side.
Side looking sonar is more than regular sonar transducers pointed at an angle instead of straight down. This is a whole new technology. This new side scanning sonar operates basically on the same down looking principles as all sonar’s, with two important differences. Firstly, a side looking sonar sends out and retrieves sound waves out of the side of the boat rather than just straight down. And secondly it is especially programmed to ignore structure with the second beam and only display fish on the screen. With a side scanning sonar you’re always looking for and at fish, with the bottom showing as a reference point. Some of the smaller bottom of the lien units won’t show fish less than 7 inches long so bait fish schools never show up. This is not a good system to own, as baitfish are an important part of game fish habitat.
How many fish have you missed because you couldn’t see that they were just thirty feet to the left or right of you while you were fishing a good lake? How many wasted casts did you spend on a docks with nothing under them or how many docks did you give up on too soon. This new sonar system will let you know if you are in a barren section of a grass flat or if another bass is under the dock you just caught one under.
Of the two different Hummingbird sonar units I personally have looked at, the Hummingbird 987c SI and the enhanced 987 with GPS, I can say this: WOW! The picture of the bottom is as if you had drained the lake and were sitting about 20 feet up in the air above it. There wasn’t anything that was hidden and there was no detail too small that didn’t show up. The only downfall now however, is the price. The Hummingbird 987c SI is $1799 and with enhanced GPS unit add its $1999. In my book this is not cheap. Personally if I had an extra $2000 dollars it would the down payment on a new bass boat. But that is different story. Eventually the price of electronics will go down. And in a few years from you will be able to pick one of these units up for a few hundred dollars and I can hardly wait for that day to come. These new toys are going to revolutionize fishing, as we know it. The pros will use them first, of course, and the popularity will increase as the prices drop. Soon everyone will have one and we will wonder how we ever got along without such a device.
Bruce Middleton
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