Thursday, 21 May 2015



Anglers are somehow just naturally gadget obsessed, but do many actually know and understand their sonar sounders? This is part 3 of my set of articles outlining all aspects of sounder settings to optimize your fishing abilities and open up a whole array of technology questions and have them explained in simple detail. Some gadgets can end up being a burden of nothing better than a purchase that was not nessesary, or a case of "Catching you with your wallet open, rather than catching any of those finned foes". But some gadgets actually end up working in a way that you could never have imagined, mainly due to the fact you have never been explained the in and outs of it in order to actually properly use it to a degree as to when it actually starts assisting you, and Structure Scan HD is actually one of those "Gadgets"


Lets take a look and break down all that is Side Scan Sonar Imaging, this function I consider to be one of my most important features of my sonar unit as a lot of my Bass fishing is done casting into the snags alongside the rivers edges and banks. Side scan capabilities allow you to have a far greater side-to-side range of imagery for marking fish and structure along side your boat as opposes to standard sonar 2 dimensional imaging. Sonars work using echo sounds, which is a form of active sonar, an electrical signal that is sent from the sounders transducer that's then converted into an acoustic pulse. Your standard  sonar broadcasts this pulse usually in a downward action to the seabed floor and then back up to the transducer that then converts it into an image on the screen in either 50kHz, 83kHz or 200 kHz. But Structure Scan HD uses a high frequency of either 455kHz or 800kHz for much larger cone angles and bigger frequencies allows the unit to return with greater detail.
Side scanning is not scanned downward, it is scanned to each side of your vessel right up into those snags and banks to return a much more vivid image of fish and structure that are likely to hold suspending fish.

Every waterway has bumps, channels, edges and other structure located that typically hold fish. Side scanning sonar will allow you the ability to approach these key structural places and scan them so now time is wasted in casting into structure or structure less bodies of water rather than blind casting. You can also determine the exact depth by moving the cursor over the marked fish or structure  making sure your lure is directly in the strike zone, this is the biggest game changer of all. Everyone loves to see surface feeding, This type of fishing is the most exhilarating style of angling any fisherman can ever do, with side scan you can view which side fish move to when the go deep so you can determine which side to cast before they re surface, yet again getting your lure into the strike zone every time. Many times I've been able to stay with active schools long after the fleet have given up returning to the surface with hookups time and time again without ever visually spotting the fish again.

Side scan sonar capabilities give you a far better and longer range as it projects well beyond the limitations of traditional standard sonar transducers. Side scan will allow you to scan both sides of the boat or in the settings you can change it to just one side of the boat. You can set your device to only scan in the shallows which will allow you to to set the range well over 100 feet to the side and still make out important detail. You can scan Weed beds and lines, sunken vessels, natural reefs, coffee rock or fallen trees, the limits are endless.

Identifying fish, I usually primarily target bass in the warmer months, on traditional sonars you will see bait marked as a red blob (Depending on your sounder settings) and this allows you to notably view them as a rather blurry image that's under your boat. You can then begin to make an educated guess based on the water temperatures and ;location of the size of the school of bait. Side scan solves most of this guesswork for you, Take some bait fish for example.... white bait usually school in congregations of around 100 to 200 individuals and look like a loose ball of white dots, but Kingfish typically appear in schools of around 10-20 and above in offshore reefs in tightly packed schools. I may not seem like  much, but to the trained eye it becomes much more obvious as to what that type of species may be.

I explain Side Scan Imaging and how it actually scans the sides of the vessel as a folded piece of paper in the middle leave the sides of the paper laying flat. The top edge of the paper is the boat, and it scans out to the sides as well as in a downward motion, allowing the area to be completed covered to your desired depth setting.


To easily grasp the concept of Down Scan HD Imaging, think of it as a detailed high definition digital television as opposed to the old analogue tuners (Some younger readers may not remember those days) It creates a much greater detail in images than the standard sonar image, the signal is much more intensified to create sharp, crisp and high definitive imagery on your HDS screen. Lowrance HDS Broadband units allow bottom soundings of up to 600 fathorns,

Down scan imaging has the ability to provide a greater detailed picture-like image of the bottom and structures directly below your vessel. acting exactly like the down scan version of side scanning. These picture like images displayed on the screen use a specific image software that represents the return sonar signal in the most detailed manner. The 455 or 800kHz frequencies used in Broadband Imaging gives the sharpest image of resolution where as the 455kHz frequency gives the best overall image quality and depth. As I've explained in a previous article on frequencies on this website in the past

Broadband scan not only gives a better cone of detail than a standard sonar can give, but it will generally pick up fish in areas a standard sonar usually would return an image detailed enough to show fish sitting on the edges of drop offs like Mulloway and Flathead. But standard sonar will always still have its place in modern fishing as it gives off contrast for bottom hardness and vegetation and tuned right will assist any angler when combined with both Structure Scan functions, which is when Overlay Down Scan imaging comes out to play.


The exclusive technology of Overlay Down scan option allows you to combine both standard Sonar Imaging and Structure Scan HD Imaging to get the best offers from both worlds. This easily exposes fish targets from structure with fully adjustable palette options available. 

Separating fish from structure using the Overlay Down Scanning if used in the right situation can be one of the greatest tools in angling history. Many times fish have been sitting inside structure and are hardly visible as fish on the screen, this take the guess work away by allowing the structure and the fish to be viewed both in a totally different way. the fish will be scanned in 2D and the structure will be viewed as 3D making it so much easier to make that targets visible amongst the heavy dense cover.

For those of you that don't have the luxury of having a larger screen to easily run both Structure Scans and standard Sonar displays on the one screen then overlay down scan can be a great option for you. You can also adjust the transparency of the overlay in your options to suit your viewing discretion. The idea behind down scan Overlay is to better your view, example being is... If your fishing in an uncharted area with no means of whats below, your likely to see rocks and other fish holding structure a lot better on Structure Scan HD than you would on standard Broadband Sonar as it would most likely return an image that you cannot define any detail. With both imagery combined and layed over the top of each other its a much easier way of viewing suspending fish amongst easily distinguished structure. It can take a little getting used to, but try and see bottom with Structure Scan, image overlaid on the Broadband Sonar and pick out the fish on the screen with the broadband sonar image that is incorporated over the top. 

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