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Hummingbird Fish Finders - Understanding Side Imaging and Down Imaging

Updated on May 14, 2013

Having Problems Understanding the SI and DI Display of Hummingbird Fish Finders?

To have one of the SI Hummingbird Fish Finders on your fishing boat not just as a tool for finding fish but to use as a navigational tool, is really a huge advantage.

Even if you haven't been in a certain area for fishing before, based on the Side Imaging and Down Imaging captions of a Humminbird unit, you will be able to easily examine broad chunks of water from side to side your boat and find the big fish rapidly.

It usually takes quite some time, even a couple of hours to locate a good fishing spot. But with the Side Imaging system incorporated in the top Hummingbird Fish Finders, you can do that in minutes.

However, my aim for writing this report is to put into view how the Side Imaging and Down Imaging technology works, and how to understand the images that will materialize on your screen in SI and DI mode.

Hummingbird Fish Finders - How Does Side Imaging Work

A standard sonar utilizes a cone beam to "look" in a straight line under your fishing vessel. SI sonar casts two slim beams, one on each side of the vessel, in a 180° beam under the it. It covers a distance up to 240 ft on each side of your vessel. So, you will benefit from a 480 ft sight of what's going on in the waters you're fishing, ou will be able to see clearly what objects are in the water, where exactly is their position in relation with your boat, and most important where the big ones are.

If you didn't know, the best Humminbird units endowed with Side Imaging are the ones in the 1100 and 900 series. I personally recommend the Hummingbird Fish Finder 1198c SI Combo. It has all the options and features that a superior fish finder, chartplotter and marine GPS unit should have. With a unit like this, your boat will be complete.

Significant to know here, most Hummingbird Fish Finders that have Side Imaging features also have DualBeam Plus sonar. This sonar normally works for waters of 1500 ft depth. However, the readability of Side Imaging is available only down to about 200 ft depth. In waters deeper than that you will have to work with the SwitchFire mode of the sonar.

Hummingbird Fish Finders - How to Read the Images Shown in Side Imaging Mode

In the circumstances you just got one of the Humminbird Fish Finders with compatible with Side Imaging, it will almost certainly take some time until you will become completely familiarized with it, and be able to interpret the the returns properly. I in fact became able of understanding the images properly only after my third fishing expedition on the same lake, already knowing what's sunken there.

However, with a little bit of rehearsal, understanding Side Imaging is quite straightforward. Your fishing boat is at the top of the monitor, so essentially the whole is formed behind your boat. The darker section in the middle of the screen is the info of the sonar beams as they travel through the water, before they reach the bottom.

Structures, fish, mounds and ditches on each side of the vessel will materialize in superior detail.

Rising terrain or hard bottom terrain appears lighter on your screen, while fallen terrain like underwater ditches, or softer terrain will appear darker.

You will see that various objects cast certain sonar shadows. The longer the shadow, the taller the object.

Fish show up on your screen, in Side Imaging mode like spindle-shaped objects, and balls of bait fish are shown as clouds. Fish also cast a sonar shadow, so the farther the shadow from the fish, the higher in the water the fish is positioned.

Anyway, to see better where they are, it's best to move the boat above them and have a look with the Down Imaging mode.

Nearly all Hummingbird Fish Finders that have Side Imaging and Down Imaging also have the customary 2D sonar imaging. So, by switching all three types of imaging, or observing all three views in split screen, you will be able to find a good fishing spot in minutes and start fishing, while others are wasting their time wondering where the fish are.

In conclusion, why throw away your time searching for fish, when you can locate the big fishing game in a very short time?

Hummingbird Fish Finders are the best equipment for finding fish, and most of them can be utilized as trustworthy marine GPS devices, giving you a wide range of benefits.

Ok, now let's take a look at the Hummingbird Fish Finders Down Imaging technology.

The truth is that Hummingbird Fish Finders with Side Imaging technology are more reliable than the ones which have only Down Imaging. However, once you become accustomed to the Down Imaging returns, a fish finder that has only the DI feature can be as reliable with one with SI.

Anyway, I'm writing this report to explain in a few words how Down Imaging sonar works and how to interpret the images displayed by the Hummingbird Fish Finders DI returns.

How Does the DI Sonar Work?

The transducer sends a sound beam into the water and every time it hits a structure, a fish, a rock, a tree or the bottom it, sends back an echo, and the reflection of that echo will appear on your screen. It basically works as the SwitchFire display, but with the accuracy view of the Side Imaging technology. Down Imaging shows everything that is directly under the boat, which Hummingbird Fish Finders that have this technology ideal to measure the dimensions of an underwater structure, a sunken tree or exactly how deep is a fish situated.

Just so you know, one of the best fish finders from Humminbird which has only Down Imaging is the Hummingbird Fish Finder 788ci HD DI Combo. So, in case DI is enough for you, the unit I just mentioned should fit perfectly to your needs.

How to Interpret the Down Imaging View

Without Side Imaging it will be a bit harder to interpret the Down Imaging returns. On the DI display, the boat is placed on the upper right corner, at 0 coordinates, and the image is actually formed behind the boat, where the transducer is mounted. You should always mount it there.

Objects that will be "cut" by the sonar beam will appear on your screen, you will clearly see their shapes, and you will be able to distinguish what exactly they are. Trees, for example, or any other dense shapes, will appear very distinct compared to the SwitchFire mode. However, you won't know exactly on which side of the boat a certain object is, and you will have to make an estimation.

Just as in Side Imaging mode, bait fish appear like clouds or high concentrations of "noise". Bigger fish, the ones that you should target, show up on your screen like spindle shaped objects.

Down Imaging is quite reliable for measuring depth. It allows you to measure accurately how deep is every ditch, or how tall stands every mound that passes under your boat. Also, if you fish in waters with a high concentration of vegetation, you will understand perfectly where to cast, to avoid losing your lures in the aquatic flora.

Anyway, most of the Hummingbird Fish Finders have both Side Imaging and Down Imaging, and combined with the SwitchFire display mode, you will basically have 3 views of the underwater world. This way you will be able to locate a hot fishing spot quickly and target only big ones. Also, you can view only the SwitchFire and DI in split-screen.

So, are you looking for a tool that will maximize your fishing experience?

Best choice: The Hummingbird Depth Finders with both Side Imaging and Down Imaging. The best 3 fish finders from Humminbird are:

1. The Humminbird 1198c SI Combo. This is at the moment the best fish finder from Humminbird. It features quite a big screen of 10.4 inches in diagonal, 600x800 resolution, with LED backlight which means that you'll benefit from an excellent readability of the screen even in direct sunlight. It has chartplotting, trackplotting and GPS... read more here.

2. The Humminbird 998c SI Combo. It's a smaller fish finding unit than the 1198c SI Combo, the screen having only an 8-inch diagonal with a pixel resolution of 480x800. Other than that, has all the features of the 1198c SI Combo model, however the screen dimension difference makes it considerably cheaper than the 1198c SI Combo. In fact the 998c SI Combo is at the moment the SI and DI fish finder and chartplotter with the best price/quality ratio... read more here.

3. The Humminbird 898c SI Combo. Similar to its superior brothers, the 1198c and 998c, this fish finder has almost the same effectiveness and features, only the head unit is a bit smaller than the 998c SI Combo, the screen having only 7" in diagonal, however, the resolution is the same as for the 998c, 480x800. Has basically the same features, GPS, chartplotting, trackplotting, DualBeam Plus sonar... read more here.

All 3 fish finders mentioned here, along with the 798ci HD SI Combo are compatible with the new Humminbird 360 Imaging. Find out more about this new type of sonar, below.

Humminbird 360 Imaging

In September this year, Humminbird is going to launch a brand new type of sonar, the Humminbird 360 Imaging. This type of technology is similar to the Side Imaging, but instead of showing you what's on the sides of your boat, it provides a 360° image of the bottom, the circle having a radius of 150 feet. This new system is compatible with the best Hummingbird fish finders with ethernet, in other words, with the 798ci SI Combo, 898c SI Combo, 998c SI Combo and 1198c SI Combo.

Humminbird 898c SI Combo - What's in the Box

I never thought of posting a youtube video with unboxing a product, but videos like that are quite informative, and help people understand better what they pay for. Therefore, the next video (although not mine, it was made by An angling and you can subscribe to his channel if you want), shows exactly what's in the box of a Humminbird 898c HD SI Combo. Enjoy!


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