When you’re out on the water scanning with your down image you have the options of using the 455 kHz or 800 kHz setting on my Humminbird Onix. In the photos I’ll show you what you are missing if you are not using the correct setting. When you are in deep water you need different setting than when you are in shallow water. With the Humminbird Onix the 455 kHz setting is using two 86 kHz beams at once which covers 172 degrees. While the 800 kHz setting use two 55 degree beams that only cover 110 degrees total. So you can see that the narrower beam does not reach out as far as the wider 455 kHz setting.
With the 2D or sonar beam you have a choice of either the 20 degree or the 83 degree cone or a combination of both. You need to remember that with the 2D sonar cone set to 20 degrees you are only scanning 1/3 the depth of the water. In other words if you are in say 9 feet of water you are only looking at a 3 foot circle under your boat. With the 83 degree setting you are covering an equal area to your depth. If you are still in the 9 foot of water you are scanning a 9 foot circle under your boat. For the best scanning I’d suggest you a combination of both the 20 cone and the 83 degree cone.
Now let’s look at the photos a second. The photo above I have the setting set to 455 kHz with a wide beam selected. In this can I am in water that is less than 10 feet deep and you can see I can scan a very wide area out from my boat.
Now in this photo I have my unit set to 800 kHz with a beam wide setting which only covers 110 degrees out from both sides of the boat. I’m still in about 10 feet of water or less. As you can see you can’t see nearly as much detail as in the photo above set to 455 kHz.
Now let’s look at the down image scan while I’m scanning in water around 30 feet deep in the photo above. I have the unit set to 455 kHz and I’m covering 172 degrees under the boat. The fish by the way are stripe and shad. As you can see there are rocks close to the shore line.
Finally in the above photo I have the unit set to 800 kHz in 30 feet of water and scanning the exact same water and since I have a narrow 110 degree of coverage I can’t see the shoreline or the rocks near the shore. I can still see the stripe and the shad but in this case the 455 kHz gave me more detail than the 800 kHz setting.
Let’s wrap it up, the setting are really up to you and what depth water you are in. If you only have a Down Image unit the beams are different in that your choices are 455 kHz using a 75 degree cone angle and 800 kHz which only gives you a 45 degree cone angle which will not give you as much coverage as the side Image units. One recommendation I suggest is to set the Down Image to 800 kHz and the Side Image to 455 kHz while scanning so you don’t get the cross-talk if the transducer trying to pick them both up at once id you have them set to the same 455 or 800 kHz setting.
Hope this helps you better understand your unit better….
In this series of Side Image and Down Image scans I’m scanning an original creek channel in the back of Bear Creek on Pickwick Lake. While scanning I found an interesting object on the lake bottom.
This one will be of Objects Found.
Take a look at this side scan and see what you can find before looking at the photo below. As I showed you in the last Blog on Bottom Composition you can see the darker colors are a soft bottom in this case the original creek channel. And the brighter color is of the harder bottom composition. The shadows next to the objects lets you determine the height of the object on the lake bottom.
Photo 2 below…….
Now that you’ve had a chance to find the objects I’ll point out what you should have found. (1) is a false return as I was making a sharp turn with my boat so disregard it. (2) is a sunken tree top that either was placed there by another fisherman or washed into the creek and sank on its on. (3) is a very large stump that you can tell by the shadow it casts. (4) Finally as you can tell this is an old sunken boat. It looks to be a flat bottom boat without an outboard engine attached. The GPS coordinates of the area if you want to look at the objects to learn your unit is as follows.
GPS: N 34 48.113 – W088 05.365
Hope this helps you understand units.
In this series of Side Image and Down Image scans on my Blog I’m trying and teach you what you are looking at while scanning with your Side Image and Down Image. This one will be of bottom composition.
If you notice the dark color in the screen shot is a mud or muck bottom. The sonar signal is absorbed in the soft material where the hard bottom in this case gravel and rock is hard and the sonar signal returns very quickly thus a brighter color on your screen.
Hope this helps you understand units.
I started a series of Side Image and Down Image scans on my Blog to try and teach you what you should be looking for while scanning with your Side Image and Down Image. This one will be of a Flat in the back of a major creek. Hope this help your understand these expensive units.
Take a look at this photo before you scan down to the image below and see what you can find in this Side Image screen shot.
This screen shot side image was scanned in the fall of the year and as you can see there is a lot to be found in the image.
As you can see there is a lot to be seen in this photo look at the colored circles to see what is inside them.
Hope you find these photos useful.
I’m sure you’ve heard of the Mega Schools of Bass on Pickwick Lake. Here is a Down Image screen shot of just that.
In this screen shot from my Humminbird Onix I did a Down Image of a pier along a deep cove. In the photo you can clearly see the pier post, a couple of stumps and bass suspended under the pier and few bluegill hugging the bottom. When I scan using my Down Image I always use the 800 kHz settings to get a clearer detail image then I get with the 455 kHz setting.
I thought I’d start posting a few more photos from my Humminbird Onix Side Image units to show you what you should be seeing from the side scans. In this one I show you a small cut in the back of a larger creek arm that shows a a small creek channel leading out to the main creek arm.
How accurate is the Humminbird Onix Side Image units? Here is a photo of a recording I did with mine.
I had a chance to get out on Pickwick Lake yesterday and do a little fishing and side image recording with my Humminbird Onix 10 SI Cross Touch. While i was scanning in the back of Bear Creek I scanned these old railroad tracks. These tracks are part of the construction of the old canal system that starts t the mouth of First Creek on Wheeler Lake and runs all the way to Waterloo, Alabama. If you want to scan the tracks for yourself I posted the GPS coordinates on the photo.
You can see the train the used the tracks now located under Pickwick Lake.
U.S. Army Corps of Engineers Nashville District Historical Photo: This is a graveling crane and stone yard at Riverson, Ala., which is supporting the Colbert Shoals Canal project Nov. 8, 1895.
Here is a drawing of the canal lock that is submerged under Pickwick Lake that is across the river from Waterloo.
Construction of the Riverton canal, as you can see there was a lot of manual labor involved in the construction.
Setting the stones used in the construction of the lock. Most of the stones were cut from quarries up and down the Tennessee River. Keller quarry was one such place and you can still see some of the cut stones located there to this day.
Stones set in place as part of the Riverton canal.
Upriver entrance going into the entrance of the Riverton lock.
Down river gate exiting from the Riverton lock.
Humminbird Onix Side Image scan of the old Riverton Lock.
If you want to take a look at the lock with your Side and down Image units here is the GPS coordinates: N34.53.851 – W088.04.048 enjoy.
I like to record from my Side Image and Down Image units as I’m fishing. I usually try to spend the last 15 minutes or so of my day on the water recording what my units is scanning. If you don’t know how to do this there are a few older blogs on this site that will show you what you need and how to do it. Just do a search for RECORDING from the search bar on the right side of the screen.
As it was recording yesterday I found this old auto frame in Pickwick Lake. To me it looks like the frame might be the only thing left. Since it is upside down I can’t tell if it’s a truck or car frame. I’ll try to get a better image of it the next time I’m in the area. If you would like to take a look at it here are the GPS coordinates: N 34 46.333 – W087 42.199