More Wissota Side Images

I had intended to run through a “to-do” list of requested Side Images on Friday, but the stiff wind and the fact that my 4.5 year old was with me limited the areas we could check out. With crappie poles in hand, we set out investigating some areas that were easily accessible and reasonably out of the wind. While I didn’t hit any of the places I really wanted to check out, we did find some interesting things worth sharing with the group.

This first image is one of my favorite early season shorelines. It is sheltered from strong north winds and has, what I had always perceived to be, a bunch of sunken timber along it (because of the number of jigs I have donated to this area). One pass with the Humminbird 997 confirmed my suspicions.

Here I’ve included the raw image (first frame) and then the same image annotated with a bit of interpretation. The second frame shows what I believe are downed logs, marked by red arrows, lying on the bottom. Note that they don’t cast a huge sonar shadow, so they aren’t extending off the bottom to any significant degree. The third frame has some brushpiles marked with squiggly yellow arrows. These brushpiles do extend off the bottom, as indicated by the fact that they do cast a sonar shadow (dark area behind thhe objects that the SI sonar doesn’t sample).

Here’s a different shoreline that had a bunch of fallen trees leaning into the water. The raw image is shown first, following by an interpreted version.

In the second frame, the big green arrows show off the tops of the fallen trees as they lie in the water. The thin branches block enough of the SI sonar to provide a significant, obvious shadow. The red arrow shows some logs lying flat on the bottom, and the yellow arrows show fish cruising along this shoreline. I don’t know what they are….we had trouble getting too many fish to open their mouths yesterday.

I wanted to show this next image for two reasons.

First, it shows the power of side imaging to detect differences in depth from a fair distance away (without having to drive directly over the depth change). On the left end of the side image you see a rocky point extending into the water (just to the right of 5:14). At the end of that point is a darker region, starting just above the point , wrapping around it and then extending below if for a little bit. This shoreline is along one of the rivers that feed Wissota, and this dark area is a washout hole produced by moving water wrapping around this point and scouring the bottom….much like you’d see off the tip of a wingdam on a larger river. The hole appears darker than the surrounding bottom because most of the SI sonar signal is reflected by the surrounding shallower water, which effectively shelters the deeper water from the sonar (making it appear darker).

The second reason I wanted to show this image was that it illustrates the effect of not changing screen speed relative to boat speed. For all of the images I shot yesterday, I was running a screen speed of 5, which provides nice images for me when I’m running between 3 and 4 mph (as you’ll see from the speed readings in the images above). Note that for this image, I was running under 2 mph (I was pulling cranks at the time). Moving too slow for the relatively fast screen speed has the effect of stretching everything out from top to bottom…which is why the features in this image look somewhat elongated. For an optimum image, I should have changed my screen speed to 3 (or maybe even 2) when running at this slower boat speed.

Finally, if you haven’t seen my “shipwreck” post, here’s another image showing that sunken boat. Be sure to check out that other thread for more info about the boat (shown by the red arrow) and the cribs to the right of it.

Humminbird Side Imaging reveals Wissota shipwreck

All I can say about side imaging is WOW. Thanks Jason great stuff

That really is cool stuff Jason! Thanks for taking the time to post!

VERY cool pictures, thanks Jason!

In your first image, there are 3 hard white spots (with shadows) on the SI right about in the middle of the screen. Would you think these might be fish (carp, walleyes, catfish, watever), or are they more likely logs or other structure… They look pretty good size, but they also look relatively fish-shaped and look to be just off bottom by the shadow… Any guess?

Thanks again

Mike

Mike, I think that those are dock poles. See how they’re in the shape of an “L”? I know there’s a dock just below that biggest brushpile, so I’m guessing those are poles from the dock, extending to the bottom.

The only thing that I don’t quite understand is why I don’t see a good shadow from the uppermost pole. Have to chew on that for a bit.

Ryan, these cribs are installed on an annual basis by the Chippewa Rod and Gun Club, under permit by the WI-DNR. They install between 20 and 30 each year. They are all built with a particular dimension, with particular materials, and sunk at a particular minimum depth so as to not interfere with boating or other recreational activities.

Jason, those are great SI pictures, it really helps my learning curve to see these, I am now getting pretty comfortable with my SI unit and loving it more every time out. I have the SD card now and hopefully will have some pictures to post soon.

Hi Jason! Nice side images. How about those GPS coordinates for the cribs I hear we may spend the day fishing together sooner than later. Until then… see you on the water!