For most of you, it might be a case of just plug the sounder in and go.
Don’t get me wrong, the factory settings will get you out of trouble most days but to refine what you are looking at just might make that difference of spotting good fish and catching them rather than driving around in a continued search for them.
Today I am going to try my best to explain how the sonar works, adjusting the sensitivity and chart speed and why. I will be doing this on the Humminbird but you will pretty much have these options on any sounder that you have.
Firstly, you need to understand what you are reading on the screen, it doesn’t matter whether it is in the switchfire view, down imaging or side imaging.
Your transducer sends out sonar sound waves, when they hit an object it is reflected back as a shadow of this object as it can’t penetrate through. It is like a flashlight. If you point it at an object it creates a shadow on the wall, as the light can’t penetrate.
Your sensitivity is an adjustment of the dark and light colours. The idea is to adjust them to get a good contrast. A general rule would be if fishing hard bottoms such as rock etc; you would reduce the sensitivity to separate the brightness otherwise any showing of fish may just look like the same as the bottom – you need to get that contrast. In sandy bottoms, weed beds or in- between trees you might try a little higher sensitivity to show up the fish between the trees or weed beds etc; Generally speaking they will be shown as bright white lights when using the down imaging or side imaging. I will also change the sensitivity in varying water depths also. Just don’t get stuck in your ways, have a go and experiment; you will be amazed at what you might find. You can also freeze your screen by selecting the right arrow and then change the sensitivity. Sensitivity can be found in your sonar menu.
If you are changing the above you will also need to alter your chart speed. Basically the lower the setting the higher in detail but the further the object will be behind the boat. A simple explanation of this is if you had a camera and were walking past an object you could take a fair amount of photo’s before walking past, if you were running you may only get a couple of shots in. When idling past areas a good setting would be on 2-3 but when travelling or going faster than idling speed a higher setting is good for the initial search and then slow it down for more detail.
I hope these couple of tips help you refine your sounder skills and catch you more fish. As sounders are our eyes of the sea.