The reason it appears to be in the water column is because the only thing a transducer knows is how far an object is from the transducer .... and since the water depth is greater than the distance the object was from the transducer, the system will show the object to be the depth in the water column = to it's distance from the transducer.
It's easy to get tricked into believing our units are so good now you know exactly where things are ..... but there are limitations as shown, and that must always be kept in mind when viewing things with imaging.
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Looking for the one that makes it all worthwhile.