On the 2D's you are only seeing 1/3 the depth of the water you are in.
In 4 feet or less (it's less coverage than 1 feet any how), so what is the big deal (you are not going to see fish anyhow)?
If you want to see out (especally that shallow get a Humminbird SI unit).
Pretty much, anytime I'm less that 5 feet, I'm just looking to keep from running a ground with the 2D units.
That is all you should really expect on 2D.