When entering a poorly marked narrow channel either in daylight or especially at night it is very tempting to aim straight up the middle.
The disadvantage of this approach is that if the bottom shelves unexpectedly it is not immediately obvious which way to turn to find deep water.
One approach is to deliberately aim to follow one side of the channel, perhaps by following a depth contour. In this case, if the depth reduces, you should know on which side to find deeper water.
Another approach is to zig zag up the channel. That is aim at an angle across, then when a suitable depth is reached near the edge to turn and angle across to meet the other side.
Both of these techniques remove the uncertainty of where the deep water is to be found.
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