Strategy and limitations 2

When you are navigating near the coast or in a channel and the visibility is restricted, consult the echo sounder or depth recorder, Try to follow a depth contour on the chart that provides navigable waters and is clear of charted hazards.
Approaching a harbor in restricted visibility, use your echo sounder and make a note of the depth contours as you cross them.
That will provide you with a position line.
Additionally, locate a buoy on the chart and sail close to it, following the nearest depth contour.