The Adlard Coles Book of Radar

Radar is notoriously tricky to operate and 'read' correctly for
collision avoidance either with the land or with other vessels. But
used by an informed operator it is an immensely valuable navigation
tool - especially in poor visibility. GPS will tell you where you are,
but it won't tell you if there's another boat in that spot!

Rather than taking a theoretical, academic approach, this book is
highly practical and hands on - complementing the radar owner's manual
and explaining what the operator really needs to know when faced with actual situations at sea.

Packed with illustrative photos, charts and radar screen shots, this
book gives guidance from a real life, on-the-water perspective, and
will enable readers to solve problems on the spot.