This relationship between material density and the character of a radar return is important. Take for instance the radar’s response to a low-lying sand bar barely breaking the surface. At best, the target is displayed as a vague, often intermittent shape on the screen when the unit is set to short-range operation. At longer ranges, the partially awash sand bar remains invisible. Add a cluster of mangroves and a small marshy spit, and a more dominant image appears on the screen. Put a massive granite cliff in the background and it will eclipse whatever’s in the foreground. In fact, this is an important reason why care must be taken when using radar ranges to determine your distance from shore. In many instances the cliff or elevated rocky upland area is well inland, preceded by a long stretch of low-lying beach and surf-swept sandbars. The high-contrast representation of the cliff is by no means the water’s edge; rather it’s well inland from the hazards of the coastline, and the person using radar as a piloting tool should carefully take that into consideration. The best approach is to look at a chart (digital or paper) and compare it with the radar image or, if your radar is networked with the GPS/plotter and digital compass, you may be able to do a radar overlay. This is also a great way to confirm that the cartography and GPS signal are accurate, seldom an issue in the more trafficked waters of the western world, but a concern for those cruising well off the beaten path.