You’ve spotted a certain buoy through the binoculars, but there are others not too far away. It’s critical that you have the right one, so how do you make sure? The easy answer is to steer so that the buoy comes into transit with an unambiguous headland, then note its compass bearing. Now read the bearing of the transit off the chart. If it doesn’t coincide with your observation, either the buoy is off-station or it’s the wrong one. Don’t expect split-degree accuracy here. Buoys are not fixed objects, but for these purposes, they’re usually close enough to call.