Kobberbassen imitates a crustacean, a gammarus/seaweed flea that lives in the vegetation in close to the shore. This fly is fished with both short- and longer distinct retreives, from only 10cm to almost half meter. If there is calm weather and little wind you can use long, thin leaders for such fishing. Up to two rod lengths and down to 4X/0,18mm tippet. This is a good strategy, especially if the fish is up and rising. If you are able to see the direction of the fish, present the fly carefully a bit away from the rise. If you cannot see the direction, it's wise to wait for the next rise before you present your fly, rather than running the risk of spooking the fish. Delicate presentations and patience is half the job in these conditions, also pay attention while the fly sinks and keep focus on the tip of the line. Trout sometimes take the fly in this phase too.
The crustaceans are also exposed as prey when the waves strike sharply against land. Then the stream will sometimes force various crustaceans out of the hiding places. The sea trout know this and patrol quite close to land under such conditions.