Fly line explained

Unlike ordinary fishing line, fly line is thick and heavy — that is the point: the weight of the line loads the rod and carries out the weightless fly. For put and take you only need to understand two things: the profile (usually WF) and how it behaves in the water (floats, sinks slowly or sinks).

WF and depth

WF means Weight Forward: the weight sits in the front of the line, which makes it easy to cast and the standard for beginners. The line is given a class and must match rod and fly reel, for example class 5. Wrong class makes the rod feel dead or overloaded.

• Floating sits on the surface. Easiest to cast and control, good for near-surface fishing and beginners.
• Intermediate sinks very slowly and holds the fly just under the surface.
• Sink-tip and sinking take the fly down, either only the front or the whole line.

For rainbow you want at least a floating line and an intermediate or sink-tip, so you can meet the fish wherever it stands. Many solve that with spare spools. A Booby on a sinking line just above the bottom is a classic trick when fish stay down — see streamer fishing. Wipe the line now and then; a clean line shoots better. More: lines and leaders.