For anglers learning the basics of swinging flies for steelhead and salmon, the simplest way to think about presentation is to watch the head of the fly line during the swing and make adjustments.
We’re taught that, for example, you can speed up your fly by mending in a downstream belly – meaning that the head of the fly line bends towards the bank. Likewise, you can slow your fly by down mending upstream, creating a belly that generally straightens out as your fly starts to swing.
How the Fly Swims
Those principles are absolutely true, and definitely the right place to start – you can see the head of your fly line and learn how various mends impact how it moves. As you become more experienced swinging a fly, however, it becomes really important to think less about what your fly line is doing, and more about what your fly is doing. That’s what Walter’s going to eat, after all.
This can be a challenge when you’re fishing a sinktip, because you probably can’t see your fly. You need to put on you thinking cap, imagine what all those forces out there in the river are impacting your fly, and fish it actively!
In a lot of situations, your fly is doing basically what your line is doing, only much more so. The classic example comes in a run with fairly even current where you want to have a broadside presentation in a particular part of the swing where you think the fish are going to be. With a slight downstream belly in your fly line, your fly is very likely trailing your head and tip quite a bit more than you think – that thin leader just doesn’t have the mass to keep your fly ‘caught up’ with the heavier part of your rig. In addition to being further ‘behind’ your head, your fly is probably swinging more broadside than your head because of the ‘curl’ in your line.
In a run with more complex currents – say, a seam in the middle of your swing – your head is not going to swing uniformly. Mending can help straighten things out, but still, different parts of your rig can be moving in different directions in a complex current. In these situations, assuming that your fly is moving the same way as the majority of your head can be pretty misleading. For example, if you have a nice downstream belly through most of the head, but a current seam causes a tiny upstream belly right at the tip of your head, your fly might actually be moving really slowly, and not broadside at all.
Think About Your Fly
It’s not how your head swims that matters – it’s all about the fly. Don’t just watch the back end of your head and assume everything’s hunky-dory. Take that thought process all the way down the length of your head, through your tip and leader and right down to your fly!