A fly line is typically broken up into 5 sections. 

  1. Tip
  2. Front Taper
  3. Body or belly
  4. Rear Taper
  5. Running line, Which I’ll define in this article.

The quick answer to WHAT IS RUNNING LINE IN FLY FISHING?  The running line is a thinly coated section of fly line between the rear taper and the backing connected to the reel.  It is typically between 35 and 55 feet in length and can be either floating or sinking.

What Does the Running Line Do?

The running line serves four primary purposes:

  1. Floatation or sinking properties dependent on the function of the fly line. 
  2. Very thin to reduce wind resistance and easy movement through the rod guides.
  3. Weight or mass to assist in the cast.  When fly fishing the fly line is the mass that casts the fly.  Unlike bait casting where the terminal tackle is what pulls the line out during a cast.
  4. Handling, particularly in the lower weight lines.  A running line is much easier to handle, mostof the time with lighter line weights fly line is retrieved by hand and not onthe reel.

Is Shooting Line and Running Line the Same?

Functionally shooting line and running line are the same thing.  Don’t get confused by the term Shooting Head which is completely different that a shooting line.

Shooting line is still the section of fly line between the rear taper and backing/reel.  Shooting line is commonly used in two handed/spey casting setups.    Usually a shooting line is separate section of  line that attaches to the rear taper and belly of the fly line.

Another common term used is Level Line which is interchangeable with the running line of a fly line.

To keep you in the “know”, folks usually use the term running line when the fly line is one continuous piece.  The term shooting line is used when the fly line is in separate sections.

How Do I Connect the Fly Line (Running Line Section) to the Backing / Fly Fishing Reel?

The most common way of attaching the running line section of the fly line to the reel is to tie a NAIL KNOT (see video below) to the backing.  Then the backing is attached tothe reel using an arbor knot.

Another way of attaching the shooting line is using a “Loop to Loop Connection.  Typically newer fly lines and shooting lines have welded loops.  These loops make attaching and changing lines and shooting heads easier. 

To avoid lot’s of confusion, I’ve written and reviewed what I think is the best fly line for trout in THIS ARTICLE FLY LINE FOR TROUT.

What kind of Knot Can You use for Shooting Line?

I connect shooting lines using loops.  Recently most shooting lines being used are either a braided nylon or coated solid monofilament. The knot that I’ve found works the best is the double surgeons loop.  I tie the loop and really tighten it down to the point of almost melting the line.

Can I Cut the Running Line Section of my Fly Line?

Yes, in fact on many fly reels designed to balance with fly rods in the 0 to 3 line weight the reel will not have enough capacity to handle the full length of the fly line.  In those cases, I’ve clipped off 30 feet of running line in order to have a little backing and properly fill the reel.

Are There Different Kinds of Fly Fishing Shooting/Running Lines?

I?m going to list 4 of the most popular types of running/shooting lines.

  1. I’m calling this traditional, this is the coated braided core line you see on 90% of the fly lines sold.  The core is either a solid mono or braided.  The braided lines are a little more supple, were the mono has less stretch.
  2. Coated monofilament, this is becoming real popular with the spey casting community for Skagit line setups.  Very thin, stiff, casts well and tends to sink.
  3. Coated Gel Spun Poly (GSP), much like the mono above.  It has the advantage of being pound for pound thinner and has no stretch. This is a little more difficult to tie knots into.  If you can afford it, this is what I recommend.
  4. Hollow Braided, this is a lot like the backing used on a fly reel.  It is a little thicker than all of the above types.  It isn’t used as much anymore, Hollow Braid tends to pick up water, but it does have good knot properties and very little stretch.

To summarize if or occasionally change your line using a “line kit” switching from floating to sinking line, gowith the traditional.  If you have a spey rod setup for Skagit fishing.  Get the coated GSP. 

Chart of Types and Characteristics of Running Line

I thought it might be handy to outline the types and characteristics of running lines.

Why is Understanding your Fly Line So Complicated?

The technical jargon makes this seem complicated, the reality this isn?t tough. This post provided the essential definitions in the first couple paragraphs.   Fundamentally, the running line extends the float(or sink) characteristics of the fly line. With most modern fly lines pushing the belly of the line forward, those simple line purposes described above: float/sink, thinness, low mass and friendly handling are the things to look for.

One of the cool spots I’ve found for reading about fly lines is on the Sceintific Anglers website. Here’s a link to SA.