As I stated in a previous article discussing knots on the sighter section of a tight line nymphing leader…
There are many materials and methods for building a sighter into a tight line nymphing leader. A sighter, or section of hi-vis line in a leader, serves as a reference point for anglers to detect strikes. In addition to detecting strikes, it aids anglers with the ability to visualize where their flies are underwater, and how they are drifting. Since strike detection and drift awareness are two of the most important concepts in fly fishing, it makes sense to me that the sighter in a tight line nymphing leader is equally important.
Sighter diameter is yet another element of a tight line nymphing leader to consider. There are many different types of material that could be used to construct a sighter giving anglers many different options regarding diameter, or line size. For example, Rio 2-Tone Indicator Tippet is available is sizes ranging from 1x-4x. So what diameter, or size, should you choose? Well, that depends.
I think that the biggest deciding factor while choosing sighter diameter is dependent on the size of tippet you fish most often. If you frequently fished 3 or 4x tippet sizes then you would probably want a larger sighter diameter such as 1 or 2x. On the other hand if you frequently fish 5 or 6x tippet sizes you may want a smaller sighter diameter such as 3 or 4x. For example, I almost always fish Rio 2-Tone Indicator 3x Tippet as my sigher material. Most days on the water I fish with 5x tippet, but I truly want the option to be able to fish 4, 5, or 6x at any given moment. By using a 3x diameter sighter I am able to easily make minor adjustments to accommodate my preferred range of tippet sizes.
Another factor to consider when choosing sighter diameter is water conditions. On larger rivers with heavy riffles, the extra thickness from a larger diameter sighter will be a little easier to see. On smaller streams or in low, clear water a smaller diameter sighter will spook less fish. I know it might sound crazy that a sighter could spook a fish, but on some of the more technical trout streams I’ve watched it happen. I fish a variety of larger rivers and smaller streams, by choosing a 3x diameter sighter I feel as though I am well prepared to fish about anywhere.
Consider tippet size and water conditions while choosing a diameter for the sighter in a tight line nymphing leader. Basing your decision upon these two factors will help you construct a sighter that is based upon your own specific needs.