Understanding Fly Lines Part II:
Sinking Lines
(As appeared in "The Technical Fly Fisherman", June 2004 issue of Northwoods Sporting Journal)
By Bob Mallard

 

Although advancements pertaining to floating fly lines seem to get all the attention these days we have made some major improvements in regard to sinking and sinking-tip fly lines as well. Today we have sinking and sinking-tip fly lines in a much wider range of sink-rates than ever before (from 1.5" to 9" per second). In addition, we now have sinking-tip lines with a wide variety of tip lengths (from 5' to over 25'). Lastly, we now have hybrid sinking-tip lines that combine different types of sinking lines (usually an intermediate/sinking) as opposed to the traditional floating/sinking design.

Add to this how the tapers are designed and how the lines in fact sink, and today's fly fisherman has more options regarding sinking and sinking-tip lines than ever before! However, as with many of today's technical advances, how many anglers actually know what makes one sinking or sinking-tip line different from the next and in fact, which one is best for them? Unlike floating line, the tackle that we use should have little impact on the sinking lines we buy. Specifically, it is the conditions we can expect to encounter that should influence what sinking lines we buy.

The most significant improvement in recent years regarding sinking and sinking-tip lines is what is referred to as "Density Compensated" or "Uniform Sink". These terms refer to a sinking line that sinks tip first as opposed to belly first like the older lines. Scientific Anglers accomplishes this by putting powdered tungsten or high-density glass beads in the coating of their sinking lines. By putting more tungsten or glass in the tip, the tip sinks faster than the rest of the line thus eliminating the traditional sagging where the belly of the line often sinks much faster than the tip of the line and subsequently the fly.

Next is diameter. Today's sinking lines are much thinner than those made in the past. This not only aids in sinking (thin line sinks faster than thick line), but it also helps in regard to casting by reducing friction. In addition, thinner line takes up less room on a reel and as such can have some bearing on tackle selection and line rigging. For example, the stated capacity for most if not all reels is based on a typical 90' weight-forward (WF) floating fly line and a specific amount of backing (usually 20# braided Dacron for freshwater and 30# braided Dacron for saltwater).

However, while the typical 5'-15' sinking-tip line takes up the same amount of space as most WF floating lines, the typical sinking line can take up a whole lot less space. As such, you should downsize your reel size if sinking line is all you are going to use. Specifically, if you plan on using a 6-weight sinking line only, consider buying a reel rated for a 5-weight (based on 100 yards of 20# backing). If however you are using the reel for both floating and sinking lines, you will need 25-50% more backing than the reel is rated for (125-150 yards of backing will be required to fill a spool rated for 100 yards of backing).

All sinking and sinking-tip fly lines employ some sort of a weight-forward taper (they rarely if ever come in DT or Level tapers). However, while most sinking lines use a traditional WF design with a short to medium length front taper, many modern sinking-tip lines come in specialty multi-step WF tapers that are designed to eliminate the "hinging" effect found in many older sinking-tip lines. Additionally, certain high-end sinking lines such as Scientific Anglers Mastery Uniform Sink Plus use a taper similar to that found in sinking-tip lines to enhance performance (it helps the tip sink first buy reducing bulk).

Of far greater importance to the angler is the sink-rate. In fact, it is the sink-rate more than anything else that will determine how a sinking or sinking-tip fly line will perform. While simple on the face, many old myths about sink-rates are no longer valid (and maybe never were). My favorite statement is "I've got to get down deep and I've got to get down fast". In some cases this is completely inaccurate (you don't need to go deep at all), in others it is half-inaccurate (you need to go deep but don't need to get there fast). Here is what every angler needs to know about sink-rates:

Type of Line
Sink-Rate
Effective Fishing Depth
Line Weights Available
Intermediate 1.25" - 2.00" 2' - 4' 2-10
Type I (1) 1.50" - 2.25" 2' - 4' 5-8
Type II (2)
 1.75" - 3.00" 2' - 6' 4-8
Type III (3) 2.50" - 4.00" 3' - 10' 4-10
Type IV (4) 4.00" - 5.00" 4' - 20' 4-10
Type V (5) 4.50" - 6.00" 8' - 15' 7-10
Type VI (6) 6.00" - 7.00" 10' - 20' 4-9
RIO Deep 7 7.00" - 9.00" 15' - 30' 5-8 (7 Optimal)
RIO Hypersink 8.00" - 9.00" 15' - 40' 9-11

 

Notes:
 - Sink-Rates are listed in "Inches Per Second" (IPS).

- Effective Fishing Depth denotes where in the water column you wish to fish as opposed to how deep the water is (and there is a difference!).

- While there is no industry standard regarding sink-rates, they are fairly similar across manufacturers. For the exact sink-rate, refer to the manufacturer specs on the outside of the fly line box.

- Most lines listed above are freshwater lines. Saltwater sinking lines are denoted by "Grain Weight" and reflect a rod weight (300 grain = 8/9-weight) more than a sink-rate (300 grain sinks roughly 7" per second). Choosing a saltwater sinking line based on a sink-rate can have negative results (it might not load your rod properly).


As far as what sink-rate is best, my theory in regard to sinking lines is the opposite of my theory in regard to sinking-tip lines. While I prefer slower sink-rates (Intermediate to Type III) for sinking lines (when used in lakes and ponds), I prefer fast sink-rates (Type IV - VI) for sinking-tip lines. Specifically, a slower sink-rate allows you to fish both shallow and deep by using a "count-down" method. This is the best way to fish sinking lines on lakes and ponds. Conversely, the water in rivers is moving and unless the line sinks fast it often misses its target (it never gets down to the fish).

Equally as important in regard to sinking-tip lines is the length of the tip (this is the part that sinks). This will have a huge effect on how far a line will actually sink (regardless of the sink-rate). Specifically, a 10' sinking-tip can only sink so far (even if it is a Type V). As such, vendors offer a broad range of tip lengths to satisfy a large variety of conditions. So, when it comes to sinking-tip fly lines, both sink-rate and tip length is equally as important. Here is what every angler needs to know about sinking-tip tip lengths:

Monthly Tackle Tip: While floating fly lines should be cleaned periodically, treated when necessary 9and only when recommended by the manufacturer), and replaced every couple of years, the life span of a sinking line is much longer. However, sinking-tip lines will start to crack as quickly as floating lines and in some cases quicker (we often use them harder!).

Bob Mallard has been a flyfisherman and fly tyer for over 25 years and is the owner of Kennebec River Outfitters on Route 201 in Madison, ME. He can be reached at (207) 474-2500 or www.kennebecriveroutfitters.com.