With gently tapered sink tips, like the 15' tips that come packaged with most Skagit heads, using average diameters and grain weights to calculate sink rate and rule number provides a good indication of how that tip will perform. For strongly tapered tips, however, there is considerable difference between how the butt and fly ends perform. We analyze this for some sample lines below.
Sink tips that strongly taper from butt to tip have the advantage that a cast turns the fly over more easily. Many anglers like them for that reason. But how do they perform underwater? To find out, we measured, weighed and tested the following lines.
Tapered Sink Tip ....................................................................Weight...... Rule Number
Spey VersiLeader 7 ips, 15', 24 lb (Rio) ................................ 178 grains................ 7.3
Spey VersiLeader 5.6 ips, 15', 24 lb (Rio).............................. 138 grains................ 9.1
PolyLeader, Salmon, "Extra Super Fast Sinking", 14' (Airflo)... 120 grains................ 9.1
PolyLeader, Salmon, "Fast Sinking", 14' (Airflo)...................... .54 grains................ 26
Among other things, we learned that the butts of these lines sink faster than their tips. See, for example, our measurements of the 7 ips (inches per second sink rate) VersiLeader in the table below. It turns out only the butt end sinks at 7 ips, whereas the tip end sinks more slowly (2.8 - 4.6 ips).
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| 7 ips VersiLeader -- Properties by Segment |
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We found that the PolyLeader "Extra Super Fast Sinking" is even more tapered than the 7 and 5.6 ips VersiLeaders. While its butt sinks at 6.8 ips, its tip sinks at 2.2 - 3.5 ips. Because all these lines are constructed with a constant-diameter monofilament core and a tapered tungsten-impregnated coating, the tip end simply has less of the heaving coating than the butt end. So the tip end sinks more slowly. We validated this conclusion by casting each line so that it landed horizontally on the surface of a swimming pool. In each case, it took the tip much longer to reach bottom than the butt, and more so for the PolyLeader than the VersiLeaders.
The fast-sink-butt-and-slow-sink-tip characteristic of these lines is undesirable from a fishing perspective -- particularly when you'd like your sink tip to pull an unweighted fly down to your desired fishing depth. In further swimming pool experiments with each line, we connected a floating line to the butt and a 3' 15 lb leader with a small (2.5") unweighted tube fly to the tip. Casting this setup so that it landed horizontally on the water, we noted that each of these lines sank with an undesirable "U" shape (the fly remained near the surface for too long). We wondered how much faster this fly would get down if the sinking line near the fly were made of the heavier butt-type material rather than the lighter tip-type material? To answer this, we reran these experiments with the sink tips reversed. That is, we attached the tip to the floating line, and the butt to the fly setup. While this made casting more difficult (though still doable), we learned that the reverse setup typically sank the fly more than 50% faster compared to the normal setup. Separately, we tried a weighted fly (with 1/30 oz lead eyes). This was easier to cast with a level sink tip than a tapered one and, in both cases, sank at about the same rate as the reverse set up.
In short, a taper is better for casting for an unweighted fly. But a reverse taper (or no taper) is better for sinking an unweighted fly and, in this case, for casting a weighted one.
Once the fly reaches it's desired fishing depth, the tapered sink tips perform similarly to non-tapered sink tips. The following graph (click here for BIGGER version) shows the shape and fly depth at hangdown for each tested line. It also shows the "equivalent" lengths of non-tapered sink tip (T-14 or LC-13) that would deliver a small unweighted fly to the same depth. Here are our key observations:
VersiLeader 7 ips 15' goes deepest. It is equivalent to using 13.5' of LC-13 or T-14.
VersiLeader 5.6 ips and PolyLeader "Extra Super Fast Sinking" are similar. Both are equivalent to using about 10' of LC-13 or T-14.
PolyLeader "Fast Sinking" is a slow-sinking, intermediate type line with butt-to-tip sink rates ranging from 2.8 to 1.0 ips. With an overall weight of just 54 grains, it doesn't weigh enough to sink faster or go deeper. Using it is like using an intermediate tip of the same length or 3' of LC-13 or T-14.
Overall, tapered tips make the most sense when fishing your fly at or near the surface -- when nice casting turnover of the fly is highly desirable and fly sink time is unimportant. In contrast, if you want your sink tip to help you to get your fly down quickly (or if you prefer to cast a weighted fly), level tips like LC-13 or T-14 are likely better.
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| Comparison of Tapered Sink Tips at Hangdown |
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