Hans wrote: > Hi John, > > Yes, sinking lines have a higher desity, but the first 30' still have > to weigh in at the same weight as a floater to fall within the same > aftma rating. To achieve this, the profile will be much thinner. With > this thinner profile the line will cut through the air differently > during the cast, will move faster, but as Gallileo proved ages ago, > does not fall onto the water any faster. > > Cheers, > Hans > Don't think that's quite what Gallileo proved. While I agree that the difference in frontal area between a floater and sinker isn't likely to affect the speed at impact much, it does affect it; otherwise skydivers would have mighty messy landings!
Now to the more complicated subject of weight, profile, and tapers. The fact that the AFTMA rating is only for the first 30' of line is important, as is the fact that there is a rather liberal tolerance. If one looks at the tech specs for the Cortland 555, one can see that the numbers as given are impossible. Take the 5-weight DT and WF for example. The WF has the same tip and body diameters as the DT, but the tip is 6" longer and the front taper is 2' longer. Making the reasonable assumption that the core is the same size and density in both lines, they both cannot weight 150 grains for the first 30' unless the coating is of a different density (also very unlikely). This is likely an artifact of truncating small numbers. For example, if the body diameter of the DT line is .0472" and of the WF line is .0478" (given as .047" in the Cortland table), all would work out. Or it is the result of Cortland using the "nominal" AFTMA weight, not the actual weight. Many folks misunderstand the nature of flylines and their names. The Weight-Forward designation is misleading when considering short casts. As Hans rightly pointed out, there is no significant difference between a DT and WF for 45' casts (30' line, 15' leader). WF lines were developed for longer casts; they are an attempt to duplicate the shooting-head set-ups of competition casters without the hassles of mono running lines. Relatively speaking, a fly rod has a rather limited range of aerialized distributed weights that it can handle regardless of how brilliantly one tries to distribute this by tapering. The WF line has a much greater portion of its TOTAL weight "forward" because of the weight and diameter of the "shooting" or "running" line is greatly reduced. What I find interesting is that Cortland increases both the tip and front taper length on its WF design vs the DT design. Hans can probably shed more light on this than I, but it seems to me this can only be to enhance turnover on long casts. If it was an advantage in short casting it should be duplicated in the DT version. Cheers, Paul -- Paul Marriner Outdoor Writing & Photography. Member OWAA & OWC. Author of Atlantic Salmon, Ausable River Journal, Miramichi River Journal, and Modern Atlantic Salmon Flies.
