Need to fish deep - really deep? Or do you need something that cuts through a heavy current like a hot knife through butter..? What it all comes down to is the ratio of tungsten and plastic baked into your fly line coating. Mass and density are two metrics we use to define a fly line. Mass determines the weight of the fly line. This size is used to match the line and rod to obtain an ideal rod load.
Density, on the other hand, dictates whether a line floats or sinks, and it even determines how fast it sinks.
For fly lines, we measure mass in grains and grams (grains in the US and grams in Europe). We measure sink rate in IPS or Inches Per Second. As with mass, sink rate has tolerances to accommodate small changes due to different masses. A “sink 5” line sinks at 5 ± .5 IPS, while a “sink 8” line sinks even faster at 8 ± .5 IPS.
So what is the difference between the two UST 850 grain lines you see on the picture? Well, they both are designed by FFE and both have the same length, mass, and tapering, but that’s where the similarities end.
The UST 850 grain (left) is 55grams with a sink 5 density coating. The UST SHORT 850 grain (right) is 55grams with a sink 8 density coating. Both of these lines can be used on the same rod, but one will fish deeper than the other. See the difference?
The UST SHORT in 750 and 850 grains will sink faster than the same weights in the UST because the higher ratio of tungsten baked into them. That means that you have four badass options in the family of UST grain lines to tune the depth of your swing by.
That’s how serious we take the business of really fast sinking lines at FFE!