Actual sink rate question

[Rattus]

When using (fairly heavily) weighted flies on sinking line, is the actual sink rate of the fly somewhat faster than the rated sink rate of the line?

In other words, does the weighted fly, which would sink on its own faster than the sinking line, “pull” the sinking line down faster than its rated sink rate?

[Tailingloop]

Good Question. I have a simple answer for you. You (and anyone else reading this) can wade through the following and skip to the end.

Fly line sink rates are generally measured but putting 1 to 2 inches segments in a tub of freshwater in a lab and using a suite of instruments to measure the rate. See http://www.flyfishingresearch.net/sinkrate.html

Different portions of a sinking line may sink at different rates. Originally this was due to changes of diameter along the taper with lines of constant density, often resulting in a belly forming such the the tip was higher in the water column than fatter parts of the taper. In the 1990s lines started appearing where the thin tip section was a bit more dense so it would sink faster than the fatter belly section. Today we even have triple density fly lines that have three sink rates lists ( or a floating and two sinking).

The rate at which a fly sinks depends on its weight and construction. I have some pretty heavy flies that are bulky but don't sink as fast as some lighter flies because of bulky or buoyant materials.

It is possibly that a bulky or buoyant fly can impede the tip section from sinking as fast as it would without a fly and leader attached. You can design a fly that will sink faster than the sinking portion of the fly line, which will help.

And so we get to the answer:

Yes, if a fly has enough density and mass to sink faster than the fly line, in can pull the fly line down faster than the specified sink rate of the flyline. This is more likely to happen if the fly starts sinking with the slack in the leader and can pick up some speed before the leader comes tight to the fly line. It is also more likely to happen if the fly line has some slack in the end. It is less likely to happen if you make a nice long cast that lays out perfectly. When fishing for calico bass around the kelp or other structure I often use weighted flies made with non-buoyant materials that will sink quickly and make intentionally sloppy casts. I watch the line as it sinks like a hawk. If the line suddenly speeds up, twitches, jumps or halts while sinking I will strip in the slack and set the hook.