For those of you who seem to be overthinking this, in most cases the swingback from a feeder is relatively small in all but the most extreme cases.

Take the following scenario, showing a cross section of a simplified swim:

Let us assume, that the angler casts from a point C on the bank and casts a feeder 60m out to the lake surface on a tight line, the feeder hits the surface at point L and swings down on a tight line to rest on the bottom at point R in 3m of water - 60m diagonally from point C. Directly above point R is point E, the effective distance that the feeder is effectively fishing. The question then becomes, how far is point E (the effective fishing point) from the landing point, L, since this is the distance that the feeder has swung back from it's landing point, and potentially the distance between a falling cloud of bait and the rig.

Well fortunately, in our idealised solution we have a simple right angled triangle formed by the points C, E and R.

We know the length CR (60m), and ER (3m), so by using a bit of Pythagoras' hypothesis (I refuse to call it a theorem since he was unable to prove it) we can work out that CE is 59.92m. Given that the cast was originally 60m, we can therefore work out that the feeder has swung back by a massive 0.08m or 8cm. Which is practical terms is nothing - if you allow for some variability in casting accuracy, line stretch, wind, line arcing, and/or bounce the difference is negligible.

However there are scenarios where this could be a major factor - particularly in short cast, deep water scenarios. Be way of illustration, please find below a table showing the swing back distances (in metres and percentages) for a range of distances and depths:

I've included the extreme case of fishing at 10m distance in 10m of water to show the extreme case (and test the formula), since in this case on a swimming pool profiled lake you would expect the feeder to end up under your feet. In general terms though, unless the water is very deep (say a quarter or more of the distance you are casting) you probably have nothing to worry about.

#spanky #mathsisfun #idontknowwhatahashtagis