Reading Railway Maps

It’s confession time.

Do we spend any time thinking about how we are going to fish the pool in front of us?

Or, do we just start at the top and make our way down pace by pace, trusting to Lady Luck?

And, do we always fish this pool the same way?

There are plenty more questions where those came from, but three are enough to make the point that we tend to apply more enthusiasm and energy than thought to the challenge of catching salmon.  I certainly did in my early years.  Yet even a short pause for thought leading to a simple plan can make a big difference.

Every pool is different and changes every day: water level, colour and temperature; air temperature and pressure; light, cloud and atmospheric conditions; and of course the location of the fish.  If we tried to bring all of those factors into our thinking we would rapidly descend into indecision because there’s too much to grasp and we don’t know what’s most important.  So we have to simplify.

First, what do we think the fish are doing?  Are they running, holding or settled?  If so, where?  (Have a look at last November’s post – 'Where are they').  Start by eliminating all the places they won’t be – those less than 30”/75cm deep; too insecure; too turbulent; too bright; or short of easy oxygen.  You’ve now reduced the problem by half.  Then work out the most likely running line that salmon will follow from one end of the pool to the other: the short halt lies will be on or very close to this line, and the holding areas not far away.  At the end of this process we have a mental railway map of the pool, comprising a main ‘running’ line from end to end; some ‘stations’ along it where fish congregate at the short halt; and some adjacent ‘sidings’ for slower-time holding areas.  Like all railways, the map is very narrow: 90% of all the hen fish I have ever caught took within a couple of metres of the running line.  (We’ll leave the more distributed resident fish snoozing on their ‘branch lines’ in peace for now).

Second, how deep is the water along the railway and how fast is the flow? (See the ‘Deep Thinking’ post).  The answers determine your initial choices of leader and fly size, but you should be ready to change both as you progress down the pool.

Third, where is the main flow and what is the current profile across the river?  Are there any obstacles or disruptions to the flow that will affect the movement of our line and the correct presentation of the fly? 

This example shows a common current pattern, with the strongest flow in the middle and a relatively quiet margin under the far bank.  A standard cross-cast (1) that reaches the assumed lie under the far bank causes the fly to land and anchor in slack water, whilst the line rapidly bows (2), which causes the fly to travel downstream (3) at high speed.  This will not sort itself out until the fly has reached the centreline, so half the cast was wasted.

The usual remedy is ‘mending’ the line – throwing a loop upstream with a ‘semi-cast’ to take out the bow.  Getting this right takes effort and practice.  If you are using a sink tip and weighted fly its efficacy is reduced because the far end is firmly stuck in the water.  In this case the cast (1) is followed by a mend (2) M2, which stops the problem getting worse, but you still waste the first third of the swing and all of the extra effort involved in getting to the far bank.  The simple message is don’t bother.  

Not only are there probably no fish there anyway, but mathematically you improve your chances by a massive 50% by working a more modest 60% of the water with your fly behaving properly.  An oblique cast to just beyond the centreline (1) produces a sustained line shape (2) that creates the ideal direction of fly travel (3).  Most importantly, the fly is effective immediately because you can take any slack in the leader with a small movement of the rod tip.

Of course there’s a place for square casting, especially in slower water, and mending the line is an essential skill.  But restraining your enthusiasm for hitting the far bank and opting for the oblique approach is a useful first step towards getting the fly in the right place.

Let’s now bring all this together in a practical example.  The picture is a ‘railway’ map of the Garden Pool at Tomatin for a water level of +12”/30cm.  The banks are green; the shallows grey; the main line red; the stations yellow (1-6); and the fast flow in blue (direction bottom right to top left).  These 6 are not the only lies in Garden, but they are the most heavily populated, and the more fish there are in a lie, the better your chance of a positive response.

At this water height and speed you want a larger fly (either a #6/8 double or a 1” tube) and a 5’ green or brown sink tip (it’s around 6’ deep at point 3).  Certainly you will need the brown tip to cut quickly down through the turbulent water at lies 1 &2, remembering that the more oblique your cast the slower the sink rate owing to the ‘lift’ of the water on the line.

To get the best fly presentation at lies 1 & 2 start well upstream and cast obliquely down at around 30 degrees to the flow.  This will keep the lateral speed under control; give the salmon more time; and increase the fly’s exposure to any fish actually running the main line.  If you are going to pull off a fluke it always pays to increase your chances.  (By now you should have spotted that this pool was the basis for the preceding current profile sketches.)

As you move downstream move progressively closer to the near bank (there’s no prizes for standing on a fish at 2); increase the casting angle to allow for the reducing flow speed; and continue to resist the temptation of the far bank.  Lies 3, 4 & 5 are typical mid-stream boulder features.  Although they are not visible in low water, at +12” and above they create a ‘standing wave’ (i.e. one that stays in much the same place in the current), as shown in the next diagram.

A wedge of static and slow moving water forms around the obstacle and forces the flow upwards, creating waves at the surface.  The shape of the wedge varies with the size, number and distribution of the rocks and the profile of the bottom.  Note that the deflecting effect of the current means that the standing wave is usually downstream of the lie.  Also that the wedge will form some distance upstream of the front edge of the obstacle. Your target therefore comprises the area upstream from the standing wave, possibly for as much as 12-15’/4-5m, depending on the depth and speed of the water.  The width of the standing wave in the stream will give you a clear indication of the lateral extent of the lie.  The salmon will be somewhere close to the bottom of the wedge that allows them to hold position with minimum effort – in front, between, beside or behind the rocks.  Remember that they are unlikely to venture far beyond its boundary to take, so you have to get the fly into the wedge, moving laterally at about 45 degrees above and ahead of the fish.

By the time you approach lie 5 you will need to change the leader and fly as the water is slower and shallower.  It is a large lie in length and breadth that only holds fish when the river us up 12" or more to provide adequate depth.  Lie 6, which also only comes into play at that level, is the exception that requires you to disobey, just for once, my ‘forget the far bank’ rule.  This is the heroic 35 yard pinpoint cast for which you have been saving your energy for the past hour.  Here the running line is close to the far bank.  Just short of the overhanging trees are two rocks set 4’ apart, where the fish stop for a breather after running the long shallow fast water from Colonel’s.  In your enthusiasm to get there, please don’t succumb to the temptation of standing on the fish in the back end of lie 5 that the next rod would like to catch.  But when you put the fly in the right place, at the right angle, moving the right way…………

On her way back
Garden Lie 6, 1430 pm, 12 September 2011

...then sometimes the magic happens.