12th February 2018

I have recently had a few conversations relating to my reasons for fishing light running leads and these have led to me writing this post in order to try to clarify my reasons. I say “try” because, technically, it is difficult, but I have tried to simplify it as much as I can. Here we go:-

FORCES UNDER WATER.

For many, many years now I have been using light leads on running rigs, otherwise known as ledger rigs. I have had considerable success with these and my totals, up to the point of writing this are 268 forties, 42 fifties and 3 sixties. That is not a boast but just to get the “numbers” out of the way as proof that it works. I also appreciate that I am fortunate to own my own lake so those captures are swollen by fishing my own water. However, I need to clear up, immediately, that they haven’t all come from my lake. Myself, and some of my friends, have had success with this system on estate lakes, gravel pits and rivers so it is not just working on one specific type of water. Now, with the results coming regularly, I had no real need to question why my tactics work until people began to question my reasons. It just doesn’t seem right to shrug and say “because it works” so I started to look into it and do some research.
Before I get into the detail let me jot down some of the queries that I received from anglers who needed some more clarification or proof.
The first and most obvious was “but you need a heavy lead to hook the fish.”
The second, because I fish slack lines was “you won’t see a bite until the fish has tightened the line.”
Those two “questions” were my starting point but my research also led to other benefits from the light lead approach so let’s get started.
I will try to illustrate each area of research as simply as possible but, to start with, there are two main forces acting in water which affect us while fishing. These are “Hydrodynamic slip” and “Hydrodynamic drag”.
We will take each one separately and try to illustrate how they affect us but, in fact, in our angling situation they actually work together as I’m sure you will realize throughout this brief detail.
The “slip” works along the length of an object in water and is generated by the shape of that object. i.e. long object generates more slip. It’s the force that keeps a ship traveling in a straight line and makes it difficult to stop quickly. It also works to keep our main line traveling in a straight line and Is simplest to imaging our line being in a “tube”. Now both forces work together to create this effect and I will come back to that at the end but I will just explain the “slip” allows the line to travel “lengthwise” and “drag” helps to prevent it moving sideways. The simplest way to illustrate this is to cast out a wagler float, allow the line to sink to the lake bed and leave the rod laying in the rod rest. Now, the float is the equivalent of your bobbin and the rod tip is the fish. Pick up the rod and see how far you can move the tip before the float moves. Almost immediately is the answer and long before the line is tight. In short, the line begins to “travel along its length” quicker than it moves sideways or upwards. That is why, with a slack line and a running rig, the bites are so obvious and come from just the bait being moved and not waiting until the lead is moved.
As I said above, the “drag” force stops the line from moving sideways easily and it is also this force which helps to hook the fish. Another easy example is to stand on the bank of a lake with a very thin cane and swish it backwards and forwards in the air. It’s very easy to do with very little effort. Now push the cane down into the water and try to swish it backwards and forwards. It’s much more difficult plus the cane sort of vibrates as it moves through the water and that is “drag”. This force acts on all surfaces of your line and that includes the top, so it makes it more difficult or heavier to lift up through the water. It is this force acting along the length of your line which actually hooks the fish so the weight is only necessary to reach the fish when casting. In fact it would be possible to calculate the weight effect of a certain length of line at a certain diameter but that gets far too complicated and beyond a mere angler like me.
Two more examples of how these forces work can be shown by underwater experiments carried out by other people. The first we all know about. A harpoon gun uses a simple piece of elastic to fire its missile underwater. The harpoon, being elongated like an arrow, benefits from the slip force traveling along its length and allows quite accurate shooting and will travel reasonable distances. On the other hand a bullet from a rifle, and there is a YouTube video of this exact experiment, does not work in the same way. I think we can all agree that, in general terms, a rifle is more powerful than a harpoon gun? The video, to which I refer above, shows a rifle set up on a tripod, beneath the surface of a swimming pool and the rifle is fully waterproofed. The man carrying out this experiment then climbs into the pool, in shorts, and stands about twenty feet in front of the rifle. When he pulls the cord to fire the rifle, the bullet doesn’t even reach him and it’s the drag force working against the short, blunt projectile that stops it short. In short again, the shape of the bullet isn’t long enough to benefit from the slip force.
Hopefully that has given you all some food for thought but I would just add a couple of things that also came about while doing this research. One was that I realized that I have been losing a lot less fish since switching to light leads and I am certain that this is mainly because they don’t have such a violent effect by bouncing up and down during the fight, as does a heavy lead, so the hook hold is less likely to get stretched and elongated and therefore less chance of the hook falling out. Another is that, for similar reasons, the lead is free to slide up and down so the fish is not tethered to the lead first and then the rod tip at a different angle. I also realized that a heavy lead can travel down through light weed and give you the feel that it has landed on a clearing when it is actually still weedy. If you feel the “donk” with a light lead, it is much more likely to be clear.
I would also add that fluoro main lines work more effectively, when being fished slack, than mono. I believe it is their inherent extra weight, and the fact that they don’t absorb water as mono does, that adds to the effectiveness of the two forces above.
Be lucky.