Control of the Rod Angle R and the importance of the length of the rod

For a given fishing distance, the Rod angle angle will be determined by the angle formed between the rod and the water surface. The main effect of this angle is the length of tippet under the water. The more horizontal the angle, the longer the section of tippet under the water and therefore the greater drag and lift.

Keeping this angle as vertical as possible, will shorten length of the underwater tippet and minimize drag. Ideally this angle should be 90º with a vertical leader, but these angles are only feasible when fishing short distances.

Some situations permit fishing short, such as when heavy water prevents the fish from being spooked. But in most situations this angle will be lower than 90º because some fishing distance is usually needed. Different rod angles will result in different lift forces, and that’s something that needs to be kept under control. Learning how this angle affects lift and drag is important in mastering the advanced techniques. Sometimes it’s better to use low rod angles when faced with certain situations. For instance, using shallower rod angles when fishing shallow water will keep the flies from touching bottom without having to change the rig. Drag, and therefore lift, both depend on the current speed, and sometimes you’ll need to compensate for insufficient lift by using a reduced R angle to increase lift and keep your flies at the desired depth.

Tippet length under the water for different R angles

To quantify the influence of this angle on the drag force, I had access to some hydrodynamic and geometric calculations. You can check them in this Blog.The conclusions are very interesting. The best angle to minimize drag is R 90º, and when going from a vertical angle (close to 90º) to a horizontal angle (close to 0º), the drag force increases as shown in next figure.

Drag forces with different R angles compare with drag force with R 90º

On the X axis in the graph you can see R angles, and on the Y axis you can see the drag force increment versus the drag force for R=90º. From R=90º to 75º, the drag increase is not very substantial, just 6%. When R angle is 50º, the drag force is 31% bigger, though. And it’s very important to notice that beyond 45º the drag increases a lot with any new R angle decrease, having at 20º a 192% bigger drag force than at 90º.

Influence of Rod Length

It is well known how longer rods provide more reach. A rod one foot longer will provide the angler with approximately two feet more reach. But long rods also allow you to fish with more vertical R angles, which results in a better drift. This is really the main advantage of using long rods in contact nymphing, since with regular-length rods reach is not a limitation when using a long leader in place of a fly line.