The Trolling Angles app provides the user with the ability to accurately determine the line length needed to troll any fishing lure at any desired depth.
This article provides a conceptual overview of the Trolling Angles app and how it’s data is used, without describing the details of the Trolling Angles screens and controls.
The Trolling Angles App is based on a patented method which can be summarized as:
Measuring line lengths and line angles at the surface, assuming those angles remain unchanged as the fishing line is deployed deeper, and computing depth curve data consisting of a sequence of one or more curves derived from the measured line lengths and angles.
The Calibration
The heart of Trolling Angles data is known as the Calibration. You use the app to measure and enter the data for a calibration. It consists of the original measurement of the several pairs of Line Lengths and their related Line Angles, and also the Rod Tip Height and Boat Speed that were in effect when the measurements were taken.
The calibration’s Line Length is always the total deployed line length from the terminal tackle to the rod tip. The app breaks this total length into the submerged line length and the unsubmerged line length while calculating and using the depth curve.
The Line Angle is the angle of the trolled fishing line in degrees with respect to horizontal. Trolling Angles v3 allows you to take multiple angle measurements for the same line length. They are averaged together to provide better accuracy and to allow you to identify and eliminate inaccurate outliers in your measurements.
The shape of a depth curve is highly dependent on the trolling Boat Speed, for rigs that are dominated by the weight of the lure and/or sinkers. For a neutrally buoyant diving rig, the depth curve is theoretically much less dependent on speed, but, especially for some lures with large lips, depth can be reduced somewhat as speed increases.
The Rod Tip Height is the distance between the rod tip and the water surface. The height and the line angle is important for calculating the unsubmerged line length. The Rod Tip height is assumed to be unchanged for each measurement of the calibration.
The Description
Trolling Angles allows you to enter and keep a set of attributes which describe the important description of a rig, including a calibration name, a lure name, line type, weight, and notes.
The calibration name must be unique. A numeric sequential calibration name is automatically assigned to a new calibration, but you are encouraged to change it to a name which allows you to find and identify the calibration.
The other attributes are recorded and displayed only to allow you to filter, find, and compare different calibrations. Even though these attributes definitely affect the real-world physics of a trolling line’s depth, their values are not actually used in any technical calculations by the Trolling Angles app, because the app measures the resultant combined real-world effect on the line rather than trying to use physics to calculate a predicted curve from their values.
If you use the same lure in several similar rigs that differ in weight, line, etc., or at different speeds, you should measure a separate calibration for each variant.
The Analyzed Depth Curve
In order to display a depth curve and to show the relationship between the line length and lure depth, the app uses the calibration data as input to perform a mathematical analysis and generate a detailed X,Y curve of the submerged portion of the line. This curve data is not stored persistently. It is regenerated from the calibration data whenever needed.
The app shows a graphics view of the side profile of the line. The app lets you adjust the desired depth and will show the required line length. The graph will show the lure position at 0,0, the water surface at any depth, and a curve along the submerged and unsubmerged line length.
The Trolling Conditions
When actually using a calibration, you may adjust the rod tip height to a different value than was used during measurement. Trolling Angles will adjust accordingly.
The App can use the smartphone’s GPS to show you your actual boat speed while trolling. This is so that you can control your boat speed to match the speed of the calibration, which is especially important for weighted rigs.
A “Speed Gauge”
The Trolling Angles app calls a set of related calibrations that differ only by speed a “Gauge”. All calibrations that have the same value in the Gauge attribute belong to the same gauge. Typically you will create a gauge for any heavy rig that you intend to troll in a range of different speeds. Create one calibration at the minimum reasonable trolling speed, another at the maximum reasonable trolling speed, and one or a few more at your most common intermediate trolling speeds.
A gauge is useful for two purposes.
Variable Speeds.
When trolling with a rig that is part of a gauge, you may enter any speed between the min and max. The app will interpolate the calibration data to generate a new artificial calibration curve for the speed you entered.
Water Current Gauge.
The action of the lure and the depth of the lure depends not on GPS speed of the boat and smartphone, but on the apparent speed of the lure and line with respect to the water. When fishing in a river or in a tidal current, this can make a very significant difference.
The Trolling Angles app can adjust the GPS reading of speed and direction over ground (SOG) by a known water current speed and direction, to provide the apparent speed and direction of the lure with respect to the water (STW).
With a Gauge of related calibrations for the same rig, Trolling Angles can use the GPS, the smartphone compass, and one more immediate measured angle of the trolled line to accurately determine the speed and direction of the water current at any time. This water current measurement can be used to show you the actual speed of the lure and line through the water.
