How might I go about measuring the tension in a line of fishing wire? I'm mostly interested in determining when the line is in tension vs when it's slack.
The application is a boat-mounted depth-finder. A weighted line could be lowered into the water via a stepper motor. When the weight hits the bottom, the line goes slack and the depth is determined by the stepper motor's rotations.
I'm considering the feasibility of this approach vs a sonar/fishfinder-type setup. A mechanical measurement would be kind of fun, in a way, despite its many flaws (accuracy, waterproofing..). Thanks!