No, that in itself not a complicated idea. But playing out three miles of line with no tangles, anchoring it to a suitable point a fixed distance below the surface, applying tension to it without breaking it, and, let's not forget, finding and keeping track of the near-invisible fishing line a foot or more below the surface of the water, one and a half miles from the nearest point of reference?You know this is why I love you guys at MB. Around here its considered "complicated" to take standard 100lb test line which is nearly neutrally buoyant ,as it is, and place a length of it into a body of water while stretching it out
That doesn't sound simple to me. If it does to you, then by all means do it. I would love to see the results, and I mean that quite seriously. I am not trying to be needlessly negative, it's just that I can think of some much easier ways to demonstrate curvature.