i actually have a lure put out by Chuck Woolery that has the string type device you were talking abouth the frog having. It's a bass colored lure that swims for a few seconds after it hits the water and the string winds back in. It does swim. Maybe something with that type of coil spring system connected to a paddle wheel of sorts to make the lure back up? just a thought.

It's true hard work never killed anybody, but I figure, why take the chance?
Ronald Reagan
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The good Brian