Hi, I'm an electronic designer (and fisherman, of course) and I wasn't able to find the type of thermometer I wanted. Something that would be cheap (like me) digital, easy to read, and would have a long cable so I could reach down to 100'. I built a prototype for my own use that runs on a hearing aid battery, and connects to a weighted sensor that is heavy enough to sink to the bottom at most fresh water locations. The cable has depth marks at every 10 feet, so it's easy enough to take readings at any depth. Here's my question. I think I could put this on the market for about $20.00. Is that a fair price? If anyone knows of a product like this, let me know that I'm wasting my time. If you have questions, let me know that too, and I'll do my best to answer them. Geneeus