Diving might not help much.....
I've tried that same recovery mission, for a slipmate who lost an aluminum bracket overboard. Put on my full scuba gear, took my largest dive lights, went down and could barely find the bottom, much less a small metal part.If the bottom is muddy and/or silty, the part will probably be covered in a few days, and it's likely that it fell at an angle, so it won't be right where you think it should be. On top of that, you're going to stir up the bottom just by going down there, which will further cut into visibility and cover the little bracket even more.Another problem is that the water is murky because of suspended particles, and a flashlight - no matter how powerful - is going to be of limited use.Sorry, I'm not trying to be gloomy, just realistic.On the other hand.... if you're looking for a reason to buy scuba gear and get into diving, go for it! In decent locations (I dunno about Tennessee), it is fabulous. ;DLooking at the bright side: at least you didn't drop BOTH brackets overboard, so at least you have a template in case you need to get one made.

Cheers,Bobs/v X SAIL R 8