At W. H. Cooke & Co., we get phone calls in regards to thermocouple applications from engineers, purchasing agents, maintenance folks, and in this particular case, a fisherman named Frank. This gentleman is a fisherman in the Great Lakes region and he told me that he has found that the fish like to swim below the surface of the water in a specific temperature range.
He was looking for a way to detect the temperature of the water where his hook will be. We designed a thermocouple for him that he could attach to his line, just above the hook. We used a 1/2” x 1/2” stainless steel hex nipple fitting to act as a sinker with a small probe exiting the front of the bore of the nipple. Water resistant epoxy was used to seal the front of the nipple as well as the back of the nipple where the waterproof Teflon leads exited. Back on the boat, we sold Frank an Extech TM100 that he could use to read the thermocouple.
Now, he lets out enough line from his rod until he hits the depth where he knows the fish are biting and reels them in. Frank is a 21st century fisherman and while we don’t expect that everyone is ready to attach a thermocouple to their line and cast out, perhaps we can help you with a different unique application. You dream it, we’ll make it.