I've lost a couple rods in the past as well, mainly when kayaking (beginner and didn't tether like I do now).

Your best bet would have been to mark the spot with GPS and come back in the summer to swim down and feel (or as/hire your son or grandson to do it lol). Good luck with your rod, but I very seriously doubt you'll be able to pick it up on DI or SI (but I could be wrong). I have a 999 (console) & 899 (bow) and love these units. Once I learned how to use them it was game on!

-Scuba