I was hoping someone here would have an answer, their phone support is iffy. I called 3 times to find out if I could use 2 SI transducers because I don't have a clear shot to both sides, got 2 yes answers and 1 no then 2 different cables were offered with one being completely wrong. Like I said the specs say no but an antenna is listed as an accessory and the antenna says it will work with the 698. No straight answers it seems.