I have an 898c HD SI and have mounted two transducers. The original si transducer and a hs transducer utilizing the required splitter wire. Do I have to manually choose which transducer to use each time I want to use si or hs or do they operate at the same time? Additionally, in the instructions it says to go to "sonar" and choose a transducer. Many are listed but there is no designated "hs" only dual beam, quad beam, etc. Which one is the correct one for the XNT 9 20? Thanks