Good question jbrady2852 and one that I see getting answered incorrectly sometimes:
Yes, you can use the AS-Si-DB-Y cable to connect an inside-the-hull DI transducer to a transom mounted Di transducer.
However, I would question why you want to do this. If this is to get better depth readings at higher boat speeds than this will work but you will need to change the Digital depth Source menu to the “2D Element” setting. The reason for this is, unlike most of our units, the DI model units use the DI sonar to determine the water depth. When using the AS-Si-DB-Y cable most connect the “Dual Beam” connector to the inside-the-hull transducer. Doing so without making this menu change will not change how the unit will determine the water depth, so you have to make the menu change to tell the unit to use the 2D sonar (from the inside-the-hull transducer) to determine the water depth.