1st it's important to understand that rotating the SI xducer 60° will not only "point" that SI piezo straight down ... It also "points" the opposite SI piezo toward the water's surface ...
This can cause some very un-natural and unsatisfactory images from that "upward-pointed" SI piezo reflecting off the water's surface ...
This issue can be eliminated by using the AS SIDB Y cable and removing the SI pin in the AS SIDB Y cable that connects the "upward-pointing" SI piezo ... (This is cheaper than removing a pin in a $270 HDSI xducer) ...
Using the AS SIDB Y cable is necessary anyway for the rotated SI xducer setup ...because the 2d piezo is no longer "pointing" down to get accurate depth readings ...
Another option for this Setup is a SI xducer that one side is not working anyway ...but the AS SIDB Y cable still needs to be used to get correct digital depth readings ...
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Now with one of the SI piezoes disconnected (or not working)... The SI image will only show data on one side (the side with the still live SI piezo) ...
The opposing side of the SI image will be black (because no data is able to get thru the AS SIDB Y cable SI pin that was removed) ...
Furthermore ... Because the DI image (in the HB SI unit) is a composite of the left and right SI data ... The processor now blends the "good" data from the live SI piezo with the "no data" from the dead SI piezo ... To get a DI image comprised only from data received in the SI piezo that is now "pointed" straight down ...
So it doesn't really matter which side the SI is set to view ... The SI image is no longer SI data (from the side) ...
The SI image is now "down-pointing" data ... Plotted into one side of the SI image ...
And the DI image is no longer "DI from side-pointing piezoes".. The DI image is now DI from a piezo that is pointed straight down ...
Rickie