[CA11] Stern drive AXIOM RV transducer installation

[SeaBat]

Hello folks,

I wish to upgrade a Raymarine C-70 MFD with a thru hull 50/200 kHz transducer to an AXIOM 9 RV for a 2006 27’ Sea Ray Amberjack 270 equipped with a single I/O engine and a transom dead rise of 21 degrees. I am very anxious regarding the selection of the appropriate transducer and its location. There appears to be no perfect solution for a RV transducer for this stern drive application. As the bottom of the keel is rounded (please refer to the first of the three attached pics) this apparently rules out the use of a single RV-200 thru hull transducer which requires a flat surface. Also, I’m hesitant to attempt to replace the existing thru hull transducer since, while it is believed to be an Air Mar, there is no tag attached so that the exact model is unknown, and without that the exact diameter is unknown. I thought that the installation of a pair of RV-2xx thru hull transducers between the keel and the first chine (please refer to the first of the three attached pics) would be a good choice, but my mechanic said that he would not do that, because that is where a bunk trailer pad would most likely lie. Although I don’t own a trailer the mechanic uses one to transport the boat. I also considered the installation of a pair of RV-2xx thru hull transducers located forward of the water intakes that are located on each side of the keel (please refer to the first of the three attached pics), but there appears to be insufficient room to do so in the bilge, as the fuel tank is located forward of the water intakes (please refer to the second of the three attached pics).
The local Raymarine rep recommended the installation of a RV100 which could be connected via a Y cable with the existing 50/200 kHz thru hull transducer. With such an installation it is realized that the performance of the side scan on the side of the outdrive opposite to that of the RV100 will not be optimal.
For such an installation, where on the transome would be the best place to locate a RV-100? Please refer to the third of the three attached pics. The blue tape on both sides of the transom indicates where the water intakes, which can be seen in the second pic, are located. The speed/temp sensor on the starboard side can be removed, if necessary, as it is attached to the current C-70, which is to be replaced with the AXIOM 9. The sensor on the port side is for a Fish Hawk down speed/temp/depth unit.

Thanks in advance for any suggestions,
SeaBat