Goingbig; SI does not work as a shoot thru hull (in hull)install.
You may try a thru hull with a HB XTH 9 DB 35 KW T or a XPTH 9 HDSI 180 T, big hole in the bottom being a thru hull.
If the boat hull is single layer (not multilayer) a in hull may work but may have diminished returns in 2d. SI will not work!!!!
Hope this helps a little. Roddy