A:
I have the same Fish finder i used those plastic straps to mount it to the top securely. The top of the mount doesnt have holes and the thing is made of steel and would take forever to drill holes in it. So a simple solution is to just use those straps once secured you can turn the fishfinder the other way and once mounted the fishfinder is adjustable ,you can turn it to your position.
Fits perfectly on my Porta/Bote