Need some advise, The transom mounting instruction says, ”the transducer should be mounted at least 38 cm (15 in.) from the propeller”. Are they saying from the outer tip of the transducer to the prop or are the saying 15” horizontal across the transom? When I measure 15” across transom the trailer strap prevents me from mounting there on my Cobra. If horizontal is the answer, what ill effects will I get from only being 11-1/2” ?

Thanks in advance for any advise.