Want to hear something sad? I was digging around in the US sensor files.
There is an FM sonar and a broomstick in there. But how to get them working is beyond me at the moment.
edit:
I take tha back about the FM sonar, the models there, and i got a boat equiped with one. There is an UNUSED hydrophone node, slap it in, and i have an FM sonar head on my main deck.
The trick will be to get all these hydrophones to work in concert with one another.