Submersible Sonar Suggestions

Greetings,

I am part of a small University engineering team that is building a submersible capable of capturing video footage of fishing nets in hatcheries and possible damage to dams. While we believe we're on track for the most part, we are having trouble locating a suitable sonar unit for collision detection and for detecting the distance to lakebed. I've found numerous tutorials for using sonar for rangefinding and collision detection for dry environments, but nothing so far for submersibles.

Any help in finding a suitable Sonar unit would be greatly appreciated.

Thanks

hm, for what ranges/areas and for what resolution do you intend to find such a unit?

perhaps steal the transponder from a depth finder, like a 'humminbird'.

As far as collision detection, just a few feet, but for depth to the bottom of the lakebed, whatever we could afford. We are trying to stay under $200, but as it stands any recommendations would be great.

I'm also looking at depth finding .... and just spotted the Humminbird RF45 Advance Remote Sonar Sensor on Amazon.com for $25 and wondered how 'hackable' it was.

As an alternative, there are lots of NMEA 0183 tranducers available in the $80-$100 range. They have a serial interface and output a CVS text string. If you have a West Marine nearby you can get one there for approx $100.

--Tim.