>I am also building a sub (a manned one, not model) so if anyone has some
>links to sonar, water speed/depth PIC projects or similar please let me know
>as well.

Fish finders work well upside-down.  The water surface is an excellent
reflector.  You get a good idea of depth that way, using sonar.  They also work
horizontally to detect obstacles.

The pressure sensor I used in the SubTech ADC will go below the 48" limit we set
in the model version.  You can also get other members of the same family with
more depth capability.

Those same pressure sensors will work for forward motion - but you need a really
sensitive one!

Andy

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