Underwater speed?

[languer]

That is quite awesome. Could you have some sort of towed array to serve a GPS antenna? That way a GPS module can give you the speed, position, etc.

Another method I saw was to use two ultrasonic transducers; one on front and and one on back. The time for a pulse to reach the rear transducer through the water will be a fuction of the speed of the boat (think SONAR).

[Ioannis]

Very impressive! Like it a lot!

Ioannis

[Demon]

What about 2 pressure sensors front and back? The difference tells you velocity.

Robert

[Acetronics2]

Nice thing ...

@ 2000 Euros per piece ( 2500 US $ ) ...

Alain

[AvionicsMaster1]

Wow! Seems like such a simple question but I think it might require a complicated answer.

This site http://www.engineeringtoolbox.com/dy...re-d_1037.html can get you close but you've got to know density. This wiki site http://en.wikipedia.org/wiki/Density has a chart that shows water density at temperature.

So if you subsitute the fluid density p(rho) with the equation m/V your equation would be pd = 1/2 (m/V) v2. Solving for velocity would be, well I can't figure out how to write that here but you get the idea. What all this is trying to say is you'll have to get temperature somewhere.

I agree with all in that I'd like to see how you solve this problem.

[Demon]

(Talking out my wazoo on this)

But would density have a huge impact?

Is the sub going to be used in extreme temps, or only between ~15C - 20C?

Personally, I'd use it in temps and depths that I could dive to get it back (got no diving suit). But if you want to set a record crossing the English Channel, that's different.

Robert

[tasmod]

Hmm, your driving it with a propeller. Why not a small free rotating prop on conning tower and measure rotations.

There's example code on here somewhere for wind speed anenometer, which is basically same.

Rob