Design a display unit for depth sounder with PIC16f877!!!

[bing2005]

I want to design my own depth sounder display unit by using Navman company depth transducer. Is it possible to do so?
So far i still try to find out the correct way to calculate the depth distance through this equation, Distance = Velocity x Time / 2.
Now, i am using Hi-Tech C to write the source code.
I want to figure out also how to measure the Time of the equation above.
If i can get the time value, then it should be no problem for me to find out the distance.
Thanks guys.

 

[prinsloo]

Time will depend on ground compesition,rocky will differ from sandy and marchy will differ from clay.
Search web for ground compesitions and speek to an rock/drill specialist.