At Nortek, we are often asked, "Can I use my DVL as an altimeter?" The answer is Yes, you can use a DVL to estimate distance over the bottom, but this is a qualified "Yes." DVL beams are slanted at an angle, so this measurement to the bottom needs to be corrected as if it were a direct vertical measurement. This becomes difficult to do if a vehicle is pitching and rolling.
To solve this, we included a dedicated vertical beam to act as an altimeter in our new Nucleus1000. This transducer takes a direct vertical measurement of distance to the bottom.