The 443 Velocity Profiler was designed to provide the precise speed-of-sound needed to calibrate survey depth sounders for variations in sound velocity in the water column for US Army Corps of Engineers customers and others involved with precision waterways maintenance or dredging surveys.

Before the advent of the 443, a “bar check” procedure was used whereby a bar or plate was lowered a known distance and suspended under the transducer face. Then, if the sounder chart reading was slightly different, the speed-of-sound adjustment on the sounder was changed until the chart read the correct distance. However, the bar check is not always easy or safe to perform. It is especially difficult on larger boats, in winter where icy conditions exist on deck and where currents make it difficult to position the bar correctly.

The criteria for developing the Model 443 was that the product provide data that was as good or better than provided by the manual bar check. Innerspace has accomplished this; the 443 is easier to use and provides better data more consistently than the manual bar check procedure. The customers using the 443 on their daily surveys find it to be an indispensable survey tool.

Since the 443 provides precise speed-of-sound for each foot of the water column, this data can also be used to correct acoustical transmissions from any underwater ranging device, such as transponders used in oil exploration and other applications.


The Model 443 Velocity Profiler acoustical measures and records an accurate speed-of-sound for each foot of the water column automatically as the probe is deployed. It then computes and displays sound speed and draft values for use in the depth sounder for calibration. The need to perform a bar check is eliminated. Since depth is determined by a sensor in the underwater probe, the length or angle of the cable paid out is unimportant, thus enabling the sampling of data while underway. Information from the 443 can be directly annotated on the chart of Innerspace sounders, thereby creating a truly archival document. Via the RS232 front panel connector, the speed-of-sound/depth values can be sent to a computer for further analysis of the water column speed-of-sound gradient.

The 443 also provides accurate speed-of-sound corrections for any near shore acoustic ranging application, including oil exploration surveys and scientific research, etc.

A number of US Army Corps of Engineers districts use the 443 as the main means of calibrating their depth sounders for their waterways maintenance surveys.

In our opinion, the 443 provides better information on a more consistent basis than does the manual bar check procedure. Ask our sales department for user references.


  • Eliminates cumbersome bar check procedures
  • Automatically calculates settings for speed of sound and draft correction in the depth sounder
  • Best fit readings for depths of interest
  • May be used as a stand alone velocity/depth meter
  • Automatic correction for barometric changes
  • Feet or meters modes
  • Fresh or salt water compensation
  • Serial data output available
  • One man operation
  • Can be used with any modern precision depth sounder
  • Annotate directly on chart of Innerspace sounders

Product data sheet is available; contact our sales department