About transducer draft

Transducer draft is the vertical distance between the water surface and the center of the transducer face. It may be desirable to account for the draft in your data in order for Echoview to correctly translate range to depth. See About depth, range and altitude for a diagram displaying draft and its relation to depth and range.

In Echoview, the draft is defined in terms of the location settings of transducer geometry. Specifically, the appropriate setting for draft is the Z - vertical offset setting on the Geometry page of the Transducer Properties dialog box. The distance entered into this setting is measured relative to the system reference point not the water surface and may, or may not, be the same as the actual draft (depending upon the position of the water surface in relation to the reference point - by default these are the coincident). See About transducer geometry for more details.

In Echoview 2, 'draft correction' was a calibration setting that accounted for the transducer draft in depth calculations. This setting has been replaced by transducer geometry. When an EV file created in Echoview 2 is opened in Echoview 3, the transducer geometry will automatically be adjusted for any draft correction settings. See Opening Version 2 EV files in Echoview 3 and higher for details.

Note for Simrad users:  If your echosounder is a Simrad Ex500 or Ex60, please read the page Logged draft warning. It has important information regarding your data.

See also

About depth, range and altitude
About transducer geometry
Transducer Properties dialog box