Speed calibration

Speed transducer calibration is required as transducer performance is affected by a number of variables, such as transducer location, shape of the hull, and water flow characteristics. The purpose of performing Speed calibration is to ensure that the speed readings at the instrument are a true indication of the vessel’s actual speed.

CalibrationSpeedSpeed calibrationone pointSpeed calibrationSpeed Run

Prerequisites:

In order to achieve accurate results, speed calibration must be carried out in calm conditions with zero tide and zero current.

Speed calibration aligns the instrument’s log speed (Speed Through Water) to:

• Speed Over Ground (SOG), or

• A referenced speed

Calibrating using SOG

Speed calibrationFor most installations, a one point (quick) Speed Calibration will suffice.

If the one point calibration does not provide sufficiently accurate readings or you require a higher level of precision for your speed readings, a Speed Run Calibration can be carried out. It is advisable to carry out the Speed Run Calibration at as many different speeds as possible. This is particularly important for planing vessels.

⁽¹⁾Conventional speed transducers have a maximum of 5 calibration speeds, and smart transducers (e.g. DST800) have up to 8.

If required, each calibration point can also have a calibration factor applied to further align the log speed reading across different vessel speeds.

Calibrating without SOG

For most installations, a one point (quick) Speed Calibration will suffice. The calibration must be performed using a method of estimating actual vessel speed, and then adjusting the displayed reading so that the log speed matches your estimated speed.

If required, further calibration points can be added and a calibration factor can be applied to further align the log speed with actual vessel speed.

CalibrationSpeedSpeed calibrationone pointSpeed calibrationSpeed Run

	iTC-5		Smart (DST)		Speed pod
	SOG	No SOG	SOG	No SOG	SOG	No SOG
One point (quick) Speed Calibration
Speed Run Calibration
Manual Calibration