Kelvin Hughes Direct Reading Current Meter (DRCM), with a sloping-fronted metal case, painted grey. Three dials: 'Knots'; 'Direction of Flow'; third uncalibrated, with red and green zones. Three rotary switches and two toggle switches. In a case with two booklets and a calibration chart stuck onto the lid.

The unit works in conjunction with NAV1762. A streamlined underwater unit with conical mesh tail (NAV1762) aligns itself so that it heads toward the stream. It contains a fluxgate system, which sends up the wire signals that are resolved in the indicator unit when a setting is made so that the angle between the direction of flow and the local magnetic meridian can be read of a circle. A four bladed propeller operates contacts, which send up the wire pulses whose frequency depends upon the water speed. A circuit in the indicator unit converts this pulse frequency into a voltage that shows on a meter, which is calibrated directly in water speed. So the DRCM shows on one dial the water speed and, after a setting operation, the direction of flow (magnetic) on another dial.