For the purposes of section 293 of the Act, a prescribed measuring device is used in the prescribed manner if—
(a) whenever the operator connects the device to a source of electricity, the operator ensures that all elements of the speed display are illuminated; and
(b) the operator activates the device with the device aimed in the direction of a vessel within the operator's field of vision and observes the reading displayed on the digital speed display; and
(c) the device has been tested in accordance with regulation 89 within 12 months before the occasion of its use; and
(d) the device has not been unsealed since the seal was applied as described under regulation 90(b).