Regulations for the Navy Part IICentral Regulations · 1957
(1) Should the absence of any of the documents mentioned in regulation 183 be likely to render it difficult for the officers mentioned therein to complete their task to the satisfaction of the court, it shall be permissible for the prosecution to call an expert witness (if possible a qualified Navigation Direction Officer) to assist the court.
(2) Such a witness shall not be called under regulation 183 and shall, with the permission of the court, be present to hear the evidence and shall then lay out the resulting courses on the chart.
(3) Such witness shall be subject to unrestricted cross-examination.