Sailing Directions dating to 1884 note that Broad Haven is '? at its entrance is 1 1/2 cables wide?' and that the Stack or Church Rock is '... sufficiently remarkable to render the haven easily distinguishable by any vessel so distressed in a southwest gale, as to render beaching necessary. For this purpose Broad haven is to be preferred to any other spot between Milford and Tenby, and it is only necessary to give Stack rock a berth of a cable on the starboard hand; and the high tide floats here up, giving the better chance of saving vessel and cargo. These coves are occasionally available for the discharge of coal, ec, and when landing is practicable a good supply of water may be obtained at Broad haven.'

Sources include:
Admiralty; 1884, Sailing Directions for the Bristol Channel, 4th Ed, pg72

Maritime Officer, RCAHMW, September 2014.