To my knowledge during the Falklands conflict, there was a small Hull tug going down with the fleet and she lay on the outside alongside us and we transferred all her stores by our crane to her. She had a party of naval communicators on board fitting her out with the required radio. All naval transmissions and messages came as far as I was told just in a one second burst and in code which was probably automatically decoded. Our much esteemed member from Port William would know as he was there and one of such a team I believe. I also believe all the merchant ships carried such naval parties. Ref. your post Ivan as the aldis was generally known as the Daylight Signalling lamp and was directional, and was used day and night, I always wondered why so much emphasis was placed on the all round signal lamp, as every ship within range could see it. Was OK in the middle of nowhere when passing a ship but in shipping lanes would be distracting to other vessels. JS