Whistle
Historically the boatswain's call was used to pass commands to the crew when the voice could not be heard over the sounds of the sea. Because of its high pitch, it could be heard over the activities of the crew and bad weather.
"Still" is used to call all hands to attention as a mark of respect, to order silence, to give an instruction. It is always followed, after an interval, by "Carry On".
On a ship the occasions which the “Still” is, or might be, used.
Can be used in the vicinity of work to avert an accident.
At Colours and Evening Colours before the Ensign is hoisted and lowered
As a mark of respect on the arrival or departure of a visitor who it is wished to honour but is not entitled to be piped over the side.
When it is necessary to give detailed Orders which requires absolute quiet.
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