This answer depends greatly on the size of the vessel at anchor.
Rules of the Road. RULE 35,SOUND SIGNALS IN RESTRICTED VISIBILITY
(g/f) A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds. In a vessel 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely one short, one long and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.
An anchor ball is a sphere attached to the vessel of an anchor buoy, used as a signal to state that the vessel is anchored.
When boating at night, a single white light on a vessel tells you that it is anchored.
No, a vessel anchored cannot be a "vessel not under command".. International / Inland Navigational Rules of the Road General definitions Rule-3 For the purpose of these rules, except where the context otherwise requires: (f) The term "vessel not under command" means a vessel through some exceptional circumstance is unable to maneuver as required by these rules and is therefore unable to keep out of the way of another vessel. This may apply to a vessel underway, NOT making way. Please refer to the link below.
All round white light
A ship is assigned a "berth" or a "boatslip" (or just plain "slip").
Keeping his/her vessel and crew out of danger
loud
~200 feet.
its easy sound signal
The Blue Peter is flown
This answer depends greatly on the size of the vessel at anchor. Rules of the Road. RULE 35,SOUND SIGNALS IN RESTRICTED VISIBILITY (g/f) A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds. In a vessel 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely one short, one long and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.
You are approaching the stern of another vessel and may be overtaking it