Implementation a vessel at anchor

A VESSEL AT ANCHOR:
A vessel of more than 50 meters in length, and at anchor shall exhibit where it can best be seen:
– In the fore part, an all-round white light
– At or near the stern, an all-round white light placed at a lower level than the forward light, and
– By day one black ball.
A vessel of less than 50 meters in length, at anchor shall exhibit:
– An all-round white light where it can best be seen, and
– By day one black ball.
A vessel at anchor may, and a vessel of 100 meters and more in length shall, also use the available working or equivalent lights to illuminate her decks.