one black ball:
two black balls:
“Not under command. Underway, but no way on. Adrift.”
Unable to follow any rules.
three black balls:
“Aground. Displayed aloft.”
two black balls, two diamonds:
“Vessel engaged in underwater work. Pass on diamond side; avoid ball side.”
Another beauty tip from Capt JJ: “You know how I remember it? girls love diamonds, so go for the diamonds. Or, you have to have balls to pass on the side with the balls. But the girls and diamonds one is easier, for me.”
ball diamond ball:
“Restricted in ability to maneuver. Working vessel.”
And, Capt JJ had to go there—“This is no good, either:”
— thanks, Capt JJ. I think.
If hungry for more, the COLREGS International Regulations for Preventing Collisions at Sea, published by the IMO, spells out in exhaustive detail the rules for lights, shapes (dayshapes like these), and sound signals.
Note: *No vessel ever has absolute ‘right of way’ over other vessels.* You can be the ‘give way’ (burdened) or the ‘stand on’ (privileged) vessel.