"Not under command" indicates catastrophic failure.
Failure of certain crucial steering/propulsion equipment that
does not warrant the use of that will call for "ball diamond
ball".
Ball diamond ball, Vessel restricted in her ability to manoeuvre
means a vessel which from the nature of her
work is restricted in her ability to manoeuvre as
required by the rule ...include but not limited to
1) Vessel engaged in laying servicing, or picking up a
navigational mark, submarine cable or pipeline.
2) Vessel engaged in dredging, surveying or underwater
operation
3) Vessel engaged in replenishment or tranferring persons,
provision, or cargo while underway.
4) Vessel engafed in lanching or recovery of aircraft
5) Vessel engaged in mine clearance operation
6)Vessel engaged in a towing operation such as serverely
restricts the towing vessel and her tow in their ability to deviate
from their course.
In the case of failure of steering or propulsion, vessels
will require the signal of Not Under Command
Vessel not under command which means a vessel which through
some exceptional
circumstances is unable to manoeurve as required by
the rules and is therefore unable to keep out of the way of another
vessel. 2 black ball and 2 all round red light.
More specifically you should also put up the signal of
Foxtrot flag for 'I am disabled. Communicate with me'.
or
Delta flag for 'Keep clear of me, i am manoeuvring with
difficulty'.
or for engine failure.
Romeo November flags for 'My engine is out of order'.
