NT888G MK2 AUTOPILOT OPERATING MANUAL
2.34 Setting Radius of Turn … (Continued).
NB.
The operational Radius of Turn (NM) is programmed within the Autopilot via the
LIMITS
Menu (Section 2.6 (vi)) but can be overruled by Track data command
received from a Type Approved Track Control System.
a) TO SET RADIUS OF TURN:-
Once Radius of Turn mode has been selected and set, any turns or heading changes
ordered will be limited by the Autopilot to the Radius (in Nautical Miles) set provided:-
Radius Mode selected (vs ROT) via Controls Menu (Sect. 2.4 (vi)).
Speed over the Ground (SOG) data available (Control Unit display).
The Control Unit display continuously shows the value of SET RADIUS OF TURN
thus the current operational value is always available.
REQUIRED OPERATIONAL RADIUS OF TURN:-
(i) Use the “
LIMITS
” key to enter the
Limits Menu.
(ii) Use the “
LIMITS
” key again to select
“
RAD:nm
” box followed by flashing
current value(
0.1 to 9.9
).
(iii) Use the rotary (+/-) illum. control to
set “
RAD:nm
” value required.
In the event that Speed over the Ground (SOG) data is absent or that SOG is to slow
to adequately control specified Radius of Turn geared to external forces etc. at that
speed, the Autopilot will generate alarms accordingly:-
No SOG data = “No radius control: Radius control unavailable, no SOG data”
display.
SOG too slow =
“Low speed: Ship’s speed is too low for HDG control”
display
accompanied by audible alarm.
2.35 Optimising the Off Heading & Course Comparator (CCA) Alarms.
The
Autopilot
OFF HEADING ALARM
(
OHA
) continuously monitors and compares
the difference between the heading set and the actual heading steered to generate an
audible and visual alarm if the specified limit is exceeded.
The OHA function differs greatly from the
COURSE COMPARATOR ALARM
function
(
CCA
) which does not compare actual heading with heading set but instead
compares the values of two Autopilot heading inputs to generate an audible and
visual alarm if one value (heading) differs by more than a programmed amount from
the other.
