Furuno FAR-2107(-BB) - Manual (Page 189)

4. AIS OPERATION
4-15
4. Set items 2-5 as appropriate, referring the description below.
MAX RANGE: Any AIS lost targets beyond this range will not trigger
the lost target alarm.
MIN SHIP SPEED: Any AIS lost targets slower than this setting will not
trigger the lost target alarm.
EXCEPT CLASS B: Select ON to prevent trigger lost B class AIS lost
target.
MIN SHIP LENGTH: Any AIS lost targets whose length is shorter than this
setting will not trigger the lost target alarm.
5. Push the right button several times to close the menu.
4.10.2 Enabling, disabling the lost target alarm
The LOST TARGET ALARM box at the bottom right corner enables and disables
the lost target alarm. Select OFF, ALL or FILT as appropriate.
OFF: Disable the alarm.
ALL: Get the alarm against all lost targets.
FILT: Get the alarm against the AIS targets whose criteria meet
the settings on the AIS LOST FILTER menu.
CPA AUTO ACTIVATE OFF
CPA AUTO ACTIVATE box