Setting Cpa/Tcpa Alarm Ranges - Furuno FR-2105 Operator's Manual

Set and drift corrections are beneficial for increasing the accuracy of vectors and target data.
The correction is best made in the head-up mode with true vectors, watching landmasses, or
other stationary targets. Thus, the speed and course of own ship over the ground are
reciprocally calculated and compared with the relative bearing and range to the reference
target to produce a Set and Drift. These values are automatically applied to all targets. If
stationary targets have vectors, set and drift values should be adjusted until they lose vectors.
Proceed as follows to enter set and drift (rate):
1. Press the RADAR MENU key to show the FUNCTIONS 1 menu.
2. Press the [0] key to show the FUNCTIONS 2 menu.
3. Press the [7] key to select menu item SET, DRIFT.
4. Further press the [7] key to select OFF or MAN option.
OFF: No correction against set and drift.
MAN: Manual entry of set and drift data.
5. If OFF is selected, press the ENTER key.
6. If you have selected MAN in step 4 above, the highlight cursor will advance to right
requesting you to enter SET xxx.x°. Enter the value of set in degrees by hitting numeric
keys without omitting leading zeroes, if any, and press the ENTER key.
The highlight cursor will then advance to the next line DRIFT xx.xKT. Enter the value of
drift in knots by hitting numeric keys without omitting leading zeroes, if any, and press the
ENTER key. Set and drift have the same effect on own ship and all targets.
7. Press the RADAR MENU key to close the menu. The label LOG (or NAV) on the top of
the display changes to SMG xx.x KTBT, where SMG stands for Speed Made Good and BT,
Bottom Track. Set and drift data can also be used in the basic radar without ARPA
function.

2.13 Setting CPA/TCPA Alarm Ranges

The ARPA continuously monitors the predicted range at the Closest Point of Approach (CPA)
and predicted time to CPA (TCPA) of each tracked target to own ship.
When the predicted CPA of any target becomes smaller than a preset CPA alarm range and its
predicted TCPA less than a preset TCPA alarm limit, the ARPA releases an aural alarm and
displays the warning label COLLISION on the screen. In addition, the ARPA symbol changes
to a triangle and flashes together with its vector.
Provided that this feature is used correctly, it will help prevent the risk of collision by alerting
you to threatening targets. It is important that GAIN, A/C SEA, A/C RAIN and other radar
controls are properly adjusted.
CPA/TCPA alarm ranges must be set up properly taking into consideration the size, tonnage,
speed, turning performance and other characteristics of own ship.
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