Furuno ARP-17 Acquiring Targets, Manual speed input, Target-based speed input, Manual acquisition

Manual speed input

Select MAN at step 2 above, press the [3] key twice, and enter speed with the ten keys.

Target-based speed input

This mode is used when the ship’s SDME (log) is not operating properly, ship’s speed is changed minutely (in case of no log), or the vessel has no device which detects ship’s leeward movement (doppler sonar 2-axis speed log, etc.) and leeward movement is not disregarded. You may select up to three targets, and they are marked as R1, R2, R3. They appear as tracked targets, each shown in a small circle, but without a vector. When a plural number of objects is selected, the mean value is used for stabilization and speed.

Note 1: The ATA calculates own ship’s speed relative to a fixed target. Therefore, when selecting a target, a larger ground mass or a long coast line is not suitable as a reference target because of obscure reference point.

Note 2: A vector can be displayed for the ref- erence target. This can be done with TAR- GET BASED SPEED on PLOT MENU 1.

Note 3: If a tracked target is acquired as a reference target it will become a lost target and cannot be reacquired. Therefore, when acquiring a reference target, select a target which is not being tracked. To select a tracked target as a reference target, cancel tracking and then acquire it as a reference target.

1.Select a small ground mass target (small island, lighthouse) 0.2 to 24 nautical miles from own ship.

2.Place the cursor on the target.

3.Press [MENU], [7], [7], [0], [0], [9], [9].

4.Place the cursor on the target and press the [PLOT SYMBOL] key ([ACQ] key on the FR-1710/1725/1760DS).

5.Press the [MENU] key.

The reference target mark (dashed square) appears at the cursor position and the own ship data label changes from LOG, NAV or MAN to REF. Note that it takes 60 scan be- fore a new speed is displayed, indicated by the target mark changing to a circle. If track- ing has failed for a reference target, the tar- get is marked with a lost target mark (symbol formed with two triangles).

6. Acquiring Targets

The ATA permits automatic acquisition (10 targets) plus manual acquisition (10 targets), or fully manual acquisition (20 targets) within a range of 0.2 to 32 miles. The targets are automatically numbered and the same num- bers are not used more than once until the maximum capacity is reached.

Before starting the ATA, check that heading and speed readouts at the top of the screen are correct.

Manual acquisition

1.Place the cursor (+) on a target of inter- est by operating the trackball.

2.Press the [PLOT SYMBOL] key ([ACQ] key on the FR-1710/1725/1760DS).

The plot symbol changes its shape accord- ing to the status as below, with plot number to the right of the plot symbol. A vector ap- pears in about 20 antenna scans after acqui- sition indicating the target’s motion trend. If the target is consistently detected for three minutes, the plot symbol changes to a solid mark. If acquisition fails, the target symbol blinks and disappears shortly.

6