Furuno FR-7112 Using the Offset EBL, Tips for measuring bearing, Predicting collision course

6.0 NM
2.0	Target
	Cursor
	EBL1
	EBL2

5.Operate the trackball to pass EBL1 through the center of the target.

If the target tracks along the EBL towards the center of the display (your vessel’s position), the target may be on a collision course.

To cancel the offset EBL, press the [EBL OFF- SET] key.

Cursor

Bearing

EBL

EBL1 bearing 40.0° R

EBL1 bearing 135.0° R 40.0°R 4.0 NM

Figure 2-10 How to measure bearing by EBL

and cursor

Note: The bearing readout for the EBL and the cursor can be displayed in relative or true bearing (true bearing requires heading sensor input). For North-up and Course-up display modes the bearing reference is always true.

6.0 NM

2.0

EBL1 origin (initial position of target)

Target moved here.

EBL

EBL1 70.0° R bearing

Offset EBL (EBL1)

VRM

6.0NM VRM1 range

Tips for measuring bearing

ÁBearing measurements of smaller targets are more accurate; the center of larger target pips is not as easily identified.

ÁBearings of stationary or slower moving tar- gets are more accurate than bearings of faster moving targets.

ÁTo minimize bearing errors keep echoes in the outer half of the picture by changing the range scale; angular difference becomes dif- ficult to resolve as a target approaches the center of the display.

2.16 Using the Offset EBL

The offset EBL provides two functions: predict collision course of radar target and measure the range and the bearing between two targets.

Predicting collision course

1.Operate the trackball to place the cursor on the center of the target.

2.Press the [EBL 1] key to turn on EBL1.

3.Press the [EBL OFFSET] key. EBL1’s ori- gin shifts to cursor location.

4.After waiting several minutes, press the [EBL 1] key again.

Figure 2-11 Predicting collision course by

using the offset EBL

Measuring range and bearing between two targets

The procedure which follows shows how to measure the range and bearing between target “A” and target “B” in Figure 2-12.

1.Operate the trackball to place the cursor on the center of target “A”.

2.Press the [EBL 1] key to turn on EBL1.

3.Press the [EBL OFFSET] key. EBL1’s ori- gin shifts to cursor location.

4.Press the [EBL 1] key.

5.Operate the trackball to bisect target “B” with EBL1. Check the EBL1 readout to find the bearing between target “A” and target “B”.

6.Press the [VRM 1] key to turn on VRM1. Operate the trackball to place the outside edge of VRM1 on the inside edge of target “B”. Check the VRM readout to find the range between target “A” and target “B”.

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