Furuno FR-1710, Operator'S Manual

Page: 29 / 78

1-15
0.55 NM
15.0
°
R
Bearing to
No. 1 EBL
Bearing to
No. 2 EBL
No. 1 EBL
(dotted)
EBL
45.5
°
R
314.0
°
R
Cursor Target
No. 2 EBL
(dashed)
Range and bearing
to cursor
Active marker is
circumscribed.
Figure 1-16 How to measure
bearing by EBL
1.20 Collision Assessment by
the Offset EBL
The origin of the EBL can be placed any-
where with the trackball to enable measure-
ment of range and bearing between any
targets. This function is also useful for as-
sessment of the potential risk of collision.
To assess possibility of collision:
1. Press the [EBL ON] key to display or ac-
tivate EBL No.1.
2. Place the cursor (+) on a target of inter-
est (A in the illustrated example) by oper-
ating the trackball.
3. Press the [EBL OFFSET] key, and the
origin of the active EBL shifts to the cur-
sor position. Press the [EBL OFFSET] key
again to anchor the EBL origin.
4. After waiting for a few minutes (at least 3
minutes), operate the EBL rotary control
until the EBL bisects the target at the new
position (A’). The EBL readout shows the
target ship’s course, which may be true
or relative depending on the settings on
the OTHER menu.
If relative motion is selected, it is also
possible to read CPA (Closest Point of
Approach) by using a VRM as shown in
Figure 1-17(a). If the EBL passes through
the sweep origin (own ship) as illustrated
Figure 1-17(b), the target ship is on a
collision course.
5. To return the EBL origin to the own ship
position, press the [EBL OFFSET] key
again.
(a) Evaluating target ship’s course and
CPA in relative motion mode
No.1
VRM
A
A
1
Cursor
VRM
3.85NM
EBL
140.0
°
R
No.1
EBL
(b) Target ship on collision course
No.1
EBL
VRM
0.00nm
EBL
118.2
°
R
A
A
1
Cursor
Figure 1-17 How to assess risk of collision
1.21 Measuring Range and
Bearing Between Two
Targets
1. Press the [EBL ON] key to activate the
No. 1 EBL. Press the [EBL OFFSET] key,
and place the origin of the No.1 EBL on a
target of interest (target 1 in Figure 1-18)
by operating the trackball.
2. Turn the EBL rotary control until the EBL
passes through another target of interest
(target 2 in Figure 1-18).