Furuno 520 Operator's Manual page 31

Navigating to TLL point
When TLL (Target Latitude and Longitude) data is input from a radar or echo
sounder connected in the STBY, AUTO or NAV mode, the TURN menu appears.
Then, you may choose how to progress towards that position, from ORBIT (port
direction, starboard direction) or FIGURE EIGHT. (You may also continue current
steering mode, by choosing OFF.) Also, you can set the radius of orbit on this
menu. For this mode, own ship's position L/L data and waypoint L/L data are
required.
ORBIT
The boat makes circles around the TLL point.
SPIRAL
The boat goes to the TLL point spirally. After arriving to the TLL, the boat begins
orbiting around there.
FIGURE EIGHT
The boat automatically returns to the TLL position when it goes more than a
distance (set on menu) away from the TLL position.
Orbit around the TLL
Orbit maneuver
TLL
Orbit around the TLL
Spiral maneuver
TLL navigation
3. STEERING MODE
TLL
Distance set
on menu
Figure eight maneuver
TLL
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