Furuno GP-1600F manual Zoom displays, Bottom-lock

Zoom displays

Three types of the zoom displays are available: bottom-lock, bot- tom zoom, and marker zoom.

Bottom-lock

The bottom-lock expansion display provides a compressed normal display on the right side and a "narrow" or "wide" layer (distance depends on unit of measurement) in contact with the seabed onto the rest of the screen with the seabed contour displayed by a straight line on the bottom-lock display. This display offers excellent bot- tom fish discrimination, which is vital for bottom trawling.

Bottom-lock display

	50				0
			68.3		50
	40
					100
	30
	20
						150
162	10			200k	200
	0
CSE 180.0°		SPD	16.8kt			2D
DEP 113.6 ft		TMP 16.0 °C			12.0V
POS 34° 26.245' N			135° 41.232' E

Display range marker

Normal display

Figure 3-4 Bottom-lock display

Note: For the bottom-lock expansion display, the seabed contour must be steadily and distinctly plotted. Adjust the gain or select automatic operation. You may select the bottom-lock expansion range (wide or narrow) on the SOUNDER SETUP menu in the SYSTEM menu.

Bottom zoom

The bottom zoom display expands bottom and bottom fish echoes two, three, four or five times on the left half of the screen. The zone expanded is indicated by the zoom range markers on the nor- mal display.

The zone automatically moves so that the bottom echoes locate on the lower half screen.

This mode is useful for observing hardness of the bottom closely together with bottom fish. Many fishermen find the place where bottom fish are likely to be, from the shape of bottom profile and length of bottom echoes. The length of the bottom echo is an indi-

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