GP1670F_1870F Operator's Manual - Furuno USA

7. FISH FINDER OPERATIONS7.4.2 How to select a zoom displayThe zoom displays appear on the left-half of the screen and the high or low frequencydisplay on the right half. Three zoom displays are available: bottom lock, bottom zoomand marker zoom.How to activate a zoom displayOpen the full RotoKey menu, select [Zoom] then [Btm Lock], [Btm Zoom] or [MkrZoom]. To deactivate the zoom display, select [Off] after selecting [Zoom].Bottom lock displayThe bottom lock display provides a compressed normal picture on the right half and a7 to 400 feet (3 to 120 meter) wide layer in contact with the bottom is expanded on theleft half. This display helps you distinguish the fish near the bottom from the bottomecho. You can select the bottom lock range with [BOTTOM LOCK RANGE] in the[RANGES] menu in the [FISH FINDER] menu.Bottom lock displaySingle freq. displayZoomedschool of fishSchool of fishZoom markerThis area zoomedand displayed onleft 1/2 of screen.Bottom shown as a straight lineBottom zoom displayThe bottom zoom display expands the bottom and the fish near the bottom accordingto the zoom range selected with [ZOOM RANGE] in the [RANGES] menu in the [FISHFINDER] menu. This display helps you find the density of the bottom. A bottom displayedwith a short echo tail normally indicates a soft bottom (sand bottom, etc.). Along echo tail indicates a hard bottom.Bottom zoom displaySingle freq. displayBottomZoom markerZoom markerautomaticallyfollows change indepth.7-4