Choosing A Frequency - Furuno CH-300 Operator's Manual

1.7

Choosing a Frequency

You may choose low frequency or high frequency, with the LF/HF key. The display shows HI
or LO at the top of the screen depending on your selection. Use the table below to
determine which frequency to use.
Item
Long-range detection
Use in shallow waters
Detection range
(detection "leaks")
Detection of bottom
fish
Detection of bait fish
Affected by air
bubbles from other
vessels
The dual-frequency display is useful for comparing the picture from one frequency against
the other to overcome deficiencies in both. Use the single-frequency for objective-specific
fishing.
Low frequency
Low frequency
PREFERABLE
Attenuation loss is small on low
frequency.
NOT RECOMMENDED
Bottom echo is prominent
because of wide beam width so
fish echoes are hidden.
PREFERABLE
Detection area is wide (beam
width is wide).
NOT RECOMMENDED
Fish echo and bottom echo
overlap.
(Wide beam width)
NOT RECOMMENDED
Not suited for this purpose.
(Bait fish are not easily detected
with low frequency.)
NOT RECOMMENDED
Low frequency is easily interfered
by cavitation from other vessels.
High frequency
1. OPERATIONAL OVERVIEW
High frequency
NOT RECOMMENDED
Attenuation loss is great on high
frequency.
PREFERABLE
Bottom echo is less prominent
because of narrow beam width
so fish echoes are easy to find.
NOT RECOMMENDED
Detection area is narrow (beam
width is narrow).
PREFERABLE
Fish echo and bottom echo are
displayed separately.
(Narrow beam width)
PREFERABLE
Well suited for this purpose.
(Bait fish are more easily
detected with high frequency.)
PREFERABLE
High frequency is not easily
interfered by cavitation from other
vessels.
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