BlueWater Boats & Sportsfishing – April 01, 2018

Clutter control up until the blue noise disappears. The
sounder is now tuned to the current depth, but will
need to be continually adjusted as your depth changes.

• Time Varied Gain (TVG) is signal compensation that
  removes transmission loss effects from echo sounder
  data. Set the TVG distance to match the depth. You
  normally set up a preset for TVG on your Function key.


• Turn Pulse Edge on if getting echoes from another
  nearby sounder.


• Use split-screen and Zoom to target defined depth
  ranges, and then tune as above to suit each mode.

Nick Hamilton-Smith – Simrad
Nick is one of the experts at Navico, the parent company
for leading sounder brands Lowrance and Simrad.
Nick’s tips for deep-water fishfinding include:

• Use low frequency for depths over 150m.


• Ensure your transducer can get to your required
  depth range, using a minimum of 1kW with a narrow
  beam for depths 200m and greater.


• Set your sounder to Manual Range to zoom in on
  the bottom.


• Reduce surface clutter to allow greater sensitivity
  at depth.


• Slow the ping speed down.


• Once focused on the bottom, increase sensitivity
  and colour.


• Slow the unit’s scroll speed.

Grant Watson – Raymarine
Grant is a manager at Raymarine and is responsible
for handling sales and service. He offers the following
advice:

• In deeper water, a narrow beam angle will provide
  a more focused beam, hence providing clearer
  resolution of both fish and bottom structure. However,
  it is pointless having a narrow-beam transducer if your
  unit doesn’t have the power to provide a return of
  the bottom or identify targets. That’s why it’s always
  important to use the higher frequency when trying to
  distinguish close-together targets such as schools of
  bottom fish or bait species.


• Take care to select the best transducer to suit your
  boat as well as your budget.


• Be careful with transducer location and mounting.
  You must minimise aeration under the vessel and over
  the transducer’s face, which will show on your screen
  as gaps in the bottom.
  
  
  • A 23cm display screen with a quality transducer
    will give you better results than a 30cm screen with
    a cheaper transducer. It is a good idea to invest in a
    good transducer initially, as you can always network a
    second screen later when the funds become available.
    It’s much less likely that you’ll later remove a cheaper
    transducer and upgrade.
  
  
  • Use Manual range setting.
  
  
  • Use Zoom to magnify the bottom image. Every
    screen has a limited number of pixels, but units like
    the Raymarine Axiom Pro and CP range offer ‘True
    Zoom’, providing extra detail in the zoomed area.
  
  
  • Once you locate fish, use your chartplotter to
    understand how quickly and what direction you are
    moving. I often use my Anchor Drag Alarm set to
    400m to inform me when I have drifted off the mark.
  
  
  • I like to increase my Auto Gain until there are
    returns showing in the water column as this informs
    me that I have the maximum usable Gain for the
    current conditions.
  
  
  • Understand electrical noise. You will see more noise
    the deeper you go, since the amount of power in the
    sonar signal is being spread thinner as it tries to see
    a lot further.
    If you start to get vertical lines on the screen when
    someone plugs their mobile phone in to charge, or
    when you turn the livebait tank pump on, get the
    boat’s wiring looked over. These vertical lines can also
    come from interference caused by the sounders of
    other nearby boats.
  
  
  • Once you have the right electronics, believe in
    them. Don’t worry that everyone else is fishing 500
    metres away; they are probably only following the
    person that was there before them.
  
  
  
  

AN EXPERT’S CHOICE

As an example of what to look for in a sounder for

deep-water work, Mark Reid’s list below explains

the features of the Furuno FCV1150 and FCV295

models that he particularly loves for searching deep

canyons and drop-offs. He highlights these as the

most important attributes that will help you to find the

bottom structure and activity that attract swordfish.

Mark says:

• These two units offer dual frequency from 28 to 200
  kHz, along with the ability to run 1kW on high frequency
  and 2 or 3kW on low frequency independently. Both
  sounders also have dual Gain control for low and high

“Instead of

sending just

one frequency

from the

transducer,

CHIRP sends

a continuous

sweep of

frequencies,

ranging from

low to high.”

Above left:

Swordfish have now

become a regular

catch for gamefishing

boats of all sizes, as

long as they are set

up with a sounder

capable of finding the

necessary bottom

structure in depths of

400 to 800m.

Above: The pomfret

is one of the mid-

water oceanic species

occasionally caught

while targeting

swordfish over deep-

water canyons and

drop-offs.

bluewatermag.com.au 45

Sounding Out The Final Frontier