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Discussion Starter · #1 ·
Question for the Barners-I inherited a Furuno FCV-667 Depth Sounder and used it all last year offshore and in. I seem to be picking up structure but I am concerned I am not marking fish. Now this could be because A-I am not on fish, B the transducer is bad. Howveer, I have caught fish and never noticed anything on the screen. I know some guys even see their anchor lines which I don't/ We have had multiple shark hook ups anchored with nothing on the sounder. So my question is should I get new equipment? Maybe just the transducer? Why am I not hearing or seeing the fish marks? Any info would be appreciated thanks guys. Counting down the days!
 

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What wattage ducer?
In hull/wet box/out?

Are you proficient with tuning the sounder in terms of gain?
Are you running it on auto-gain?

If you can see a thermocline, you can see fish.
 

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could be the transducer. Make sure it matches with the unit. that information can be found in the owners manual. After that, a lot of it is about how you set it up. I rarely rely on Auto, and change my gain etc as conditions call for.
 

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I have a 662 and leave it on auto with fish symbols all the time as I don't feel proficient in the many adjustments that The Foruno is capable of. I not only see everything that passes under the boat but the sizes we catch are usualy the sizes the machine is designating to the fish.
 

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Discussion Starter · #5 ·
I usually run it on auto but have adjusted the gain when it gets out of control and there are red dots all over the screen/ I can see the thermocline (assuming you mean the bottom?). Maybe just need to get a new transducer or clean it up.I am not sure of the wattage. It is in hull.
 

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I usually run it on auto but have adjusted the gain when it gets out of control and there are red dots all over the screen/ I can see the thermocline (assuming you mean the bottom?). Maybe just need to get a new transducer or clean it up.I am not sure of the wattage. It is in hull.
DC, the thermocline is the space in the water, where temperature and salinity change to the extent it creates an echo and is not the bottom. more typically, offshore fishermen use the thermoclines as indicators to locate areas holding bait. I dont fish inshore very often so I can't speak to what you may see 30 fathoms and shallower. When running on manual mode, it's a good thing to turn the gain up to the point you have clutter, then back it off such that there is no clutter, but perhaps a heavy surface signal, but clear bottom signal. I'm certain if you go onto youtube, someone has likely posted a manual tuning of a depth finder
 

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I had an FCV-667 on my last boat for 15 years. It's a 600 watt unit. There are no such things as fish symbols on that model. I would see fish, the anchor line, thermoclines and very detailed bottom structure. I would run it on AUTO when cruising and it would hold bottom and read out really well. You would even see large shools of fish and bait while cruising.

When I was bottom fishing, the unit when into MANual mode. I would turn down the interference rejection and turn up the gain until the screen was all red, then back off a bit. You still want to see some speckles on the screen. To see bottom and fish detail really good, I would keep the max amount of gain, with the minimum amount of filtering. You can also use the zoom function when bottom fishing so you just display the bottom 20ft. A lot more detail was visible when I used zoom. I would see clouds of sea bass in blue, hovering over the rock bottom that was displayed in red. I learned a lot about bottom fishing and using fishfinders back in the 80's fishing with Capt. Greg Venturo. He was a diver and really good bottom fisherman. One thing he always said, was that you had to read through the interference, to see the fish. If you back the gain down until the screen is clear, except for the bottom, you are missing a lot.
 
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