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Old 09 August 2012, 16:17   #1
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Depth finder problem with...

...shallow depths. It's my day for having electrical gremlings today. Now this has been happening on and off for a little while, but a close shave with a shallow bank earlier today has prompted me to get to the bottom of this.

When using the depth finder in anything deeper than 35 feet it works fine. Go shallower than this and it stops reading the bottom and displaying depth. The transducer is sikaflexed in the hull and I've used ever manual and auto setting on the unit.

Is there anywhere else I could start looking?
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Old 09 August 2012, 16:43   #2
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I would check the cable for kinks or pinches.
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Old 09 August 2012, 17:07   #3
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I wasn't sure of the model before, but I am now, it's a Raymarine A65 and DSM25 depth finder module which shows no faults.
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Old 09 August 2012, 17:10   #4
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I would check the cable for kinks or pinches.
I'm very confident that this isn't the problem as I'm very particular on cable runs etc. That said however there is a large coil of excessive cable in the console (perhaps about 15'), perhaps I'll unravel it and might pull a bit more into the hull before my next trip out.
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Old 09 August 2012, 18:09   #5
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Quote:
Originally Posted by Hightower
...shallow depths. It's my day for having electrical gremlings today. Now this has been happening on and off for a little while, but a close shave with a shallow bank earlier today has prompted me to get to the bottom of this.

When using the depth finder in anything deeper than 35 feet it works fine. Go shallower than this and it stops reading the bottom and displaying depth. The transducer is sikaflexed in the hull and I've used ever manual and auto setting on the unit.

Is there anywhere else I could start looking?
I'm having the same problem with my Garmin 550S, except it's critical depth is around 15ft. Below that, zilch.

The conclusion from trying a new plotter and new transducer is that the new transducer fixes nothing ... and the new plotter fixes the problem.

After checking and rechecking this several times clearly the plotter is at fault. The marine engineer I used is of the view that either the 50Hz function of the plotter is kaput, or, the plotter is not switching to or processing the 50Hz signal.

Garmin Technical agree this is a possibility and they're having the plotter back next week for investigation.
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Old 09 August 2012, 21:22   #6
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Leapy: Not working deep, or not working shallow?

The HF side should work well beyond 15 ft; my Lowrance is a HF only unit and I can read reasonably solid to 270 fsw, occasionally (when stopped) to as much as 400 fsw.

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Old 10 August 2012, 03:30   #7
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Leapy: Not working deep, or not working shallow?
Not working shallow
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Old 10 August 2012, 06:46   #8
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Checked all cables and are looking in good condition.

I just don't understand why when reading depths greater than 35' it works fine. I wonder if it's something to do with too much power overloading the transducer or something? I've turned gain and power down with no results. I'm probably going to reposition the transducer in the hull and see if this works better.
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Old 10 August 2012, 07:48   #9
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Garmin 160 c fish finder.
My FF often drops out at 3-5m if I am driving at circa 18 kn plus
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Old 10 August 2012, 07:48   #10
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Andy if the transducer was angled wrong this could be the reason. as the water gets deeper the signal would cover a wider area and the bounceback would also give a wider signal so would hit the transducer. However as you get shallower the signal would narrow and the bounceback might be missing the transducer.

However I will say that I am guessing and this might all be complete bollix ;-)

Before you moved the transducer into the hull did you have the same problems?

Is it a dual frequency transducer. If so can you try setting it to just one frequency to test?

Chris
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