L470 reads 2.0 feet!

Old 07-26-2004, 12:17 PM
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Default L470 reads 2.0 feet!

Help! I have a Raymarine L470 fishfinder with bronze thru-hull transducer. Anyone ever have their fishfinder just read 1.9 - 2.1 feet? Temperature and speed work fine. I tried performing factory reset to no avail (per manual and Raymarine), and shipped the unit back to Raymarine for service - they said it worked fine.
After re-installing, I turned it on and it read the correct depth (35 feet in sand) per the chart for the area I was in, in auto mode showing proper contours with surface and fish symbols. Yea!
I looked about 15 minutes later, and the unit was back to reading 1.9 - 2.1 feet with no bottom! It had switched to a 5 foot range. I switched to manual range to 80 feet, manual sensitivity (low) and I was able to get a bottom line at 35', but no surface line or fish symbols, and the depth read 1.9 -2.1 feet.
The unit is only 2 years old with very limited use.

Any ideas?
Thanks! FlukySue
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Old 07-26-2004, 12:34 PM
Join Date: Mar 2004
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Default RE: L470 reads 2.0 feet!

FlukySue, after the re-install and the sounder read correctly, did you drift for the next 15 minutes or were you underway. If you were just siting and drifting in the cirrent with the echosounder operating, I'd suggest that you have air-bubbles on the transducer face. E Fitz.
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Old 07-26-2004, 12:52 PM
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Default RE: L470 reads 2.0 feet!

Yep, sounds like the spot you have the ducer may not be the best spot. Is it always in the water, does it NOT have any air bubbles or turbulent water under it? Is it too close to your prop or lower unit...?? Are you in REALLY dirty water? The water in my river where I dock is VERY dirty, and always shows at 2' on the FF, beacuse it is about 4-6' deep but so muddy the FF thinks it's shallow.
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Old 07-27-2004, 11:35 AM
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Default RE: L470 reads 2.0 feet!

Thanks guys!
I waited to turn the unit on after re-installation until we were in the ocean with extremely clear water clarity (amazing!) over a sandy bottom. I turned it on after the boat was stopped, the engines were off, and we were drifting. Then we continued to drift. I was happy to see the unit appeared to be working correctly, at least for several minutes.
The boat is a Pro-Line 2950 with twin outboards - the transducer is located 5-6' forward of the stern, and was installed by the dealer when new with a fairing block, about 4-6" from the centerline. It is always covered by water, even when on plane.
Every year, I lightly sand the transducer and apply 2 light coats of the MDR transducer antifoulant. I'm wondering if I should have the boat hauled, and remove the antifoulant with mineral spirits???
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Old 07-29-2004, 10:26 AM
Join Date: Aug 2002
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Default RE: L470 reads 2.0 feet!

I have an L750 that will "freak out" occasionally. In 40-90 feet of water it will read less than 3 feet, then go back to normal reading. I use an in hull puck. Only does is once in a while...
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