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Old 04-25-2006, 03:23 AM   #1
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Default Furuno Navnet sounder performance

Hi, I have a Furuno navnet VX2 system with plotter /radar/sounder. When we first got the boat we had an Airmar T256 1KW 50/200 HZ transom mount transducer. The sounder worked well up to 250 feet of water at up to 25knots on high frequency, giving a very good picture of the bottom, and also showing fish. After this depth, the picture would gradually deteriorate, until it lost the bottom at aound 400 feet. On low frequency, it still wouldn't hold the bottom, and the picture was really bad. The Furuno agents tried several different transducers, including the TM 260. The TM 260 was better than the TM256, as you would expect, but still wouldn't hold the bottom at 600 feet, and also returned a bad picture on low frequency. They then decided that the issue was noise from my Evinrude ETEC 200 HO motor. They have now put a 1KW Furuno through hull transducer in the centre of the boat, about a third of the way forward from the transom, to get it awy from the motor. The boat is an aluminium 25 footer. Unfortunately this has made the performance worse, we get a crap picture in shallower water, with gaps in the bottom at speed, and it still wont hold the bottom in deep water. We tried temporarily installing a Raymarine E120 with a transom mount T256 transducer again, and it gave the same results as the Furuno unit on high frequency in shallow water, but held the bottom better in deep water, but only if the boat was stationary. If we tried to move along, even at 5 Knots we lost the bottom. The Simrad guys are claiming if we use a CX44 Nav sation with the Simrad 38/200 Combi transducer, we will get guaranteed single fish detection down to 1300 feet, but the transducer is more than double the size of the TM 260.

Any one have any idea what the problem may be, as the Furuno guys seem to have run out of ideas I have asked them to remove the equipment?

Has anyone used Simrad sounders & transducers, and if so do they outperform other brands?

Dose anyone know if Evinrude ETEC engines could cause any more interference than other brands?

The Simrad guys say a power conditioner would help eliminate any noise issues, anyone know anything about these?
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Old 04-25-2006, 03:02 PM   #2
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Default RE: Furuno Navnet sounder performance

Did your tech guys move the jumper switches on the sounder unit BBF1 to 1kw or did they leave it set to 600kw? My guys forgot to move the jumpers. It is a stupid part of the install on a Furuno sounder but you have to move the jumpers or else you aren't getting 1kw out of it.
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Old 04-25-2006, 03:15 PM   #3
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Default RE: Furuno Navnet sounder performance

They forgot to do it the first time, but it is set to 1 KW now. Dont know why Furuno does this, most machines can sense whether they have the 600W or 1 KW Ducer.
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Old 04-25-2006, 05:23 PM   #4
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Default Re: Furuno Navnet sounder performance

A friend is having the Vx2's w/ 1K T/D installed right now. Where are the jumpers so we can check ? I'm assuming it's just on a black box sounder module, inside that case or external? Thanks.
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Old 04-25-2006, 05:26 PM   #5
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Default RE: Furuno Navnet sounder performance

Well you are now using a thru-hull unit so it can't be the noise issue. I thought maybe the transom mount was installed poorly so you were getting air. However, since you now have a thru-hull is wouldn't make sense unless both installs were just placed wrong and you have some bad luck. The Furuno should give you much better performance than what you are getting. Mine holds bottom without any trouble at speed or on slow troll. Mine is a thru hull 260 glassed in centerline of my hull.

I would suspect you have a problem with the BBF1 sounder unit. I would replace that and see if you have the same issues. In an aluminum boat I am unsure of the need to ground the unit but there is a grounding wire on the BBF1 if I remember right. In any case I would first check to see if you are getting clean water over the thru-hull ducer. Then I would replace the sounder unit with another one and see if it works. The Furuno is one of the best so I would try to find the issue before I went replacing everything. I can't think of anything in the install setup that would give you trouble but it might be worthwhile to re-read the install instructions also just in case it is a setting issue on the Navnet unit.

Sorry just read again. looks like you already tried a different sounder from Raymarine. I think you have some noise from turbulence. I doubt the simrad would do any better. In the same location
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Old 04-26-2006, 01:31 AM   #6
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Default Re: Furuno Navnet sounder performance

T Taxi The jumper is inside the sounder box, just alittle plastic switch.
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Old 04-26-2006, 01:36 AM   #7
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Default RE: Furuno Navnet sounder performance

sigfla, the sounder unit has already been replaced. The water flow over the transducer is ok according to the so called experts. They are grasping at straws and blaming my Evinrude ETEC engine, but I dont think that is the problem at all.
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Old 04-27-2006, 08:22 AM   #8
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Default Re: Furuno Navnet sounder performance

Not to be a total jerk, but if you have had 2 yop of the line systems, furuno and Raymarine put on your boat and they are borh experiencing similar problems. The problem IS your boat. I can't fathom the probability that both systems tried suffered from the same malfunction from the factory, both got into your hands and both acted the same way on your boat.

When my AP was first installed, I got noise on my FF when it was activated. A little rewire was all it took to fix it. I suggest you try the same. Go out and kill all electronics until the problem clears, if it doesn't clear, look at your wiring/boat.
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Old 04-27-2006, 12:49 PM   #9
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Default RE: Furuno Navnet sounder performance

I would get a spare 12v source and connect the system in question directly to the spare 12v source. This would isolate the wiring . Place the source as close as possible to the load. This should give a common point for the grounding. Just a little experiment.
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Old 04-28-2006, 02:08 AM   #10
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Default Re: Furuno Navnet sounder performance

Thanks , RockyW- I found it in the online Furuno manual p.18/pdf p. 26:

http://www.furuno.com/Furuno/Doc/0/G...s%20Manual.pdf
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