EchoSounder Offset

[Olivepage]

"Drifting away, we are still having no luck getting our NASA target to read when the engine revs are above tickover, although it is perfect under sail. We have ferrite rings on the main power output cable from the alternator and on the power feed to the instrument. "

Sounds unusual, do you have any clever charging or regulation fed from the alternator?

Have tou tried a ferrite bead or perhaps better a ferrite ring with a few turns around it on the lead to the transducer.

Trouble with buying another sounder is that if you don't know the cause it may well affect the new toy.

[Nick]

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The echo sounder worked with the old engine, this problem has only existed since we fitted the new engine.

[Olivepage]

Hmmmm

The logic of that would indicate that the problem lies with the engine or its ancilliaries.

So it may well be the case that any sounder would suffer the same problem, they all work in a very similar way.

Perhaps worth double checking all the earthing connections on the engine and any chargers you may have and of course on the +ve and -ve leads to the sounder.

Only other thought is a decoupling capacitor across the power leads to the sounder, very close to the instrument if you can.

[Rowana]

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The echo sounder worked with the old engine, this problem has only existed since we fitted the new engine.

Nick,

I believe you have the same engine as myself - Beta 13.5HP with the standard 40A (or is it 45?) Alternator. I also have a Nasa sounder, which works perfictly well both under engine & sail. The batteries & sounder are both in close proximity on the Stbd side, and everything works fine.

Sounds like an alternator problem to me.

You could try a capacitor across the supply to the sounder unit, as close to it as possible, but I think that's just trying to fix the symptoms without fixing the root cause.

[Nick]

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Could be an alternator problem, but it's the bog standard Beta supplied one so it is hard to see why.

I just don't know enough about this sort of stuff . . . . there's no other interference with anything from anything, VHF and radio work fine with the engine running.

[Rowana]

I agree that it's hard to se why - Especially as I have the same set-up and it works fine.

It's a pity we're on opposite sides of Scotland, otherwise we could have swapped sounders and see what happened.

I do have a spare transducer which you're welcome to borrow if you like. I can't see it making any difference, but it would eliminate that part of the set-up.

[Rowana]

One other thing has just sprung to mind - Do you have a rev counter on your panel? I don't.

It's fed from the alternator if you do have one.

[ash]

One other thing has just sprung to mind - Do you have a rev counter on your panel? I don't.

It's fed from the alternator if you do have one.

I have the revcounter on mine, and it doesn't cause interference for me.

I fitted all the bits from the Beta panel into one of Steve Birch's stainless steel face plates. I didn't (need to) alter any of the wiring.

Ash

[Rowana]

Ash,

Do you have a NASA Target sounder?

This is where Nick is getting his interference. I'm just trying to identify where his set-up may be different to mine.

It's always difficult, if not impossible, to try and diagnose faults remotely

[ash]

Ash,

Do you have a NASA Target sounder?

No, not a Target. I have just fitted a Nasa Duet so very similar. I also have the Beta 13.5. I also have a Vega. All that I'm trying to do is show where the setup seems similar, and is problem free. Maybe we can then see where Nick's setup is different, and possibly target (sorry) the problem.

Ash

[Rowana]

Ash,

Your set-up seems even more similar to Nick's than mine.

I think we must suspect the alternator, as the sounder was working perfectly well with the old engine. Could Nick have a "rogue"alternator, I wonder?

I think I'd be inclined to double check all the connections (as suggested earlier in this thread), then if that doesn't work, try a different alternator.

Either that or tear my hair out, and I can't afford to loose any more

[ash]

I think we must suspect the alternator, as the sounder was working perfectly well with the old engine. Could Nick have a "rogue"alternator, I wonder?

IIRC - Nick's tacho wasn't included in the wiring package. He had to wire it up himself. I think his words may have been "FTF is the W terminal?" I don't know how he ran the cable but it carries an alternating current, I would be deeply suspicious of it. He could easily pull the connection off the W terminal and run the engine without the tacho to eliminate this possibility.

The other thing that comes to mind is a failure of the diodes on only 1 phase of the alternator - this would tend to give a 'noisy' DC. I think that this is unlikely as this would also reduce the alternator output, and Nick seemed to manage OK throughout his Atlantic trip although he did have to replace his batteries. IIRC he didn't use shorepower at all, though of course he has his windmill, and did a fair bit of motor sailing.

Nick - I'm sure that SteveB could persuade Beta to provide a standard alternator on a sale or return basis. They must have some lying about as they offer the engine with an upgraded alternator.

I would try the following easy tests

1) Connect the sounder to a battery which is connected to nothing else and run the engine.

2) With everything else wired as normal - simply disconnect the cable from the W terminal.

3) Very briefly - because of overheating - run the engine without the fanbelt.

4) Try a different alternator.

5) Try a different sounder.

Ash

BTW - Where is the man himself - he's been very quiet. Is he caught up in the fanbelt or ran aground whilst under engine?

[Nick]

Will try all or some of this.

At the moment the tacho isn't connected as we have the standard instrument panel on. The wire is still on the W connector, but it doesn't go anywhere so I gues that isn't likely to be the problem.

Favourite sounds like running the instrument off a standalone 12V battery whiile the engine is running.

Will keep you posted, but at the moment I have come down with a stinking cold and am feeling sorry for myself . . . .

[DaveS]

Nick,

sorry to hear about your cold - Dr. Simpson prescribes dark rum in copious quantities. (If it doesn't kill the bugs, you won't fee so bad...)

When you're back to thinking about boaty electrics, I would suggest adding another item to your "try this" list. Get a few clip-on ferrites from RS or Maplin. Put them on the cables suspected of causing the problem. This worked well for me when I discovered that fitting my new smart battery charger stopped Navtex reception. (This is the sort of thing that all that EC marking was meant to stop... )

I'm off on my summer holidays later today, hoping to get to the west side of the Hebrides. Of course the forecast is now for lightish winds.

[Rowana]

At the moment the tacho isn't connected as we have the standard instrument panel on. The wire is still on the W connector, but it doesn't go anywhere so I gues that isn't likely to be the problem.

I wouldn't dismiss it as easily as that! If, as Ash says, it is carrying an alternating current, then with one end not connected to anything, it could just possibly be acting as a radio transmitter and transmitting just enough power to upset the sounder, but not enough to upset other electronics like VHF, GPS etc.

I'd remove the wire from the "W" terminal just to be on the safe side.


Also, regarding dark rum as prescribed by DaveS, I'd mix it 50:50 with Crabbies green ginger. It helps me sleep off most cold bugs

But then again, if I have one or three of those, I sleep through most things