Nasa Target Echo Sounder

[cliffsorge]

My Target sounder is flashing erratic depth readings up and down all over the place, could this be a failing transducer, electrical noise or something else???? I also seem to have an E constantly on the display does this mean error?

 

[oldharry]

Most likely to be electrical noise. Was it working properly before? If so have you added or moved anything? The transducer cable should not lie along side other cables, particularly those carrying VHF or log signals.

The E almost certainly means the echo sounder is aware that something is wrong and is telling you not to rely on it.

To start with turn off absolutely everything else, and see if the display stabilises. If all is now well, turn things on one at a time until the display breaks up, starting with the engine. A developing alternator fault is the most likely cuplrit for the symptoms you describe.

If the display is still erratic with everything else off, check the unit connections, and try a drop of WD40. Remake the 12volt supply connection, and work the transducer connection in its socket to remove any dirt or corrosion.

Is the Transducer cable damaged in any way? If so a new transducer will be needed, as moisture in the cable will be causing problems.

Good luck!

 

[brian_neale]

Is this new behaviour on a sounder which used to work, or has it always been like this?

I had one of these sounders in my last boat which gave similar symptoms. The E means that it has lost the echo, and in the case of my boat meant that there were bubbles in the oil bath which held the transducer. I added a little more oil, and sloshed the transducer around in the oil bath. That more-or-less fixed the loss of signal problem, and it was good for 50m depth after that (might have been better, but that was the deepest water I ever met!). The erratic readings I eventually traced to disturbed water. It almost always happened when I was crossing the wake of something power driven, of any size, and even some minutes after it had gone by. The sensitivity of the electronics was such that it could not distinguish between the echoes from propellor wake and a real sea bottom.

Your problems may be completely different, of course, but these may give you some areas to investigate.

 

[LadyInBed]

If the transducer is through the hull, it could be a build up of weed / crud on the bottom of the transducer.

 

[cliffsorge]

Many thanks for the advice I will give them a try, I don't know if its ever worked as I've only had the boat for 6 weeks!

 

[philip_stevens]

Send an email to

ALAN
nasamarine@kbnet.co.uk

He should be able to put you on the right track.

Also have a look at their website - http://www.kbnet.co.uk/nasamarine/target.htm - and from what I can remember when I had these instruments in my last boat, the sounder always shows an E - to show it is the echo sounder and not the log.

regards,
Philip

 

[Plum]

Cliff, I have one of these echosounders, and contrary to what others have said, the "E" does NOT mean there is a fault. The E is always there and it just refers to "Echo".

You will always get a little jumping about of the numbers, often worse in shallow or silty water, but you can reduce the jumping by changing the sensitivity of the instrument. Press the "set" button and you should get a number on the screen (between 1 and 5 if I remember correctly), then using the other two buttons below the "set" button, change the number to a higher or lower value (you will have to experiment) and then press the "set" button again to revert to the Echosounder function. I assume you have not got the instruction book as this is explained in it.

 

[tome]

WD40 is an insulator so never use it on electrical connections! use Isopropyl alcohol instead, available from proper chemist shops

 

[davidphillips]

I had the same problem. Wrote to PBO who published my letter last July under the technical problems section. Also contacted NASA who swapped my target for a clipper on payment of an additional £90 or so. Basic problem is that the Target is a cheapo instrument which easily gets 'confused' by false echos.

 

[oldharry]

WD40

I know, Tome, but it works! And its much more easily obtainable than IA or proprietary Contact cleaner sprays!

Particularly good on cruddy starter battery terminals as a 'get me home'

As with any 'get me home' it needs to be followed by a 'proper' repair - cleaning up, replacement etc when not bedevilled by the wind and waves and a faulty wotsit.....

 

[Guest]

I think Brian is more than half correct.
My transducer sits in a bath of liquid paraffin and unfortunately over the course of a season it leaks. Once the air gets below the face of the transducer, the instruments produces erratic readings. Filling the tube around the transducer with liquid paraffin instantly solves the problem.

The E signal is normal - as reported in other postings.

When I cross the wake of the IOW ferry the reading are also erratic for a minute or so. Think this is due to aeration.

It will show depths greater than 50m. as I have clearly picked up the Hurd Deep (N. of Alderney) on several occasions.
You get what you pay for in this life, but if you make sure the panel is well sealed, the Nasa instrument will give good performance for quite a few years.

 

[Joe_Cole]

I had exactly the same problem recently with my Target sounder and it still continued when I had a new instrument. In the end it was down to engine interference being picked up on my solar cell! Disconnect it and I find the new instrument works perfectly.

I had some postings about this about 6 weeks ago.

Try the sounder with the engine switched off. If it improves you're on the way to resolving it. It is very frustrating trying to pin point a fault like this!

Joe

 

[roger]

My Target is only so so. It is badly affected by military signals. I went through exercises off Plymouth 2 weeks ago and was getting a depth reading of 2 metres in mid channel. I've also had the same thing in Norway near a signal station.
You are much more likely to get problems if your transducer is inside the hull and sensing through it especially if its a thick hull. Do follow the advice in the installation instruction about finding a good bit of hull by attaching the transducer with chewing gum.
Its nearly always fatal to mess with the cable on any of these instruments. Salt water wicks yards along the sheathing which then rots.