NASA Depth wiring issue after refit - advice please!

[ganter]

Hi Chaps,

So I have moved my NASA Depth and Log units so they're now flush mounted in the cockpit. On refitting I thought I'd replace the coax plug on the end of the transducer for the Depth unit. Since then I cannot get a reading when engine is off and when on the depth fluctuates wildly from 2 feet to 20 feet.
I've made sure the connection is sound to the transducer cable and new coax plug but something is wrong.
The new coax plug was a buy from the DIY shop for television aerial applications,etc. Should I use something else?
Any ideas?

Many thanks,

 

[VicMallows]

The coax plug is just a standard ordinary cheap TV one. (horrible choice though by NASA). I would suspect your problem is more likely related to an intermittent connection in the 12v supply. If you have an in-line fuse that would be the very first thing I would check.

EDIT: When your engine is NOT running, does your sounder indicate ANYTHING (such as 'out') ? .... and does the LED backlight operate? If so, and your transducer is in an oil-bath, then it may simply need some more oil. (the engine vibration may splash the oil enough to give the erratic readings you see).

 

[ganter]

Thanks for your reply VicMallows.

When engine is off the reading says "E" which is "Echo" but doesn't give a reading. The backlight works and the voltage is okay. My transducer is through-hull.

 

[seadog30]

Hi

Have you checked the 12V supply, is it "clean DC" ?. If you don't have the test gear try connecting a temporary two core cable ( Pos and Neg ) directly to the house battery (i.e. not the battery connected to the engine starter)

If this works ok you have a power supply problem if it still does not work you have a transducer connection problem.

Good luck

 

[ganter]

Interesting. Thanks seadog30, you and VicMallows both say voltage could be the problem. At the same time as I did this move of the Depth and Log I also installed a battery switcher (1, 2, Both, Off). I wonder if that's mucked about with voltages. I have got a tester and will have a look. Prior to the install of the switcher she had a simple two battery set up with 'negative off' switch.

What am I looking for on testing the current from the batteries - both 'engine on' and 'engine off'?

Thanks mate,

 

[tsekul]

Hi,

I saw this thread and hoped some of the posters may give some advice as I have an issue with a nasa duet, log and depth.

Over the winter I ran the cabling through from a pod on the coach roof through to the place I intended to mount it through hull. I since then discovered the in hull fitting and decided to use that as there are enough holes in the hull already! So I got it all setup and ready as they recommend fitting in the water. Unfortunately the in hull pack contains a nut and top cover that should have been threaded onto the cable prior to threading it through the entire boat.

I really do not want to dismantle half the boat just to put a plastic nut and cover on.

I have three options no1 as above, no2 cut the cable and reconnecting, or splitting the plastic nut and cover so they will slip over the cable and using plastic padding seal up the split.

what would you do ???

Thanks in advance
T

 

[VicS]

Hi,

I saw this thread and hoped some of the posters may give some advice as I have an issue with a nasa duet, log and depth.

Over the winter I ran the cabling through from a pod on the coach roof through to the place I intended to mount it through hull. I since then discovered the in hull fitting and decided to use that as there are enough holes in the hull already! So I got it all setup and ready as they recommend fitting in the water. Unfortunately the in hull pack contains a nut and top cover that should have been threaded onto the cable prior to threading it through the entire boat.

I really do not want to dismantle half the boat just to put a plastic nut and cover on.

I have three options no1 as above, no2 cut the cable and reconnecting, or splitting the plastic nut and cover so they will slip over the cable and using plastic padding seal up the split.

what would you do ???

Thanks in advance
T

This is just the echosounder transducer you are talking about ?

I'd cut and rejoin the cable.
Make the cut/join somewhere completely dry and use the best quality coax plug and inline socket that you can find.

 

[Sarnia]

The nut and cover are important to correct fitting, the thru-hull nut holds the thru-hull tight, and the top nut tightens on to the threaded hull fitting, which is directional, I am talking log/speed, if I have got it right.
There is no short answer I believe, start again, cannot see why you need to dismantle so much.

 

[VicS]

The nut and cover are important to correct fitting, the thru-hull nut holds the thru-hull tight, and the top nut tightens on to the threaded hull fitting, which is directional, I am talking log/speed, if I have got it right.
There is no short answer I believe, start again, cannot see why you need to dismantle so much.

Its only the echo sounder transducer that can be mounted "in hull" surely?

 

[tsekul]

Sorry, yes it's only the in hull transducer that is the issue.

I don't think the cover and nut (on the right) are oil tight, only really there to hold the transducer at the correct height.

T