NASA Digital depth sounder

[donm]

I had problems with this throughout the season - sometimes reading ok, sometimes false and sometimes it showed "Out" which according to the manual means no signal. Not sure which part is the problem as the head is reading signals, and I can hear a clicking where the transducer goes through the hull, so something is happening at that end too.

Boat is ashore now. Anyone have any ideas how to test it in-situ, as I do not wish to disturb the transducer hull installation unless I have to and, if I do remove it then I might just as well replace it?

 

[Seajet]

I have found both the Target and Clipper depthsounders to be the best ( could say only useful ) things NASA make !

Presumably you've checked the connector between transducer and display, not just wiggled it tight but also checked the grip on the co-ax, and ensuring there's no corrosion there ?

I seem to remember there's a way of testing a through hull installation with a bit of tubing underneath, someone with a better memory will be along in a sec.

 

[donm]

I have found both the Target and Clipper depthsounders to be the best ( could say only useful ) things NASA make !

Presumably you've checked the connector between transducer and display, not just wiggled it tight but also checked the grip on the co-ax, and ensuring there's no corrosion there ?

I seem to remember there's a way of testing a through hull installation with a bit of tubing underneath, someone with a better memory will be along in a sec.

Thanks and Yes - they do have a good reputation. I have looked at the joint and although it is not spotless it is pretty much as expected.

 

[erbster]

Mine behaves like that too. In my case, I think that I did not mount the transducer far enough below the water line to take account of the boat pitching and/or turbulence from the bow wave. I wanted transducer at front of boat, but (due to diminutive size of boat) cannot conveniently mount it any further back. I decided to live with it, as it works well enough in shallow water.

 

[LittleSister]

Aside from the possibility of a poor connection, adjusting the gain and/or sensitivity threshold may help resolve false readings. You can download the relevant manual if you don't have it from http://www.nasamarine.com/downloads.php

If checking the basics doesn't resolve the problem try calling Nasa for advice.


p.s. Just found this in the Frequently Asked Questions bit on their website:
Q My depth sounder is showing erratic readings
A Check the transducer is installed correctly, hang the transducer over the side directly into the water, it should work perfectly this way. If mounted in an in hull kit ensure there is enough oil in the tube, the transducer face should not touch the hull.
A Turn engine/charging system off, if readings settle its likely to be alternator or spark plug 'noise'. Fit suppressor to alternator/fit suppressor spark plugs.
A Turn all other electrical systems off, operate depth sounder in isolation, if readings okay turn one systems one by one noting which is causing the RFI (radio frequency interference). Suppress the offending item at source.
A Check the depth sounders 'GAIN' setting

 

[IanphotoJ]

Just joined ybw and have similar problem with Nasa depth. Okay under sail but jumps all over under engine. Not helpful on the East coast. Thanks for the suppressor tip. Coud be the answer

 

[nigelmercier]

... they do have a good reputation...

Has this thread drifted already?

 

[H4B]

Have you got vegetable oil between transducer and hull? Absence causes symptoms you describe.

 

[PhillM]

A Turn engine/charging system off, if readings settle its likely to be alternator or spark plug 'noise'. Fit suppressor to alternator/fit suppressor spark plugs.

Mine worked OK until I put the new engine in. Problem is I have no idea what a "suppressor kit" id, where to get on and how to fit it?

Suggestions please

 

[donm]

Have you got vegetable oil between transducer and hull? Absence causes symptoms you describe.

Thanks but it is a through hull installation

 

[donm]

Aside from the possibility of a poor connection, adjusting the gain and/or sensitivity threshold may help resolve false readings. You can download the relevant manual if you don't have it from http://www.nasamarine.com/downloads.php

If checking the basics doesn't resolve the problem try calling Nasa for advice.


p.s. Just found this in the Frequently Asked Questions bit on their website:
Q My depth sounder is showing erratic readings
A Check the transducer is installed correctly, hang the transducer over the side directly into the water, it should work perfectly this way. If mounted in an in hull kit ensure there is enough oil in the tube, the transducer face should not touch the hull.
A Turn engine/charging system off, if readings settle its likely to be alternator or spark plug 'noise'. Fit suppressor to alternator/fit suppressor spark plugs.
A Turn all other electrical systems off, operate depth sounder in isolation, if readings okay turn one systems one by one noting which is causing the RFI (radio frequency interference). Suppress the offending item at source.
A Check the depth sounders 'GAIN' setting

Thanks. I'll have to wait until afloat to check these but would like to test the transducer now if possible

 

[KevO]

Thanks. I'll have to wait until afloat to check these but would like to test the transducer now if possible

If it keeps bl**dy raining you might soon be able to!

 

[Seajet]

I can't help thinking transducers themselves are long established kit and rarely fail, so installation / wiring & connections / display unit seems more likely; if you're sure about the wiring it might be worth asking NASA how much if you send it to them for a check ?