In-Hull Type Depth Transducer Giving Incorrect Readings

[Sammy Lou]

I’m having problems with my clipper depth sounder. The display is showing depth readings with a wide range and will not settle nor agree with my estimation of chart depth + tide height.
It’s not a major issue as the boat is a lift keel southerly but if it is fitted I’d like it to work.
The unit was working fine last year but since then the hull has been coppercoated and I’m wondering if anyone has any experience of coppercoat ‘interfering’ with depth transducer readings.
The unit is a clipper duet and the transducer is an in-hull type fitted in a vertical mounted, plastic, oil filled tube bonded to the inner side of the hull. The transducer is located forward and close to the paddle wheel.
Ever since the boat going back in the water the reading has been ranging wildly and indicating a range of depth greater than actual. At first I thought it was just a connection somewhere and I found the co-axial wire badly joined. From here I have ended up replacing the transducer and re-joining the cable via a proper co-ax joiner but the readings are still all over the place but not so far out. Now it seems to be worse in shallow water than in depths.
I’ve read the manual, adjusted keel offsets and gain but do not know what else to do.
Is there anything I’ve missed? Has anyone else experienced a change in behaviour after coppercoat application?

Thanks for any advice.

 

[zambant]

I would guess that the coppercoat is almost certainly the issue as it may be blocking the signals.
You really needed to leave an area under the transducer free of the coppercoat.
Have you tried removing the transducer and carefully hanging it over the side into the water while you are on your mooring? - at least you will be able to check its function.
BUT don't put it in the water so far that it covers the wire where it enters the transducer body.
Good luck
John

 

[NormanS]

I'm not sure if you can just cut and join transducer cables. I know with the ones I've had, the instructions specifically say NO WAY.
Lots of people have Coppercoat A/F, and I don't recall anyone having problems. I don't have Coppercoat, but I do use a copper-rich A/F, which looks, and behaves just like Coppercoat, and I have no problems with two transducers.

 

[pampas]

Have you tried adjusting the averaging function? then adjust the gain function in small increments. best done on a hard flattish bottom, minimum seaweed. that's the way I did mine, then trimmed the unit when on my mooring 1/2 tide soft mud, now give a good nearly accurate reading on muddy bottoms but a bit out on the harder stuff. Better the devil you know.

 

[Stemar]

My Target depthsounder worked for several years through coppercoat until this season, when it started to behave the same way occasionally. I scrubbed off before going off for a week, expecting it to recover, but no. I now have a Clipper that's working fine in the same place, stuck down with a blob of mastic.

You can cut cables. My instruments are mounted in a box that clips to the companionway and can be unplugged to take home. Cutting and joining with a phono plug & socket didn't seem to make any difference. From memory, it's a tuned circuit, so it's the length that matters, though I believe you can but extension leads, so I'm not sure where that leaves my theory!

I forgot to mention that the new transducer didn't make any difference with the old instrument and the new instrument didn't make ony difference with the old transducer, so both must gave got sick at the same time. Go figure!

 

[James_Calvert]

Can't see why coppercoat should make any difference - sonically it's just another hard coating isn't it?

Obviously better if you can isolate your problem to either the transducer plus cable, or the sounder unit. Re the latter, any chance of borrowing another one to plug your transducer into? I don't think it needs necessarily be exactly the same type, just designed to work on the same kHz as yours.

 

[Koeketiene]

I’m having problems with my clipper depth sounder. The display is showing depth readings with a wide range and will not settle nor agree with my estimation of chart depth + tide height.
It’s not a major issue as the boat is a lift keel southerly but if it is fitted I’d like it to work.
The unit was working fine last year but since then the hull has been coppercoated and I’m wondering if anyone has any experience of coppercoat ‘interfering’ with depth transducer readings.

I have the same setup as you.
Likewise we had our boat coppercoated a couple of years ago.
The coppercoat has not interfered with the readings - as accurate as before.

Last year we had a while when, like in your case, the readings were all over the place.
This turned out to be because the transducer was no longer firmly fixed to the hull.
Ordered another transducer fixing kit fom allgadgets and reinstalled - the readings were once again accurate.

 

[stevd]

They do say not to cut or adjust the length of the coax cable. I think if you do extend the cable they do supply one in a fixed length, but they do say basically don't tamper with the cable.

I recently installed my depth transducer as you have yours, and I too had similar issues. I think it was because the transducer was actually touching/resting on the inside of the hull and not floating in the bath of oil. Since I have played around with it set up like that it seems to work. To test the transducer is working I would dangle it into the water as said before allowing the transducer in but not up to / past he cable and check the depth reading you are getting. That will show if there is something wrong with the transducer or the way it is installed. Another way of testing it in the hull, according to the instructions is to mount it directly to the hull on a bed of chewing gum.

Hope that helps