Hello,

My instruments Nexus NX stopped showing the boat speed. Interesting that if I remove speed transducer from it's place and spin the wheel with a finger it shows speed, even low like 0,2-0,5 knots. Then I put the transducer back and go out and speed is 0. There should be nothing on FE bottom that could prevent the water flow especially that I put the boat to water just three weeks ago. There is no visible weed or anything. I suspected cable damage, but there is no visible damage at least. Being removed form it's place the transducer works head up, upside down, on a side, and in a bucket of water. I can just move it inside the bucked with a speed of 0,4 knots.

Has anyone had anything similar with Nexus/Silva transducers?

Alex
s/y Subbota

It happened to us during Baltic Offshore Week in Tallinn, Estonia. The cable broke where it dives into the epoxy that is used to fill the center of the transducer. When you test the transducer, have you tried wiggling the cable?

Due to its construction it was impossibe to fix, so we had to get a new one.

I had this problem once. The reason was that there was some bottom paint in the tube for the transducer. I had painted over the transducer with the dummy in place and some paint went into the tube. It was enough to remove the paint with a finger nail. It seems there is very little clearance between the tube and the wheel, since the paint in the tube was not thick at all.

It could also be a good idea to measure at the other end of the cable. Is the transducer connected to a Nexus server or an instrument? Not that it really should matter which, one pair is +12VDC and ground and the other pair is the signal. One could start by measuring the power/ground pair with an ohm-meter while the transducer is disconnected. Then when connected try measuring DC or AC on the other pair while running and that pair is disconnected.

The server has LEDs blinking if there's traffic on the RX/TX. Or at least the NX2 server has them.

harald wrote:It could also be a good idea to measure at the other end of the cable.

But if it works perfectly while spinning with finger, it can't be a connection nor an electronics problem.

Yes it can, if the cable has an intermittent fault that occurs when in a particular position. But then again, if the transducer is kept in the hand I think one would notice this.

It could also be a faulty instrument, I had a Nexus server that blew its power stage for the wind transducer.

harald wrote:When you test the transducer, have you tried wiggling the cable?

Yes, of course. It seems not to be the case.

Joakim wrote:there was some bottom paint in the tube for the transducer. I had painted over the transducer with the dummy in place and some paint went into the tube. It was enough to remove the paint with a finger nail. It seems there is very little clearance between the tube and the wheel, since the paint in the tube was not thick at all.

I applied the antifouling with dummy plug in the tube. I cleaned the transducer itself so well so it looks like new. There is no antifouling on the transducer itself.

harald wrote:It could also be a faulty instrument, I had a Nexus server that blew its power stage for the wind transducer.

I tried another server already - same symptoms. I have NX (not NX2) system, so the server is called "WSI box" and there is no blinking LED on it.

And it's not a "server" I think, but rather a common bus for all the devices and of course wireless host for wind transducer.

Joakim made a good suggestion. Clean the sides of the wheel with a very fine file, such as a nail-file or smth like that.

harald wrote:Joakim made a good suggestion. Clean the sides of the wheel with a very fine file, such as a nail-file or smth like that.

I already cleaned it very well, but I of course could give it another try. It's much cheaper than a new transducer.

alex wrote:I applied the antifouling with dummy plug in the tube. I cleaned the transducer itself so well so it looks like new. There is no antifouling on the transducer itself.

I have never had paint on the transducer. Only on the tube into which you install the transducer. And also there just a thin layer on the very outer edge of the tube. It took me a long time to realise that it was the cause of the problem.

Joakim wrote:...I have never had paint on the transducer.

Hello

Well I have painted the transducers wheel several times. After the paint is dry I have tested that wheel is spinning whithout problems. The problem starts when boat is in water, the paint is expanding a little and wheel stops. There is not enought clearence between transducers wheel base and the wheel for this expanded paint. It was enough to remove the paint with a finger nail or small pocket knife.

This will not help Alex in this case, but maybe it helps someone else...?

Joakim wrote:I have never had paint on the transducer. Only on the tube into which you install the transducer. And also there just a thin layer on the very outer edge of the tube. It took me a long time to realise that it was the cause of the problem.

I think I now got what you mean and where that paint could be. Will go check it, thank you for the clue.

YES! Round toilet bowl brush for 1,70 did the job very well. With a great help of bilge pump.

Perhaps antifouling paint forms a collar around the transducer pipe edge which swells when in water and blocks the transducer propeller.

Joakim, I certainly owe you a beer.