Raymarine ST60 Tridata - Speed Log Problem.

[moresparks]

Hi I am hoping someone can advise.
I have a new to me Raymarine ST60 Tridata and the displayed speed is approximately half of the GPS speed despite a spotless clean Transducer.
The Depth and Sea Temperature all looks o/k.
Transducer you say and I would tend to agree but I have mixed test results which is confusing.
I am assuming the Transducer is an M78712 although I cannot confirm this, all the connections look o/k! Spinning the paddlewheel by hand and I get a reading on the display – however the Raymarine test instructs you to connect a multimeter between the removed green and shield connectors and slowly rotate the paddle wheel. You should get an open and closed circuit for each quarter turn – I get nothing!!
I can get a replacement Transducer which is the E26031 I believe, but just wondered if it was a waste of time giving the test results?
Has anybody had similar problems or should I upgrade the whole unit?

 

[earlybird]

Obvious question, but have you calibrated the speed readout against the GPS as described in the manual?
Can't suggest a reason for the lack of pulses when you connect a multimeter, but it must be outputting something to get a reading at all.

 

[pvb]

Spinning the paddlewheel by hand and I get a reading on the display – however the Raymarine test instructs you to connect a multimeter between the removed green and shield connectors and slowly rotate the paddle wheel. You should get an open and closed circuit for each quarter turn – I get nothing!!

Did you try this with the other transducer wires still connected to the power source?

 

[moresparks]

Many thanks for your speedy responses.

I must confess I have tried calibrating but without success – the Speed is so far out the increment values have little effect.

“Did you try this with the other transducer wires still connected to the power source?”
I must confess all other transducer wires were connected at that time – that is something I could try.

 

[[164147]]

Many thanks for your speedy responses.

I must confess I have tried calibrating but without success – the Speed is so far out the increment values have little effect.

“Did you try this with the other transducer wires still connected to the power source?”
I must confess all other transducer wires were connected at that time – that is something I could try.

Sounds like a failure of the paddle wheel sensor - which is also measuring speed through water - not SOG which is provided by GPS.

 

[Scotsailor]

Had a similar problem with a NASA unit and found that the paddle wheel should have had two magnets attached. One was missing. Might be the same with your unit?

 

[petem]

Moresparks, did you resolve this? I have the same issue.

 

[Rafiki]

When I had a similiar problem I found you could buy a new paddlewheeel ; just the wheel and its axle, not the whole unit. that seemed to cure it for me.

 

[petem]

When I had a similiar problem I found you could buy a new paddlewheeel ; just the wheel and its axle, not the whole unit. that seemed to cure it for me.

Was your old paddle wheel damaged in some way?

 

[joybennett]

You can buy a paddle service kit from Airmar which solved our issue -we were a magnet down on the paddle wheel itself. Changed the wheel and cotter pin and away we went !