Autohelm st50 Tridata Speed problems.

[moresparks]

Hi - have an old ST 50 Tridata -– Depth – Speed/log – Temperature and it only shows around 50% of the speed compared to my GPS. The depth and temperature are fine, I have replaced the paddlewheel for brand new and tried re-calibrating. The Paddlewheel is clean and it’s been like it for years. Normally it is not an issue but lately it starting to annoy me. It’s a standalone unit so “SeaTalk” is not an issue. I have a feeling it may be just calibrating, factory reset or both.
Has anybody have an easy fix for this?
I understand that the Transducers are compatible with the new i50 displays but I won’t get much change out of £500!!

 

[RichardS]

What happens when you recalibrate? I can't remember the details for my ST60 but there is owner calibration and dealer calibration which have different key presses to access. Are you accessing the right calibration mode?

Richard

 

[earlybird]

You say it's been like that for years. Has it ever worked correctly? Is it possible that the transducer is badly positioned?

 

[moresparks]

The Instrument has never given reliable speed data since I have had the boat. In fact it would only read about 10% of the correct speed until I replaced the Transducer which improved it but still a little bit out. The position is in the ideal spot according to the manual. It is possible that the paddlewheel maybe experiencing turbulence I suppose or not positioned far enough down. The calibration is not the easiest to follow, but I wondered that as I have replaced the Transducer a full factory reset and re-calibration is required?
Just wondered if anyone who replaced a Transducer has had to undertake a full re-calibration.

 

[RichardS]

The Instrument has never given reliable speed data since I have had the boat. In fact it would only read about 10% of the correct speed until I replaced the Transducer which improved it but still a little bit out. The position is in the ideal spot according to the manual. It is possible that the paddlewheel maybe experiencing turbulence I suppose or not positioned far enough down. The calibration is not the easiest to follow, but I wondered that as I have replaced the Transducer a full factory reset and re-calibration is required?
Just wondered if anyone who replaced a Transducer has had to undertake a full re-calibration.

You might as well do the full process as there is nothing to lose.

Richard

 

[laika]

When I first got my boat (11 years ago) the log transducer was broken. I believe they no longer made the ST50 transducer and I replaced it with what was available which I think was the one designed for the ST60 instruments. This was compatible but out of the box the calibration was off and it needed a big correction factor. Mine is plugged into a dedicated ("autohelm") speed display but the calibration process is similar and not that complicated. I presume you have the manual? If not it's on the raymarine site (under retired products -> instruments -> ST50).

Unfortunately mine was impossible to calibrate properly because despite apparently being in the optimal position (and where Westerly originally placed it) it reads differently on different tacks, different speeds and different states of heel.

 

[Ink]

It's nothing as simple as the log is pointing forward and not off at an angle?

It doesn't take much, a few degrees out of alignment may make all the difference.

Of you feel you have calibrated everything correctly it won't hurt to loosen the locking collar and move the log clockwise/anticlockwise and see if that makes a difference.

Ink