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artemidorus

Hi Derek and all,

some more feedback regarding my wind instruments and mast rotation transmitter (MRT), particularly so that future users of this equipment don't have to go through the process that I went through (and am still going through).

Firstly, the compass deviation manoeuvre required to activate and calibrate the MRT cannot be done without the Compass Hull Transducer (CHT). The digital display unit required to perform the manoeuvre absolutely requires the signal from the CHT. It will never perform the calibration if the heading data is coming only from a SeatalkNG bus via the Microtalk Gateway (MG), even when you can see that the boat heading data is being received by the display unit.

(This meant that my old entry level hull transmitter was incompatible and had to be replaced by the T121 hull transmitter, which is capable of receiving an input from the CHT.)

Secondly, the MG heading data always takes priority over the CHT heading data, so if the MG is active at the time of attempted calibration, the calibration manoeuvre will not work (it never activates on the display unit). The MG must be turned off for the calibration to activate and complete using the heading data from the CHT.

Thirdly, after activation and calibration have completed successfully, if both the T121 and the MG are active, the analogue wind display unit will prioritise and use only the MG heading data, and will ignore the heading data from the CHT. This means that the analogue display unit will not be using the input with which it was calibrated, and so the integrated wind direction output may be way out, depending on the error between the CHT and the SeatalkNG heading data.

I had major trouble until I worked out what was going on, as I had mounted my CHT facing in the opposite direction to my EV-1 "gyroscope" unit, so there was roughly a 180 degree error between the CHT and the MG inputs to the analogue wind display unit. After realising this, I reversed the CHT mounting (put it on the other side of the bulkhead) and performed the calibration again, which (mostly) fixed the problem, although there was still the fundamental problem of the display unit integrating an input (from the MG) with which it was not calibrated. This meant that there still appeared to be quite a bit of inaccuracy with regard to the displayed wind direction, depending on the boat's heading in relation to wind direction.

The solution, in the end,was to fit the Raymarine Wireless Transmitter (T122) with the Actisense NMEA 0183 to NMEA 2000 converter, and get rid of the MG. This was a shame, as the MG is a much newer and neater product than these two older products, and much easier to install. However, now my wind analog display unit is now (I think) always using the heading input with which it was calibrated, even when the EV-1 is active and outputting data through the Actisense converter and wireless transmitter.

I'll pass on my thanks to Raymarine Sydney, who, even though they didn't know any of the above solutions when I first approached them, were instrumental in helping me work them out.

Now the system is almost fully operational. Roughly once every two or three days on the water, the wind analogue display will lose some vital part of its network and read --- for wind speed and lock the direction arrow. This is always fixed by switching the instruments off briefly.

The final ongoing problem is that, with apparent winds forward of somewhere between 60 and 90 degrees, on either tack, the wind direction arrow flips 180 degrees and can remain stably flipped for up to several minutes before flipping back. This is not a problem when helming manually during daylight, but is an immediate major problem on autopilot in wind vane mode, and, I imagine, would be a confusing factor while helming manually in darkness. This problem is bothering me enough that I'll create a new thread for it.

Nick
F-32 "Amazon"