Most probably its the magnetic variation (deviation) that is missing in the RMC sentence when it arrives at the Raymarine
unit. The variation is mandatory for the newer Raymarine auto pilots to work.
There can be two reasons for variation missing (alternatively or even both):
1. Several USB GPS
do not provide the variation. This can be solved
by installing the "World Maganetic Model" plugin in OpenCPN
and activating it. Make sure to get the 2015 version of the plugin, since the modeling behind the last version has stopped working on Dec 31st 2014.
2. Some bridges do not translate the variation to Seatalk
, even if it was correctly included in the NMEA
RMC sentence from OpenCPN
According to Franks answer to my request last year, this is also the case for the gadgetpool bridge:
gadgetPool.de Forums-viewtopic-Variation im RMC-Datensatz für Raymarine Autopilot
Workaround for the SPX computers
for 2nd problem was to send the RMC sentence directly to the NMEA 0183
input of the course computer. Apparently the missing NMEA
input connections of the ACU prevents us from using this workaround.
So if you are acutally able to reprogramm the bridge I think you will need to do so... Good Luck!
And if you succeed please let me know how this can be done, because and I am (still) struggling with the same issue...