Does anyone know if the Autohelm 100 computer can replace the ST6000 - ie will work with the 6000 control unit, fluxgate, rudder transducer and motor ?
Would you like to elaborate on Autohelm 100 ? What does your manual say it is called ? What colour is you ST6000 head (control) unit ? No this is not a trick question.
The Autohelm 100 computer should run on SeaTalk like the ST6000. You'd need to check what type of drive unit you have - the 100 computer only has enough power to run Type 1 drives, more powerful drives need the 300 computer. You could try looking at Raymarine's question & answer section and, if you can't find the answer, there's an "Ask Raymarine" tab you can click on to send your own question.
Agree entirely and add that the 100/300 manual which is on the Raymarine internet site (forgotten the title of the manual) also clarifies which computer is required for which drive.