I had a conversation with the manufacturer of Yakbitz products, all the products are designed and made here in Qld. I am going to give there Seatalk1 (ST1) to NMEA bi directional wifi/usb bridge a go. It will convert all the ST1 info to nema0183 (and back again) plus connect the nema0183 data from the AIS and send it all out via wifi or usb. All I have to do is splice it into the existing cables at the back of the current chart plotter, which will still be fully operational for radar and redundancy.
I should be be able to have everything from the legacy raymarine system, except radar, available on a laptop (at the nav station) and android device (at the helm) and also be able to control auto pilot direct from those devices. Sounds good to me and very inexpensive plus its Aust Made.