Hello, im after some help with the correct auto helm to buy for my boat. She has hydraulic steering. Her weight is 15 tonne with fuel and water. She's been out of the water for ten years and has been all done and is going in the water and then sailing from Brisbane to Cairns sept 18th. Im after any advice on best system to buy so that my gps and other instruments are all part of the same system if that necessary.
Also ideas on installation costs. Cheers

As one of your criteria is that it is all part of the same system as your GPS and other instruments, then you may wish to say what your GPS and other instruments are and what network you have operating between them.

for example I have a B&G (Navico) hydraulic ram (T2 12 volt) operating by mechanical connection to my quadrant, with a B&G (Navico) rudder position sensor and B&G (Navico) instruments. The autopilot computer is also Navico.

The reason I say Navico is that they are also the company behind Simrad and Lowrance as well as B&G, with some gear being the same across the brands, tho' I don't know if that's the case with their autopilots. So different brands doesn't always mean different gear.