Autopilot System for Sailboat

[taobsu]

I don't know much about sailboat. Here is one question: Is there any cheap autopilot system exist for sailboat? And how it setup with existed mechanical steering and sail manning system (not hydraulic ). I am talking about for island hooping in inland lake, not those for open water offshore cruising.

The autopilot for power vessel is relatively easy to archieve. On the other hand for such system work on sailboat, I guess it has to measure the factors such as ever-changing wind speed, direction, as well as position (GPS) and chart information.

I can think of such system exist for big/super yacht, and they can be very expensive. What I want to know is that if there is any reasonablly priced autopilot system for mid/small size yacht, especially for catamaran in 40'~50'.

I am dreaming to have such a cheap autopilot system which can guide me to marina/dock based on the GPS coordinates I entered.