Recently installed a 4000 MkII in my 28'' Ericson with wheel steering.
Here are some things to watch out for:
1) Raymarine Customer Sevice through their Internet Website is poor at best. Their answers are curt (when you can get one). Try talking live.
2) The 4000 is recommended for smaller boats (under 18,000 pounds as I recall). Several problems arise: The drive unit will not mount to 3/8" dia. wheel spokes (typical for smaller vessels). The fluxgate compass must be located well away from outside (metallic)influences, but recommended within a certain window of the boat (distance off of centerline and in the aft third). This is difficult at best, and I have been unable to achieve the minimum diviation recommended, irrespective of the location. 3) During the initial trial, I ran into a "No Link" message on the control head and the unit would not function. This message is not addressed in the Manual, and I received conflicting information from Raymarine. Ultimately had to return the new head for service.