Originally Posted by
brianb
Do you have any specifics on the rudder load when you are holding the tiller ? Some measurement of this load , or guess and under what kind of conditions ? It sounds to me that you are going to want to go to a hydraulic drive or a very powerful motor drive unit. I believe the later, powerful drives, are available from Jeffa and possibly Alpha. You don't have to use their AP with their drive, nor do you have to use the RM brains with the RM drives. For example, your SPX5 can drive a type 1 hydraulic pump, or with a bit of engineering a type 2. The hydraulics are so powerful and forgiving to shock loads, hence you see it used on so much of the heavy machinery out there. It is less efficient , draws more power per ft lb of output, electrically when compared to an efficient electric drive design. Consider separating your brain's choice from the drive choice. I have used the RM recent brain's and they do a good job of trying to put the boat in the right place given sea state. Their success, like all AP's, depends on the drive's abilities. NKE and BG are true champions for sure, but again no better than the drive.
Good luck with the set up.
Brian