I noticed that the rudder will not hold at high speed. There doesn appear to be any leaks at either end and the reservoir has fluid. I'm aware something has probably gone but want to try bleeding first.
What kind of yacht/boat are we talking about here? What steering system do you have? If your steering system has not lost fluid and hasn't worked on recently, I highly doubt it's air in the lines. The steering ram has a checkvalve or disc (seastar) and they go bad from time to time, which is probably your issue. There are also check valves in the helm too that can go bad.
It's an 88 Ocean 55SS. There was a leak at the autopilot. I tightened the fitting and things seem to b resolved. Will test tomorrow.