Regarding Autopilot pump adjustment:

Information, below, from two emails sent by Randal Johnson (4625).

Hi All

This summer the primary autopilot pump motor failed on Dora Mac while we were in Indonesia. The manufacturer said the pump was too big for the cylinder and suggested a continuous run pump. Bill replaced it and suggested I try resetting the flow rate on the pump (Adjusted by rotating a collar on the front of the pump motor - BK) . The steering manufacturer suggest a rudder stop to stop time of 15 seconds. The new pump arrived with the adjustment at full flow and the rudder would go from stop to stop in 8 seconds. With the adjustment at the other extreme it would take 22 seconds. I adjusted it to 16 seconds stop to stop. The secondary was set up at full flow and I adjusted it as well. The pump I removed was set at full flow and I believe that contributed to it's demise.

The Octopus pumps have a flow adjustment built right in to the pump/motor mounting. These pumps are shipped with that adjustment at full flow. The installation instructions recommend a rudder stop to stop speed of 15 seconds. With the adjustment at full flow, mine would go stop to stop in just eight seconds. With the adjustment moved all the way in the opposite direction the speed was 22 seconds. I was able to adjust it right to 15 seconds and then I adjusted the backup autopilot the same.
This is a very easy adjustment. If you have a ComNav like I do, just push the buttom "P" for power steering. Using the arrow buttoms move the rudder from stop to stop and check it with a stopwatch to see the speed. It needs to be as close to 15 seconds as you can get it. The pump is attached to the motor with two screws. One has a slot which allows you to rotate the pump. One way reduces and the other increases the flow.
Though I installed and adjusted the new pump back in December, yesterday was the first time I had seen it work. We moved the boat from Sebana Cove to One 15 Marina in Singapore and I used the autopilot most of the way, turning it off to dodge ships as big as mountains numerous times. The autopilot performed much better. Even when I reengaged it, it would find the heading with just one counter-adjustment. Before, the pump would run in opposite directions three or four times.
With the adjustment at full flow and connected to the cylinders we have, the pump runs too much. Everybody check theirs.

Randal
In Singapore

Note: The sea-state and counter turning adjustments should be set to allow a bit of hunting. Adjusting for very precise control adds a lot of stress to the pump.

I made the adjustment to the primary and secondary pumps. A big improvement.

Thanks again to Bill and Randal!


Hugh

On the way over to Subic it was a bit rough and I noticed the pump ran virtually all the time.

I adjusted both of mine and as shipped they both were WFO at 8 seconds. I fiddly job with a bit of leading hydraulic oil buy once you jam yourself in the cubbyhole it is pretty easy. I adjusted the potentiometers, and pilot working range at the same time.

I agree with Randal and Bill on this. The 8 second lock to lock time is too fast. With the larger rudder even small corrections are quickly noted, this causes the auto-pilot to see-saw back and forth.

I haven't made the change yet but I had noted the problem. Thanks to Randal and Bill for posting this information.

Hugh

The large Octopus pump is correct for the BA-200 Capalano cylinder. Constant running pumps are great, however they are expensive and power hungry.

The large pump set at 8 second lock to lock, coupled with the large Diesel Duck rudders, means the minimum correction that the pump can make results in an over correction. Which keeps happening over and over stressing the pump. ComNav recommends 15 seconds and this seems to work well in my opinion.

This does not sound right!
If the pump fails it is more likely that it is too small for the cylinder, and not the other way around.
Many factors affect steering. One of them is proper matching of cylinder volume and pump capacity; ultimately, however, it is the design of the underwater profile of the hull and rudder, proper rudder angle (full 35 degrees to port and starboard, or slightly more - but not less)and rudder balance.
The latter cannot be changed. So you are left with the former: cylinder volume, pump capacity and rudder angle.
I would not want more than 8 seconds (or 3 to 4 turns by hand) lock to lock. This makes maneuvering in close quarters much easier, but more importantly, it will help to keep the boat under control in heavy (following) seas.
The autopilot pump should be able to handle this.
For serious offshore cruising with a heavy 462 DD I would want a continuous running pump.

Jurgen (formerly DD4403 Nomad)