How to calibrate rudders ?

[Dave_S]

What is the best way to calibrate your rudders. The swivel at one end of the monitoring actuator broke and I need to replace it. So it could be out.

[Roy M]

Having just done this last week, I can possibly help. First, I assume you are speaking about a rudder position indicator that articulates with your existing rudder(s, since you are possibly a multihull?). Next question, you are doing this to assist with your autopilot? What make and model? These questions are because, depending on your system, the orientation and data input happens in the multifunction display. Some ask you to measure the angles and input them. Some, the digital indicators, actually measure the values after asking you to steer hard over to port, starboard and then center the rudder. You may need someone back in the stern to yell at you when things look centered.

[Dave_S]

Hi Roy

The connecting rod between the rudder and the potentiometer has broken the ball joint linkage so I have lost the setting to align the rudders. I'm hoping there is a clever way to adjust them so they are parallel when pointing dead ahead.

I hope to do it with the boat in the water.

But I think that might be optimistic.

[Roy M]

Dave, this is not going to be a difficult solution, if I understand it clearly. Is it possible to repair the ball joint connection on the potentiometer (rudder position indicator unit)? The potentiometer has the ball, correct? Or is the threaded rod holding the ball? I wish you could tell me the brand and model. The potentiometer may be the challenge because of the articulation of the threaded rod that couples to the steering rod or the rudder post lever arm. It's mostly geometry, the rudder arm (or the steering arm, if it's a double rudder connection.

[Dave_S]

The ball is on the rudder position indicator unit (potentiometer) and the socket was on the threaded rod. The way it broke I can not tell how far the rod was screwed in, I can take a best guess of +/- 3mm (1/8") but that becomes roughly +/- 4°.

The rudders are rotated hydraulically and I can adjust the alignment of the rudders separately to each other hydraulically but need the readouts from both to be calibrated so both read 0 when both are dead ahead.

I'm away from the boat at the moment so I don't have the make/model.

I do have a really bad picture.

[Roy M]

Okay, it looks like a Simrad, but the key is that the plastic part that broke is replaceable, and because of that you need only unscrew it from the threaded rod. There will be no need to adjust, simply unscrew the broken plastic ball cup, and screw the new one the same number of turns.

[Blue Stocking]

Originally Posted by Roy M

Okay, it looks like a Simrad, but the key is that the plastic part that broke is replaceable, and because of that you need only unscrew it from the threaded rod. There will be no need to adjust, simply unscrew the broken plastic ball cup, and screw the new one the same number of turns.

Or, you can put the A/P on standby with the kingspoke vertical, and no helm graduations showing either side of amidships. Install the new rod. Check the accuracy by turning the wheel until the first graduation mark shows at each side. If the degrees of wheel rotation are the same both Pt and Stbd, you are true. If not, adjust the threaded rod until wheel rotation is the same to each graduation.
A side note, I recently had to put a CSY44 A/p out of this mode because when motoring, the prop torque required some helm, -- which was different from the sailing mode. A/P was getting confused trying to keep the boat on course for either mode. Fortunately the ComNav 1101 has a range of quickly adjusted seastate response settings.

[Suijin]

1) Make sure when you replace the connecting rod that you check the length of the new one against the old one. It may have been cut down during the installation. Unscrew both of the ball joints off the new and the old and cut the new rod down to the length of the old rod, if necessary.

2) You calibrate your autopilot through your interface for it. Get the manual for your autopilot and it will describe the process. It's a software thing, not a mechanical linkage thing. Some, like newer Navico, have a very straightforward auto setup routine.

What's the make/model of the head unit /brain of your autopilot?