Rudder centre

[Wayne]

I recently had a below deck autopilot (Raymarine) professionally installed. The previous owner had marked the centre of the rudder with tape on a spoke on the wheel. Using the autopilot a couple of weeks ago in a blow I felt that the "centre" had shifted a few degrees. When I checked  it appears that the centre is now a few degrees off the mark on the wheel. Had the person who installed the autopilot test the system and he says that nothing has failed. So, two questions:
1. Is rudder centre always aligned to centre spoke on wheel?
2. Any ideas on if there is a problem with bearing etc?

Any ideas appreciated.
Wayne

[dawntreader]

The autopilot drive to the helm wheel is via a 'bicycle' chain, tensioned by a bottle screw, in the binnacle. If this is not correctly tensioned then this could cause a minor deviation from centre. There are two chains which move with the wheel, one for the autopilot and one for the steering mechanism - both should be equally tensioned or there will be some movement in the wheel before it 'bites' one of the chains. However, do not over-tighten them. When tensioning be sure to move the wheel backwards and forwards as the chain will only tension on the side of the screw initially.

I am not sure, but I doubt that worn bearings would cause the same problem - especially if the deviation is only to one side.

[Symphony]

The autopilot drive to the helm wheel is via a 'bicycle' chain, tensioned by a bottle screw, in the binnacle. If this is not correctly tensioned then this could cause a minor deviation from centre. There are two chains which move with the wheel, one for the autopilot and one for the steering mechanism - both should be equally tensioned or there will be some movement in the wheel before it 'bites' one of the chains. However, do not over-tighten them. When tensioning be sure to move the wheel backwards and forwards as the chain will only tension on the side of the screw initially.

I am not sure, but I doubt that worn bearings would cause the same problem - especially if the deviation is only to one side.

What you are describing is the Lewmar drive. The Raymarine drive is a ram directly onto the quadrant.

The centre of the rudder does not always correspond to a spoke as it depends on how the cables are adjusted (if it is cable steering) or the tie rods if it is rod steering.

[tony from dorset]

Had same problem on my bav 36 last year  as the year progressed it got worse, sent the coarse computer back to raymarine they updated software and was refitted and sorted.  noticed this year its a couple of degrees out again. i checked and eliminated all other things only left the coarse computer, cost at raymarine approx £95

[Ziffius]

Just a thought, have you checked the rudder centred visually from below the water to see where the wheel position is to correspond to that - easy in the warming med sea, not sure about down under.

[Wayne]

Thanks for all the replies. As it is summer in OZ have had a swim and the rudder appears slightly "off centre" if you align rudder and the spoke that originally marked the centre. Have been away in your hemisphere on holidays for 6 weeks so will check out the new alignment marking against autopilot.
Wayne