Follow-up correspondence to an article in Maritime FEEDBACK 51
What the Reporter told us:
I experienced a near collision due to rudder angle discrepancy. The vessel was approaching an anchorage at dead slow speed with a following flood tide, and we applied port helm to clear an anchored vessel ahead. The rudder angle indicator clearly showed port helm applied, and later hard port helm, but the ship did not respond. Collision appeared to be inevitable with the other vessel close to starboard. We put the helm hard to starboard and the ship responded immediately, clearing the other vessel. We then anchored.
The steering gear was not the conventional dual ram type, but a “rotary vane” type. Close inspection did not reveal any way to determine the actual rudder angle. Management were advised, and subsequently we found almost invisible alignment markings showing a discrepancy which we were able to re-adjust. After making adjustments, I was still unable to confirm the rudder angle. Further investigation proved that the bridge rudder angle indicator did not actually show the rudder angle, but the helm angle – misleading at best.
- On any ship, ascertain how the rudder angle indicator actually works, and if it is only acting as a helm indicator inform management, requesting modification.
There is an increasing reliance on technology and therefore a need to validate all instruments on board. A helm indicator is not a rudder angle indicator which records actual feedback. It is vital that personnel confirm the actual angle displayed on the rudder in the steering gear matches what is shown on helm or rudder indicators. In addition, a rudder angle indicator is a Class requirement and must be accurate to +/- 1°.