The unedited letter sent by Derek Gilbert, Raymarine's customer service manager, to YM reader Bob Johnson in response to a question about his ST7000 tripping into standby without warning
Why does my autopilot auto-off?
I read with interest the ‘Ultimate Gear Test’ (YM December 09). I, too, have a Raymarine ST7000 autopilot that ‘trips from auto to standby without warning.’ There is never any interruption of power. A silently unreliable autopilot is an accident waiting to happen. A less than fifty percent reliability score from informed users is simply not good enough. Raymarine should be required to recall all ST7000/7001/7002 control units and – at the very least – fit an alarm which sounds every time the autopilot enters standby mode and which can be stopped by a second manual press of the standby button. Bob Johnson, by email
Derek Gilbert, customer services manager, Raymarine, replies:
Thank you for the feedback from your reader and I hope that we can assist.
Autopilots will only ever change status as a result of some intervention – this may be the manual operation of a control, an external factor or possibly a malfunction. Being microprocessor controlled, an autopilot is susceptible to external influences such as RFI, EMC and voltage conditions, with many of these factors being unobservable to the naked eye. For example, a dip in power supply caused by other equipment onboard starting or stopping can drop the voltage sufficiently to induce a reset in the microprocessor, as a way of protecting the computer within the autopilot. The unit will reset to STANDBY – a safe condition where manual control is immediately restored to the vessel. Experience indicates that fluctuations in power supply quality can be caused by many things onboard, equipment starting or stopping, cabling size and routes, switchgear operating or causing high resistance joints, power management systems onboard, battery charging or condition, etc, etc.., and on long distance cruising boats, power management is under great pressure due to prolonged operation using batteries whilst trying to minimise the use of generators.
Since the general impact of the ‘electronic noise’ on the power supply is to interrupt the normal operation of the computer, it would be impracticable to implement a reliable alarm for this condition, and an unreliable alarm would be unacceptable.
Every responsible manufacturer will advise that all such equipment is an AID TO NAVIGATION and will still require some degree of supervision. Collision regulations also require that the skipper is responsible for the safe navigation of the vessel. A watch should be maintained on board at all times, so that should ANY difficulties of ANY kind be experienced with the vessel, or with ANY equipment onboard the vessel, the responsibility lies with the skipper to ensure the correct action is taken. This overrides any situation and ensures that no matter what has occurred, the vessel is controlled in a safe and appropriate manner. Within the scope of normal watch keeping duties there is no circumstance which would be ‘unobserved’ and therefore the watch keeper would be able to respond appropriately
With regard to the comments in the article regarding autopilots dropping to STANDBY, it is difficult to comment specifically as we do not know what equipment was fitted to each boat (the ST6002 and ST7002 control units can be fitted to any one of our Autopilots manufactured over the past 20years), nor do we know how it was installed or the circumstances surrounding the failure. However, if we had been made aware of the issues at the time, we would most certainly have been keen to assist your reader and to try to identify the root cause.