Oceanracing 2005- Solo-Around-Nonstop

Solo-Around-Nonstop - Dee Caffari/Aviva
www.avivachallenge.com - zur Übersicht

Friday 23 December 2005 09:00
Shore team commentary Andrew Roberts
Dee solves a serious electrical problem

During the last three weeks or so Dee has referred to working on the autopilot system on a number of occasions.
The problem has been with the reserve autopilot system so whilst it has not affected the actual steering of Aviva, it has become an increasing area of concern because it could have had very serious consequences on the whole Aviva Challenge.

Neue Verdrahtung

Whist we have every confidence in the robustness and efficiency of each system, they are required to work continuously in the most hostile environments so having backup is absolutely essential. If Dee had not been able to solve the problem it would have been very unwise for her to round Cape Horn and start beating to windward through the Southern Ocean. Our only option, in the interests of safety, would have been to advise Dee to give up her attempt to be the first woman to sail single handed round the world against the prevailing winds and currents. That is why so much time and effort have gone into identifying the problem and solving it.

Even though the autopilot system was specially designed to be easily indextained and repaired, modern autopilots are very complicated pieces of equipment controlled by computer processors. In Aviva’s case it is integrated with the yacht’s giro compass, GPS (global positioning system) and B&G wind speed and log. The processor controls an electric motor driven hydraulic pump, which activates a large hydraulic ram, which pushes and pulls a short tiller or steering arm, which turns the rudder. A rudder reference unit tells the processor what angle the rudder has moved to and is also an essential part of the system.

Because Dee is totally dependent on an autopilot to steer Aviva, whatever the wind speed, boat speed, sea state or sail combination, there is a complete reserve system, which can be activated by turning a single switch.
In the event of the failure, of an individual major component, another can be switched in so that, for example, the port system can use the starboard hydraulic pump or if the starboard processor were to fail the port processor could run the starboard system. Having the redundancy facility does complicate the systems further but it is seen as a very desirable option even though with the problems recently encountered it did add to the time taken to find a solution.

Electrics and electronics are, for the majority of people, a highly complicated area to be dealt with by specialist. Very few people would consider opening the bonnet of a new car and attempt to fix an electrical failure in the way Dee has just done. The problem we now know was caused by an intermittent fault in one of the two switches.
Intermittent faults are extraordinarily difficult to find and Dee probably spent sixty or seventy hours identifying the problem by using a multi meter to test continuity and check the voltages across terminals and switches in all the permutations of switch positions.

Actually solving the problem was in contrast quite quick but what was illustrated was Dee’s determination and tenacity. She knew little about electrics and electronics but forced herself to be in all sorts of awkward positions on deck and below deck, endlessly checking cables and junctions with unfamiliar test equipment and solving problems which most of us would have given up on very early on.
Andrew Roberts