Nacra 17 Worlds: Bearing Up Under Pressure
Published on August 24th, 2017
(August 24, 2017) – The long awaited fully foiling Nacra 17’s only began reaching the 2020 Tokyo Olympic campaigners in June 2017, some two months later than initially expected.
The original Nacra 17’s that sailed in the Rio 2016 Olympic quadrennial had a very checkered manufacturing history and Nacra Sailing is trying hard to show lessons have been learned.
So, there were deep sighs, after the dramatic message from Nacra Sailing, on the eve of the Medal Race at the Sailing World Championships Test Event Aarhus (August 7 – 13, 2017) which advised 47 crews not to sail their Z foiled Nacra 17’s until new lower dagger board bearings were supplied, after three dagger board breakages.
There were immediate questions as to whether this would happen ahead of the Nacra 17 World’s scheduled for La Gran Motte, France, on the Mediterranean coast from September 5 – 10, 2017.
Designers Morelli Melvin and Nacra Sailing scrambled to confirm the root cause of the issue and finally determined that a thin section, only a millimeter wide, on the normally unloaded side of the passive lower bearing was applying point pressure to the dagger board when suddenly loaded.
A two-part active bearing replacement, which spread the pressure over a 19mm section was designed and tested, and the component supplier Holland Composite’s CNC machining centers are now producing the replacement bearings.
The new active lower bearings for the Nacra 17 are in production. By late Friday night (August 25) enough units for all those entered in the World Championships will have been produced. 3 machines are working almost 24 hours a day to accomplish the task.
This production run of bearings (for the Worlds fleet) is being produced in a batch process, unlike the prototype parts that were machined one by one. Therefore, all of the parts will become available at the same time on completion of the batch. As a result, all bearings will become available for distribution at the same time.
These replacement bearings will be flown to southern France and hand delivered to anxious crews this coming Saturday (August 26th). The installation of the replacement bearings is just minutes. A representative from Nacra Sailing will fly to La Grande Motte on Saturday with as many bearings as required for distribution there. The installation of the replacement bearings is just minutes work as the Nacra Sailing instruction video shows.
Separate arrangements will be made for teams not in La Grande Motte. Nacra Sailing will be in touch with all entrants to confirm delivery logistics. Nacra sailing, the Nacra 17 Class Association, and the Yacht Club La Grande Motte reaffirm that the 2017 Nacra 17 World Championship will be held in La Grande Motte, as planned.
Source: Rob Kothe