Bearing Update after Nacra 17 Executive Call on Wednesday August 16, 2017
Preparing the prototype and setting up the machining has taken a day longer than first expected.
Three prototypes of the new lower bearing are scheduled to be picked up by Nacra Sailing from the supplier on Thursday afternoon. They will be brought immediately to the Nacra Sailing factory for testing.
From the board swap already in progress since the Europeans, there are 15 boards in sound physical condition that have been used by sailors onto the original bearing. 5 of those boards have been examined to determine if there has been any degradation of the boards from being exposed to the original bearing. So far, no degradation has been found, and examination will continue on the remaining 10 boards.
Continued investigation of the failure mechanism with the existing bearing has also been carried out. Under extreme loading, it can be observed that the 1mm lip of the bearing is being distorted in the middle of the bearing. The result is a further exacerbated point loading on the front section of the boards as the full load is being place onto a smaller section of bearing. This also moves the point loading away from the internal webbing which provides the greatest strength. It is believed that this fact is contributing to the breakages, and should be solved by the larger prototype roller bearing solution currently being tested.
*floor is 90 degrees to this frame, displayed as it would be going through the water.
Production of new bearings will continue Friday and Saturday in parallel with continued testing of the bearings in both load testing and sailing. It takes approximately 1 week to produce the 50 sets (100 total) bearings required by the fleet.
Supply of the bearings will be made in reverse order of original delivery to teams attending worlds. The aim will be to have daily shipments as bearings are produced to minimize disruption to the sailors held on shore.
The builder continues to investigate suitable non-destructive testing techniques that could be implemented for all boards prior to the worlds.
“We are working around the clock trying to resolve this issue. We have received input from respected names to aid solving the problem and we apologize for the trouble cause to the sailors,” Gunnar Larsen, CEO, Nacra Sailing.
Nacra sailing, the Nacra 17 Class Association, and the Yacht Club La Grande Motte continue to work toward holding the 2017 World Championship as planned for early September.
