|Dear 49er class,
To address the issue of mast breakages, Julian, as the 49er Copy Rights Holder (CRH), has proposed a new version of the 49er top section. The version you have right now is called ‘TV10’ and the version being proposed is called ‘TV17’.
CST, the manufacturer, has break tested the TV10, the TV11, the TV17 and the Southern Spar tip from the old masts. Julian is proposing the TV17 be adopted as it can bend significatly farther before it breaks in a cantelever test, is only slightly stiffer, yet is only a >1mm difference in static bend (supported at each end) from the current mast
As such, they believe this update will dramatically reduce the number of broken top sections while having minimal impact on performace of the mast. The primary changes to the mast are extending the internal sleeves higher in the section and trimming those sleaves to a point rather than a straight cut. The extension is what adds the stiffness while the cut method better allows deflection before breakage.
Four TV17 top sections have just landed Palma for the fleet to test. We are seeking fleet members to test the sections for us. Please write to John Mcafee if you are willing to do some testing for us. Teams using the masts must submit daily email reports to John, Matt McGovern and Ben Remocker for us to circulate. Hopefully they will perform well from a tuning point of view and we can approve their mass manufacture for the fleet.
CST can produce 4 sections per day, 5 days a week at a peak rate. With 20 weeks to go before the Hague, and wanting to have a replacement to the fleet well prior to the Hague, timing is of the essesnce to make a decision on this. Additionally, there are essentially no more TV10 available to the fleet, aside from those already en route to customers via our dealer network.
The class has not yet recieved a commercial proposal from the builders group and CST we are willing to accept. As such, details of how warranty and replacement is to be handled are not included in this note, but we will continue to review their proposals and let you know once something can be put forward to the fleet.
For clarity and background, there was a lot of work done on a ‘TV11’ as the initial solution, and this tip was even tested briefly in Australia before moving to the TV17. No TV11’s are being used currently.