ORACLE TEAM USA
Headstay Tension Device
Every sailing day the shore team had to assemble the wing and the platform together with carbon cables. These have fixed length therefore, to install them all, a pre-tension had to be applied in the headstay.
The connection between the wing and the platform is a spherical contact between a ball fixed on the platform and a concave spherical “bowl” on the wing. To maintain everything together, carbon cables called shrouds, two on each side, are attached to the platform. Each of them are symmetrical by position and length. To finish the assembly a pre-tension of 3.5 tons needs to be applied in the forestay cable.
This operation is critical and has to be done as fast as possible because in this situation the boat is very vulnerable to wind. The sailing days are always chosen wisely because of the good wind conditions, as a consequence the assembly operation is done with 5 to 25 knots of wind. The boat and the wing are placed in the direction of the wind in order to have no propelling force generated during assembly. To help the team stabilizing the wing during this tricky phase there is a tank attached to the bottom of the wing (250L).