The rig differs from conventional rigs in that it is a free-standing mast and "swing-rig" with an unusual headboard, which has been called the "turret". The turret enables larger sails to be fitted to produce more power. Being an unusual rig there was much debate on defining the design loadcases. Carbonworks developed several draft loadcases and commissioned two other companies to do the same. These loadcases were developed using non-linear rig models from specialist sources. Over a period of two months this information was compiled and compared until a final design loadcase was settled upon. The critical loads were determined to be ultimate mast compression and forestay catenary tension. Ultimate load was developed at 40 knots apparent and full sail of 120 square metres. Ultimate load is intended to be when the mast breaks. This represents a mast compression in the order of 25 tonnes and a distributed load down the 20m mast of 2N/mm. The turret transmits the full compression load from the rigging to the mast, and is consequently very highly stressed.

Parallel to this work, draft material specifications were developed from information provided by the material suppliers and the preferred fabricators. The mast was made as a pressure moulded component and the turret is to be made as a shrink-wrapped consolidated, wound mandrel piece. Draft material specifications were used to produce preliminary mast and turret models. The turret had a target weight of 60kg. The draft turret model showed this was feasible, so the turret design was developed further resulting in a 57kg component. The LUSAS Composite modeller proved to be very capable in allowing changes in specifications and geometry to be implemented rapidly. Some designs were imported from Autocad and Cadkey drafting packages using the IGES translation and import facility. Tsai-Wu and Tsai-Wu-Cowin theories were used to determine First Ply Failure situations. Linear buckling analysis was used to ensure that mast and turret buckled at a load factor of 1.2 or greater.

The turret is 6m long, approximately 230mm in diameter, and made from prepreg carbon fibre. The turret was modelled in LUSAS Composite using semiloof thin shell elements and consisted of laminates with 7 to 22 layers. The turret has several holes for halyards and control lines in areas of maximum compression. LUSAS Composite was used to determine if these holes contributed to premature buckling, and to assess how much unidirectional carbon fibre was needed each side of the holes to act as a bypass for the loadpath. In addition, the attachment points to the mast are slender webs and LUSAS Composite helped determine their minimum thickness to prevent buckling. The design cycle consisted of building a very thin model of about half the target weight, based upon hand calculations. Linear buckling analysis was done to determine where it would fail. The failed area was thickened, then run again, usually moving the buckle to somewhere else. When the model was failing at about a load factor of one, a stress analysis was done to check the stress regime. Some areas had to be reinforced due to overloading, either by ply orientation changes or using more sublaminates in patches.