(The information on this webpage was presented at the HISWA Symposium in Amsterdam in November 2004)

On this page the development of a new design tool is discussed. Current design tools do not allow for further optimisation of sailing yacht rigs. This is due to the fact that they are based on a simplified statically determined model of the rig and the use of relatively high and often not traceable safety factors to take into account several design uncertainties. Lowering these factors may result in particular cases in unsafe rigs.

stresses in the mast on the top of the mast, predicted by Best Mast	stresses in the mast up till the first spreader

To be able to design lighter and reliable rigs in aluminium and carbon, a more sophisticated model for the structural behaviour of a rig is needed. Only a non linear finite element analyses can provide a prediction of this behaviour. This requires a reliable input of the external forces acting on the structure. The loads determined by the current design tools are not detailed and reliable enough for this purpose.

A new design tool, Best Mast, has been developed. The tool consists of the finite element analysis program MSC.Marc^® Mentat^® and a sophisticated load model. Due to specially developed user interfaces for the input of mast and yacht data the result is a very generic rig design tool. The role of the Lightweight Structures B.V. was to develop a load analyses method to determine the loads for the finite element module. The load model is based on a Velocity Prediction Program module (VPP) and a force translation routine. The VPP determines the total driving and heeling force as generated by each sail individually. These are subsequently translated to forces acting on the rig like a distributed force on mast and fore stay, halyard loads and boom and pole loads.

At this stage the Best Mast tool can predict the response of the structure on static forces from the sails. A next step is to develop a structural model for the response on the dynamic behaviour of the yacht. Until then dynamic safety factors are used derived with full scale measurements in combination with the design tool.

Please read the paper (15 pages, 4 MB) about Best Mast!