High Tech Keel with America's Cup Technology: Weldox Inox is a very hard inox that can only be produced by certified companies. The SAPHIRE Weldox structure is produced in Italy only for SAPHIRE. The cost for such a keel is very much elevated compared to an iron cast keel but has big advantages: the profile gets very slim which reduces the resistance in the water, since the resistance increases in the square when increasing speed! This combined with a led bulp provides a very low centre of gravity with low resistance.