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Ljungström sailboats were created by the Swedish engineer Fredrik Ljungström, who was interested in sailing since childhood. A "Ljungström sailboat" typically has a and a . A Ljungström rig mast has no mast stays. The mast rotates on two ball bearings often flying double mainsails, with no foresails. In their time the Ljungström sailboats were a minor revolution as they were fast, safe and easy to sail as well as relatively easy and affordable to produce.