Cita:
Originalmente publicado por guillermogefaell
Hola Panchito1,
Eric es un buen amigo y un magnífico diseñador con gran experiencia en mástiles autosoportados. Mucha más que yo, sin duda. De todas formas a mi no me gusta mucho la idea de instalar un foque en un tal sistema, pues hay que instalar burdas (como se ve) para tensionar el stay y que trabaje bien en ceñidas. Pero esto puede conllevar una flexión excesiva hacia sotavento del palo, haciendo perder efectividad a la mayor. Algo para consultarle a Eric.
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He consultado a Eric este tema y traslado su respuesta tal como él la envía. Prefiero no intentar la traducción porque podría cometer errores en la interpretación de lo que dice.
The running backstays are intended to be used only when you are running downwind, and if you set a spinnaker. Spinnakers will cause free-standing masts to pump, and pumping increases the amplitude of strain impulses, and the frequency of impulses, so you like to keep those to a minimum. Set the running backs when sailing a spinnaker or in any condition when you think the mast bend and/or whipping might be excessive.
Under normal conditions, the mast will bend somewhat, and this is by design. The mainsail should be cut very flat with little luff curve as this will help it stay in shape as the mast bends. If the mainsail is cut too full, then it will invert as the mast bends, so sailmakers have to be aware of this. In fact, this is a hard thing for them to learn as they are so used to cutting sails with lots of luff curve and draft for sails that are fixed to rigid straight masts. A good sailmaker will understand the features of a free-standing wingmast as on the Delft 25 and cut the sails appropriately. I work with some good sailmakers here in the US if you want a recommendation.
The jib should be cut with a slight hollow in the luff to accommodate headstay sag, which will occur naturally, and you want to preserve the sail shape accordingly. Again, most jibs have luff curve in the opposite direction, and too much draft. These sails have to be cut very flat. Most of the drive in the rig comes from the mainsail, and the jib is there to balance the rig and provide a little extra drive in very light conditions. You can experiment with larger jibs if you want. I show the minimum size, but others may want a larger jib, and may add sail area and hardware to handle it.
Supongo que la explicación a lo que plantea Guillermo está en el hecho de que las burdas son volantes (running backstay). Esto también explica algo que no acababa de entender en los planos y es que habla de "active part" y "passive part" en las burdas.
Lo que también entiendo es que hay que ser muy cuidadoso con el corte de las velas.
Saludos y
