Sailing knowledge

Head-Radial-Spinnaker
The head-radial spinnaker is the entry-level version for cruising. It is particularly suitable for headwind and room sheeting courses from 180 to 120 degrees of wind incidence. The head tracks are cut radially and thus provide stability. They prevent the lowest point of the spinnaker from moving aft. The remaining courses of the sail are made of horizontal courses in this cut variant. The footrope is cut very round to increase the surface area. This cut is mostly used for light to medium winds. 

Tri-Radial-Spinnaker
The tri-radial spinnaker has become the standard spinnaker. The cloth runs radially from all three corners to the horizontal center seam. This cut variant thus represents a good compromise between shape stability and manufacturing effort. Due to the radial web arrangement from the head and from the clews, the occurring forces are absorbed exactly in the direction of the stronger warp threads.

This load-oriented sail design thus allows the spinnaker to sail higher on the wind and over a wider wind range. It is suitable for courses from 180 to about 70 degrees of windage. The only weak point of this design is the slight deformation of the slightly less loaded cross courses due to the diagonal stretch. Due to its wide range of use, the Tri-Radial Spinnaker is the ideal all-round spinnaker on board.

Tri-Vertical-Spinnaker
The most complex and effective spinnaker cut is the tri-vertical cut. In this shape, the sheets run from the head and out of the clews onto a vertical center section. This load-oriented sail design ensures that all panels with their strong warp threads optimally follow the lines of force in the sail. The cloth panels are divided by one or more transverse seams according to the size and proportion of the spinnaker. This high level of design and production engineering makes it possible to produce spinnakers with maximum shape retention that convert wind pressure directly into propulsion.

The Tri-Vertical Spinnaker is suitable for all courses from 180 to approx. 60 degrees wind angle. It stands up in light wind without distorting in heavy wind. It is easy to trim and very resilient. These outstanding characteristics make the Tri-Vertical Spinnaker the ideal spinnaker for demanding club racers as well as ambitious regatta sailors. Its extraordinary form stability predestines it for the hard regatta use on board.

Source: Moritz Segel