Mainsails

The mainsail is what the name implies: the main source of power on your boat, and mainsail development has been considerable during the last few decades. This is the result of new materials and designs.

Also, new materials for the spars and rigging have allowed higher and more efficient sailplans, giving us more flexibility in designing a great mainsail. The mainsail design will need to account for whether the mast is rotating or not, and what style of headsail is generally used on the boat.

At all stages in the design process we are looking for the most efficient airflow over the foils in the same way air passes over foils of an aeroplane. It is all about about balancing the power of the wind with the righting moment of your boat.

The right battens will need to be chosen, as will the cloth while considering weight, durability, and your budget.

We are especially skilled at designing and optimising sailplans around rating rules like the OMR rule, one design rules, and “box” rules like the 8.5 New Zealand Rule.

Our mainsails have generally evolved to squaretop designs which are not essential but are favoured.  Their name comes from their head shape while traditional sails were “pinheads”. This evolution is based on scientific observations of the uppermost portion of a "spitfire wing", an elliptically shaped foil, which generates very little lift because of tip vortexes. If you are limited in the span of a wing, or the height of the spar, you can make the part of the sail that generates most of the drive "longer" by chopping of the top. This is one of the reason for the square ends on the wings on gliders in the 15 meter class - the class rules limit wing span and the shape is intended to do the most within these limits. A squaretop is also favoured because of the area. There is no substitute for square meters of sail, especially in multihulls where righting moment is so great. So with high performance boats and sails you can safely reduce wetted surface area by lifting hulls more easily.