The main sail is always in use when sailing, meaning it has to cover a wide spectre of wind angles and forces. The shape in the main sail consists of three elements: A designed shape, the stretch of the material and the shape of the mast. Combining these three elements makes the finished product.
Softer (often woven) materials stretch more than laminates or membranes/ EPEX do. This means that softer materials perform better over a larger range of wind condition, where the harder ones are more specific. While sailing, the mainsail is connected to the mast, and usually the boat also has a backstay. A tight backstay will bend the mast and depower the main - good in a heavy breeze, while a straighter mast gives you a deeper and more powerful sail, which comes in handy in lighter conditions.
We have all types of mainsails in our portfolio, from cruising conventional mainsails in crosscut woven materials that are suitable for coastal sailing in different materials and cuts up to our lightest and most stretch resistant racing sails. Mainsails can also furl into the mast or boom. These sail types can be delivered with or without battens. Full battens will improve the boats performance for two main reasons. The battens obviously support a positive roach that result in a larger sail area than if not battens are used.
The other big advantage when using full battens is that these will work as reefing points. When you furl the sail so that the batten is close to the extrusion, the luff will be stretched, and you have a flat and efficient reefed sail.
Multihulls as well as some monohulls are equipped with so called “fat head” or “square head” mainsails. This design adds sail area, and another effect of the wide top is that they are aerodynamically more efficient in most conditions. These designs do however not work unless your boat either does not have a backstay or is equipped with double backstays where the leeward one is loose, so it does not conflict with the leech of the sail.