There is an old rule among regatta sailors that may sound banal, but it gets to the heart of the matter: "Nothing happens without a mainsail". This insight applies at least to all courses higher than half wind, because then a mainsail acts primarily through the inflow of its profile, and only secondarily as a surface that the wind pushes in front of it.
Mainsail decisive for speed potential An optimally profiled and well trimmed mainsail has, more than any other sail on board, a direct influence on the steering behavior as well as the sailing characteristics and is therefore decisive for the speed potential of your yacht. The mainsail is the all-round working sail on board, because while the headsails are changed according to the changing weather conditions, the mainsail always remains hoisted from calm to storm. It should provide the best possible propulsion in any wind force and on all courses to the wind. First, a few basic remarks on the much-discussed topic of sail cuts.
Cross-Cut The most used and proven sail cut is the cross cut. Here the seams run at right angles to the leech chord. It is still the cheapest to produce, robust to handle, and generally the most durable. The disadvantage of a somewhat higher total weight (compared to a radial sail with graduated cloth weights) results from the fact that only one continuous cloth thickness can be processed from the leech to the luff. For strong wind and storm sails, the horizontal cut is in principle recommended, because with these sails it is less a matter of weight reduction than primarily of durability and robustness.
Tri-radial section The tri-radial section is a variant of the bi-radial section with an additional radial section from the neck of the sail. It meets the center and sheet sections. The tri-radial section is an extension of the bi-radial section, in which the web alignment can be optimized according to the line of force. For sails with a low aspect ratio (i.e. relatively long foot in relation to the luff), the tri-radial cut often offers the optimal solution.
In summary, it can be said that a radially cut sail with the same strength, due to the materials used, can usually be much lighter, which has a positive effect on trimability.