Nothing happens without a big one. What sounds so catchy and true is only half the truth on downwind courses. The boat can only develop its full power with a jib or genoa. In fact, the foresail is the main propulsion on such courses.
The mainsail itself only makes a small contribution, but ensures a better flow around the genoa. If the two sails are set correctly in relation to each other, the current is slowed down upwind of the genoa and accelerated downwind. The air flows faster around the headsail, allowing it to generate significantly more propulsion.
Of course, this only works if the headsail itself is trimmed correctly. If it is poorly adjusted, the trim tab effect of the mainsail will not generate any additional propulsion power.
In addition to halyard and sheet tension, the hove-to point plays one of the most important roles in trimming the jib or genoa. Depending on the position of the tack on deck, the force transmitted from the sheet to the sail changes. The lower and leech lines are therefore tensioned differently.
Read in the current issue of YACHT what effects the fore and aft adjustment has on the sail shape and how to optimise the trim for the wind and sea conditions.
You can read all about headsheet systems in YACHT, issue 11/2019, which can be downloaded here or ordered from the DK Shop. Or you can download the article directly via the link below.
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Hauke Schmidt
Test & Technology editor
