Arne wrote: Note: When I draw sails nowadays, I often draw them with the halyard span pointing 15 degrees aft of the vertical mast. This lets one shift the sail a bit forward or aft to optimize steering balance.
As masts are frequently raked forward, I feel that the phrase “the vertical mast” carries the risk of confusion. Unless the reason for Arne’s good advice is actually understood, that phrase might result in someone making a poorly designed halyard arrangement. Evidently one of the issues arising from halyard angle is gravitational force on the sail bundle, which is vertical, regardless of the attitude of the mast.
It is not easy to find a simple way of better expressing this advice of Arne’s.
With respect, could I suggest the following: “…the halyard span pointing 15 degrees aft of a vertical line through the halyard crane…”
Another thought, based on problems I have been able to solve on my own rig – I would have thought that 15 degrees to the vertical ought to be the about the maximum desirable halyard angle, and that if one expects to be able to shift the sail forward or aft in order to optimise steering, perhaps a starting point for the halyard angle should be less than 15 degrees, if possible?
However, with my rig I don’t have the luxury of being able to shift the sail forward or aft so I am speculating here, and perhaps Arne will clarify.
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Here is my advice to Niko, as one amateur to another: Arne is dead right in suggesting that you do not try to over-think all of the issues, some of which are possibly unknowable anyway, unless you are willing to just give it a try.
Well designed and proven rigs are readily available and should be the starting point for your first sail. These proven rigs should be considered as a package – a package of compromises which has proven to work very well in practice. (David has hinted at something along these lines when he wrote, for example: “It's certainly important to consider the P/B ratio, but not at the cost of losing sight of other factors…”)
As a first-time sail maker, choose a planform which suits your boat – be it one of Arne’s, or a Weaverbird style, or whatever, there is a wide range to choose from now – then follow the advice of the designer and implement it as a complete package. After that, when you make your next sail, that will be the best time to give rein to your creative thinking.