Join Date: Feb 2000
Location: Annapolis, Md
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gaff rigged? Full Battened Marconi?
There are a lot of reasons why Gaff rigs are not as weatherly as Bermuda rigs. To being with going up wind is always a battle to keep drive high and drag low. Going up wind the drive comes from the leading edge of the sail and much of the aerodynamic drag comes from the spars and the trailing surfaces of the sail. The ideal upwind sail profile would be a tall narrow sail on a single tiny spar where the drive is maximized and the drag is minimized. But of course it would be diffucult to keep a proper shape in the sail without a trailing edge and so sails have a leech area. All other things being equal, for a given sail area a Bermuda rig has more leading edge and less spar area than an equal sail area gaff rig and so is more efficient in terms of drive to drag.
But that is only a piece of the puzzle. In order for a sail to be effective going to windward, it is important to control the shape of the sail and the angle of attack of the sail over the entire span of the sail. In some ways, having the combination of throat and peak halyards allow a lot of control of a gaff sail''s shape but in the big picture it is much harder to control depth and placement of camber on a gaff sail. This makes it a little harder to properly flatten a gaff sail when going up wind and still end up with a proper shape.
The other and far more serious problem is twist or angle of attack. On a Bermuda rigged mainsail twist is very easy to control with a high degree of precision using the mainsheet and traveller. On a gaff rig it is pretty much imposible to control twist without either using spencer vangs (think of them as windward and leeward sheets that control the end of the gaff and have to be tacked or jibed), or else negatively altering the sail shape in other ways. Spencer vangs are really not all that effective and are best used on a multimasted rig run from the peak of the gaff aft to the hounds of the mast aft of it. Of course multimasted rigs are inherently poor to windward as well so spencer vangs really do notbuy you much.
So gaff rigs are challenged by lower aspect ratios (or higher heeling if the aspect ratio is kept constant), higher spar drag, poorer section shape control, and poorer angle of attack control. The deck is pretty well stacked against the gaff rig going to windward.