Join Date: Oct 2009
Location: Cape Cod
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Re: sailing with a partially furled headsail
Most of today's roller furlers that I'm familiar with will reef a headsail. What happens as the sail reefs, if you think about the sail shape it's a little "baggier" in the middle. So when you reef, the shape will be effected. It will be better at the top and bottom, and kinda bagged out in the middle.
Various sailmakers solve this problem different ways by building some bulk into the sail, particularly in the middle part. For example, sewing in a piece of rope that builds bulk in the middle part. This helps a bit; however, most jibs designed this way are only designed to reef a bit, not a ton. So maybe from a 130% (this is the amount of overlap beyond the triangle formed by the forestay and mast) to maybe 100% (no overlap). Beyond that, this fix still tends to bag out in the middle.
So beyond that, it's time to change headsails. Most people I know who cruise, don't do that often. For instance, in some places seasonal winds are stronger, so they put on a smaller sail during the windy season, and put a bigger one on during the less windy season and live with the limitations. Obviously, changing a headsail on a furler is harder than just winding a bit of it up.