Using an Anchor Riding Sail
Anchor riding sails can make cruising much more comfortable than it often is. Modern boats have fin keels and rather high topsides. Both combine to encourage swinging at anchor - sometimes over an arc of as much as 50 degrees. This endangers nearby boats and it weakens the anchor’s grip on the bottom by working it from side to side.
The anchor riding sail on this sailboat is circled in red.
An anchor riding sail would seem like an obvious solution for this problem. But many have tried them without success. We believe that this is because they do not rig the sails properly. They think of the sail as a feather on an arrow and, thus, set the sail right down the center of the boat. Unfortunately, the analogy is not a good one since an anchored boat is held at the bow by the anchor line. The center-rigged anchor riding sail does counter a movement to one side, but the force it generates tends to move the stern to the other side of center and the pull of the anchor rode tends to move the bow in the opposite direction. The result is usually a jerky dance on the end of the anchor line that may reduce but does not eliminate swinging. Even with this reduction in swinging, the noise of the anchor riding sail continually filling and backing is enough for most to consider the improvement less than satisfying.
In response to this problem some have suggested a new shape for the anchor riding sail. They create a diamond of fabric that can be pulled forward on its centerline from the backstay at its head to the deck at its tack to create a “V” shaped tail on the boat. This shape does eliminate the backing and filling and the jerky dance is reduced in severity (though not eliminated entirely). Unfortunately, the sail usually interferes with usable cockpit space and it is sometimes awkward to rig (there is often no ready point to attach the tack).
A properly rigged traditional anchor riding sail can eliminate swinging without the disadvantages of the “wedge” described above. We find the size of the sail is actually not critical, but the way it is rigged matters a good deal. It should be hoisted on the backstay. Then sheet the sail forward to the side of the boat so that it is actually sailing the boat to one side of the anchor rode. The boat will only swing so far out as to reach equilibrium with the windage on the topsides. There it will stop and hold its position except for minor moves in response to changes in wind velocity (and tide in some cases). Notice that sheeting to the side clears the sail from the cockpit. And, if the backstay is split, it is perfectly OK to hoist it on the “windward” leg of the backstay.