Adjusting the standing rig for tension and straightness
How tight should a sailboat’s standing rigging be? It’s a question that often engages the mind of amateur sailors. The old rule of thumb was that when you’re on a beam reach under normal working sail in a moderate breeze, the shrouds on the leeward side should feel slightly slack, but not look slack to the casual observer.But that’s a little too imprecise for most people, especially because it’s possible to measure wire tension with a simple gauge you can buy at a marine store, such as the Loos gauge. By pretensioning the rig, you avoid the sudden shock loads that wind gusts will impose on a floppy rig. But too much permanent tension can cause hogging of the sheerline and drive the mast downward with enough force to distort the cabintop or damage the keel.The mast should remain perfectly straight under sail unless it’s a fractional rig purposely designed to bend or a freestanding mast with no fixed rigging.Follow these steps to tension the rig:
- 1.Give the upper shrouds and backstay a tension of approximately 10 percent of the boat’s displacement. (You will induce a slightly higher tension in the forestay—which is good—because of the narrower angle it makes with the mast.)
- 2.Tighten the forward lower shrouds (or babystay) so that the mast bows forward slightly but noticeably at the spreaders.
- 3.Tighten the aft lower shrouds to straighten the mast again.
- 4.Sail for a few hours in moderate winds, allowing the rig to adjust itself.
- 5.While still in a moderate breeze, straighten the mast from side to side by adjusting the appropriate shrouds, if necessary. Unscrew the turnbuckles on one side a few turns before taking up the turnbuckles on the other side the same number of turns. It usually pays to tackle the lowers first, making sure the mast is middled and straight as far as the spreaders. Then adjust the cap shrouds to straighten things out from the spreaders upward.
