In purely engineering terms, yacht masts are structural columns designed to resist the compressive forces and bending moments applied by the loads they are subjected to by the rigging and the wind. Spreaders on masthead-rig yachts tend to be angled transversely across the boat, while fractional-rig boats usually have the spreaders swept back at an angle to help support the mast in a longitudinal direction. The other will pass through the ends of the spreaders and terminate at the masthead (masthead rig) or lower down at forestay level (fractional rig) – the cap shrouds.Ī larger mast will require more spreaders spaced up the mast to support it. One set will terminate just below the spreaders – the lowers. Most sloop-rigged yachts will carry two sets of shrouds. The lateral rigging, known as the shrouds, requires a fixed tension to keep the mast upright in the transverse plane. Many yachts will have an adjustable backstay in which the tension can be varied: such adjustments will always affect the tension in the forestay, particularly with a masthead rig. forward and aft), and the lateral rigging supporting the mast across the boat. Whether a yacht has a masthead or fractional rig, they all have common rigging features: a forestay and a backstay to support the mast longitudinally (i.e. A larger version of the Spinlock Rig-Sense for 5 to 8mm diameters has since become available. At the time of going to press, the newly-launched Spinlock Rig-Sense was only available in one size: 2 to 5mm diameter.The SureCheck, which comes in four sizes, from 2 to 10mm.
The Loos, which comes in Standard and Professional models, each in three different shroud diameter ranges, from 2.5 to 10mm.There are currently three makes of rig tension gauge on the UK market designed for yacht rigging: Modern stainless steel shrouds themselves rarely break, but the fittings to the mast or the boat do fail, with consequent failure of the mast.įortunately, there are devices available on the market that enable one to measure the tension and make sure it is set within the right limits. Most mast breakages occur when the mast is overloaded, either by the wind or, more frequently, a collision. Too tight results in extra strain on the various attachment points of the rigging and the shrouds themselves, and can distort the hull as the loads are transmitted through the chainplates.
Too slack, and I know that the sails won’t be working as efficiently as they can: and, worse, the rigging and mast fittings can be subjected to shock loads and fatigue. Getting the correct tension on the shrouds on my various boats over the years has always worried me, writes Alex Bell.
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