Rigid vangs are an elegant answer to sail shaping, and with few moving parts, excellent longevity and user friendliness, it's no surprise that they've become a favored piece of after-market hardware.
The conventional boom vang may be the unsung hero of mainsail shape, but the rigid vang is an even better deal. Like the Windex, the rigid vang is a simple but elegant invention that provides lots of value and has no wires to connect, amps to draw or hydraulic system to maintain.
The rigid vang behaves like an accelerator, allowing a crew to boost off-the-wind performance.Like the conventional boom vang, the rigid vang's major role is to control the boom's vertical angle, influencing leech twist and providing important sail shaping capability. In essence, it behaves like an accelerator, allowing a crew to power up–boosting more off-the-wind performance.
On-the-wind, the mainsheet/traveler impacts both vertical and horizontal boom angle, controlling the sail's angle of attack, leech shape and even the draft or fullness of the sail. But this doesn't mean that the vang should always play a dormant role on weather legs. One-design sailors first learned the art of vang sheeting, a heavy air technique in which vang tension flattens the sail through mast bend, while at the same time removing twist from the leech.
With this trimming technique, the main sheet is used only to control the horizontal boom angle. Power up and spilling breeze is accomplished with the vang. In addition, proactive vang use can also help tame the roll, lessen seam chafe and work miracles to help keep the top trailing edge flying. The rigid vang can also un-weight the boom in light air, opening up the leech of the sail.
While many new boats come with a rigid vang as standard equipment, it is possible to retrofit an older boat, so long as the system is designed carefully to shoulder all the loads delivered by wind and sea and the installation is carried out properly.
CARRYING THE LOAD
For years the Hall brothers (Ben and Eric) owned the show with their Hallspar Quickvang, and their latest iteration continues to be a major player in the fleet. Today's Quickvang is half the weight of the early unit. A gas filled cylinder has replaced the familiar spring technology. In essence, the device works as a boom support, replacing the toping lift, when the mainsail is dropped, and functions as a conventional vang when the sail is set.
This "dual purpose" does, however, come with a few inherent problems. The most significant is the importance of making sure that the goose neck fitting and mast and boom attachment lugs are strong enough to handle the increased loads.
In essence, the boom acts like a lever being lifted by the energy derived from the mainsail, and the vang attachment point becomes a fulcrum located even closer to the gooseneck fitting than a mid boom mainsheet. As with all levers, the end closest to the fulcrum sees an increase in force directly proportional to the ratio of segment lengths.
Most manufacturers want a 30 to 45 degree vang-to-boom angle, but on long booms the segment ratio can still be quite high, requiring a larger vang and stouter mast and boom support points. When the sail is furled, the rigid vang becomes a compression strut supporting the weight of the boom. None of these units should be used to offset the sheet loads associated with a doused and covered mainsail. Before leaving the boat, a main halyard needs to be set up at the end of the boom and tensioned to lessen the compression load on the rigid vang, decreasing the chance of "spring memory" problems or damage to the seals in a gas cylinder.
Like the conventional boom vang, the rigid vang's major role is to control the boom's vertical angle.Gooseneck, mast and boom attachment point failures are usually linked to poorly engineered and installed reinforcements. Anchoring hardware must spread the sailing loads associated with vang use. This includes both wind- and seaway-induced forces. It is vital to keep the stress and strain within the limits of the hardware's safe working load rating, and important to consider the duty cycle that the vang will see.
Those who are ocean racing on an around-the-clock scheduled need a heavier unit than those club racing on occasional weekends. Metal fatigue caused by cyclic loading is the real enemy, and the more hours the gear is in use and the more oceanic the conditions encountered, the more logical it is to opt for the next size larger vang and fittings, which will be more rugged than those associated with inshore use.
Many booms come with welded lugs for vang attachment and as long as these anchoring points effectively spread vang loads over a sufficient area, it's a good mounting approach. Welded lugs eliminate the need to drill holes in the boom or spar, and if a topping plate or internal doubler has been added, a potential stress riser is eliminated.
Many slotted spars come with sliding lugs meant for vang and sheet support. This may be adequate in some cases and not in others – it all depends upon the forces involved and the ruggedness of the sliding lugs themselves. More often than not, additional mounting hardware is needed and most rigid vang manufactures offer specific custom fittings to mount their products. Thin wall section masts and booms need larger surface area support in order to more effectively spread the compression and tension associated with vang usage. Those with carbon spars should consult with the manufacturer for detailed hardware mounting guidelines.
TYPES OF VANG
The current trend in rigid boom vangs has gone in three directions. The conventional alloy tube design with a stainless steel spring and multi-part tackle arrangement is still quite popular and often represents an effective cross between reliability and cost. Products like Forespar's Yachtrod, Garhauer's rigid vang and the original Hall Quickvang are examples of this reliable technology.
