Know-How

Higher and Faster

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Recently, a sailmaker called to inquire about upgrading the backstay system on his client’s mid-1980s 34-foot masthead-rigged sloop. The client was buying a slightly larger headsail that could cover a broader spectrum of wind ranges and thought that the standard backstay and turnbuckle just weren’t up to the task. The working range of the turnbuckle was 2 to 3 inches of length, and the time and hassle of dealing with wrenches, pliers, cotter pins, and tape each time an adjustment was needed was so daunting the client hadn’t touched it in years. The boatyard tuned the rig each spring, and that was how she left it. She knew enough from Wednesday-night club racing on friends’ boats that changing tension on the backstay was important, but was a little leery of adjusting her own rig. After spending time with the sailmaker and discussing the benefits of an adjustable backstay system, she was ready to look over the options.

Modern sails are cut, sewn, glued, and taped into shapes that are light-years ahead of what was available 25 years ago. The laminates and shapes, along with the myriad computer programs and the ability to cut panels within fractions of inches, have made modern sails very adaptable to wind speed and direction. Taking a little care to get halyard tension correct and sheet angle and lead right can result in pointing higher and going faster. However, ignoring these and other adjustments will prevent you from enjoying all this wonderful technology.

Often overlooked in this equation is headstay tension, the first step in proper sail trim. If too much tension is applied when sailing off the wind in light and fluky conditions, the sail remains flat and can’t generate lift. If the tension is backed off, the headstay softens and a graceful arc allows the headsail to power up. Conversely, when you turn the outer harbor buoy and come on the wind to head back to the mooring, that soft arc prevents you from making headway and driving to weather; more tension is needed.

A fractional rig, where the headstay does not terminate at the masthead, has almost the same parameters as the masthead rig, even though the geometry is slightly different. For example, when backstay tension is applied to a fractional 3/4 rig, the headstay will get only about 50 percent of the tension that would be applied to a masthead rig. This is why runners were commonly used on many early fractional-rig designs; they pulled the mast aft at the headstay attachment point. More-recent fractional-rig designs can handle this problem without runners because the headstays on most fractional rigs intersect the mast much closer to the masthead than earlier designs. Today’s masts are engineered so they can transfer headstay tension with minimal bend. In short, a contemporary fractional-rig design, even one that has swept-back spreaders, functions almost like a masthead rig. However, knowing how much tension to apply and the length of throw needed for a backstay adjuster is as important with a fractional rig as it is with a masthead rig.

Headsail furlers further muddy the waters as they require proper tension when reefing or furling the headsail; the tube or extrusion has to spin in something of a straight line when the control line is turning the furling drum. When the headstay is properly tensioned, furling requires less effort and puts less wear and tear on the headstay system’s connectors and joints. The tension required by the headstay and furling system to properly set and retrieve the sail in 23 knots of breeze will change if the wind drops to 8 knots. Until higher-tech sail materials and control lines came into use, sailors could strike a balance between the two tension points, but modern furlers and sails make backstay adjustment a necessity.

There are several adjustment systems, and your mast type—masthead, fractional, single-spreader, double-spreader, and so forth—will affect the amount of adjustment and force that is required and the best system for the task. The transom area and backstay end points will also influence your choice.

Cascade block-and-fall systems can be the simplest type of backstay adjuster and have become the choice for a fair number of one-design classes where speed of operation and light weight are priorities. Depending on the amount of power needed, a series of blocks is set up to achieve a starting purchase and increased by adding additional splits. For example, if a starting point of 6 to 1 is run to a 2 to 1 and then to an additional 2 to 1, the final power is 6x2x2, or 24 to 1. Always select hardware with the lowest possible friction. And since the cascade is also the backstay, all blocks and mounts must be able to withstand the loads anticipated in a shock-loading situation, such as hitting a wave at speed or having the spinnaker fill quickly in a puff. Sometimes a safety wire is set up in case of block failure. It is astonishing how much loading can be applied by systems sometimes approaching 100 to 1. Although the upper-echelon systems and components can be expensive and even a little intimidating to set up and operate, most of these systems are reasonably priced and have the added benefit of a long throw.

Split-backstay systems were popular in the 1970s and ’80s. A single backstay from the masthead would terminate at a plate some distance off the deck, and two legs would then split off and run down to either side of the transom. Because turnbuckles on each leg lack power and throw, mounting interconnected blocks over each leg and connecting them to a block-and-tackle will pull the legs together and apply tension. Increasing mechanical advantage involves increasing the block purchase or moving the split point higher up. Here again low-friction systems are a must. Above a certain wire size, a point of diminishing returns is reached.

Contemporary designs have split, or twin, backstays for a different reason—transom access. Today’s cruising-boat transom is a swimming, diving, and launching ramp with high traffic. That causes a certain amount of complexity. Up to certain sizes, a combination of splits and cascades has worked. As boat size increases, hydraulics have become an attractive alternative.

Hydraulic cylinders offer power, speed, and low maintenance. When properly sized and with maximum pressure preset at the factory, their reliability is very high. Depending on use and weather exposure, 10 or more years between replacing seals and fluid is routine. Once the exclusive tool of the high-end racer, hydraulic cylinders are now standard equipment on many cruising boats. There are stand-alone cylinders, called integrals, with the pump and handle built into the cylinder. Simple and light, with reasonable cost, these integral units are by far the most popular hydraulic system. In larger boats with wire or rod larger than 5/16(/8mm or -12, it’s the only way to get the power needed to tension the headstay.

A panel system is another hydraulic option and is used on larger boats and for racing applications. A panel pump and a reservoir are mounted in a convenient spot in the cockpit, and cylinders are placed in line at the base of the backstay, or backstays in a split-stay setup. This makes sense when the backstay is hard or dangerous to access and allows for the addition of other cylinders elsewhere, such as the vang or headstay.

Mechanical backstay adjusters are another option. These adjusters are available with wheels, handles, and cranks; they either use a simple screw system or turn a pinion gear against a worm gear. Some of them ratchet and others lock, but they all come at a relatively modest cost somewhere between cascades and hydraulics. Sized according to wire size, they can handle small to medium applications, but with limited power output they are not a good choice for a large boat. Early versions produced in the ’70s and ’80s had gear-stripping failures, but these have been corrected. When they are correctly matched to the rig, today’s units are very effective.

After I had explained all these options to the client, she decided to install an integral hydraulic adjuster on the backstay. With some final rig tuning and adjustment, along with a bit of advice and a new sail, she went off on a two-week vacation. Her response to the upgrades was immediate and enthusiastic. Going upwind, the boat had never sailed as high or as fast. The furler required much less effort, and sailing in a squall with a 30 percent reef proved very effective. The balance of the boat improved on all points of sail, requiring much less steering effort from her and less power draw from the autopilot.

Sailing over two days with another boat that had previously been much faster, she was happy to say that the tortoise had become the hare. But (a frequent comment) why hadn’t she done this sooner? Adjusting the backstay to fit the conditions was not only fun, she said, it was easy to do and very effective. A backstay is a sail-control system that really works.


Kevin Montgomery has been splicing halyards, dock lines, and anchor packages since he was 12 years old. A veteran ocean racer and delivery captain, he is a principal in North East Rigging Systems, www.nerigging.com.

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