Choosing a Backstay Adjuster - Sail Magazine

Choosing a Backstay Adjuster

Whether you’re cruising or racing, an adjustable backstay is a helpful device for changing sail shape and controlling forestay tension for improved upwind and downwind performance. By dialing in the right backstay tension you can increase boatspeed. Regardless of whether you have a masthead or fractional rig, using an adjustable backstay is essential to good sail shape. While
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Whether you’re cruising or racing, an adjustable backstay is a helpful device for changing sail shape and controlling forestay tension for improved upwind and downwind performance. By dialing in the right backstay tension you can increase boatspeed. Regardless of whether you have a masthead or fractional rig, using an adjustable backstay is essential to good sail shape. While an adjustable backstay isn’t as popular on a cruising boat, it is an important tool for easy and comfortable sailing.

Backstay adjusters for cruisers

Most manufacturers of roller-furling gear recommend that you sail with a tight headstay, as this allows the luff foil to rotate more easily and improves the furler’s overall performance; this is particularly important in a gathering breeze when you need to roll a reef into the jib. Whether you have roller-furling or hanked-on headsails, it is useful to be able to control forestay tension easily and quickly. A forestay that sags off to leeward increases the fullness of the headsail as the wind builds; this leads to excessive heeling, which in turn contributes to weather helm. By keeping the forestay taut, you are flattening and depowering the headsail, and the boat sails more upright. While it’s possible to increase headstay tension by simply tightening the headstay or backstay turnbuckle, this is not something you’d want to do under sail.

And when turnbuckles have been tensioned in this fashion, all too often crews forget to loosen them again, leaving the rig over tensioned for extended times. This puts the hull and deck, the mast, and the standing rigging under constant—and unnecessary—stress. On a masthead rig, a backstay adjuster allows you to increase headstay tension when sailing, and to release tension when it’s not needed. It will improve furling-system performance, and allows you to bend the mast aft if you have a fractional rig. This helps flatten the mainsail, often allowing you to postpone reefing, and reduces heeling. Tensioning the backstay, however, won’t increase headstay tension on a typical modern fractional rig with aft-swept spreaders; this is controlled via tension in the cap shrouds, which often induces some pre-bend in the mast.

Choosing an adjuster

Backstay adjusters are either hydraulic or mechanical. Hydraulic adjusters consist of a hydraulic cylinder fitted between the backstay and its chainplate. Integral adjusters have a pump incorporated into the bottom of this cylinder, while other types (typically found only on high-end raceboats) have a remote hydraulic-pump panel connected to the cylinder with a high-pressure hose. When you pump the handle, oil is forced into the hydraulic cylinder, causing the cylinder’s piston to retract, thus increasing backstay tension. A pressure gauge indicates the amount of load on the backstay. The load-multiplying capabilities of a hydraulic system allow you to exert several thousand pounds of pressure on the backstay.

Some mechanical backstay adjusters are essentially precision-machined turnbuckles that employ either a winch handle, built-in handles, or an integral wheel to adjust backstay tension. They have high-strength stainless steel and/or silicon-bronze threads or worm gears designed to be adjusted under load without compromising strength. Some have enclosed gears, which can be fully lubricated without the risk of grease coming off on sails, clothing, or the deck. You might think that simply adding handles to a standard rigging turnbuckle would have the same effect, but the threads on a turnbuckle aren’t designed for repetitive tightening and loosening under load, and so they shouldn’t be used in this manner.

Another form of mechanical backstay adjuster is simple tackle arrangements that use purchase, not hydraulic fluid or precision-machined threads, to tighten the backstay. These systems, which are common on both cruisers and racers, attach to the backstay with a single point of attachment; this single point (usually comprised of high-strength cordage) then multiplies as it travels around and through a series of blocks before terminating at a cam cleat. Tackle systems can either look like a tackle-style boomvang, or they can form a triangle (from the single point of attachment at the masthead down to a block. High-strength cordage attaches at one stern quarter via a padeye, travels up and through the block before turning into a tackle system on the block’s other side, which attaches to a second padeye on the appropriate stern quarter).

Other times, a boat might have twin wire backstays with a car in between the two stays; by pulling down on the car via a tackle system, you can create more load on the backstay. Most of these systems are designed so that the helmsman or mainsheet trimmer can easily adjust the backstay on a racer; most cruising boats have the line termination near the backstay itself, ideally in easy reach of the helmsman. While these systems are fairly simple compared to hydraulic units, they can generate a lot of force if they are properly spec’d for the boat and the rig.

The choice between a hydraulic or a mechanical adjuster is largely one of convenience versus dollars. The hydraulic adjuster is faster and physically easier to use—both for applying backstay pressure and for rapidly bleeding it off—but it is the costlier option. Depending on the model, a mechanical adjuster takes a bit more time and muscle power to tension and release, but it costs less and is mechanically simpler. Whether you choose a hydraulic or mechanical system, installation is usually as simple as comparing the length of the current backstay turnbuckle to the new adjuster and trimming the backstay to fit the new adjuster’s length, using a mechanical-compression terminal such as a StaLok, Norseman, or Hayn.

If the new adjuster is shorter than the existing turnbuckle, add a toggle below the adjuster to make up the additional length. Installing a hydraulic backstay with a remote pump and panel is a complicated job that likely involves multiple hydraulic runs (especially if the pump/panel also controls the boomvang and the outhaul). You are best off to have this installed professionally as your backstay is your rig’s backbone and failure isn’t an option.

mechanical_backstays_diagram

Adjustable backstays for racers

If you’re a racer, you understand the importance of immediately decreasing backstay pressure to power up the main and to help project the tip of your mast forward (which is especially effective on fractionally rigged boats) as soon as you round a windward mark. Because they need to make adjustments rapidly, racers use one of three types of adjustable backstays: hydraulic, a simple or cascading tackle setup, or running backstays.

Hydraulic backstays have a pressure-release valve (usually a knob that you turn counterclockwise to release pressure) or, in some cases, an additional quick-release button that allows you to instantly decrease backstay tension. Because racers are weight conscious, hydraulic backstays are popular aboard boats whose masts are too stiff to be bent by a tackle system (usually this means boats that are 35 feet LOA and up).

While hydraulic backstays have gauges (either on the hydraulic cylinder or on the panel), these are typically hard to read. If you’re racing, a simple, easy-to-read reference point that everyone aboard can see is useful.

Taping a batten to the back of the hydraulic cylinder and marking off one-inch increments, starting at the top of the cylinder and moving upward, gives you an easy visual reference for how much backstay tension is being exerted on the rig. Moreover, it also gives your crew a good sense of the boat’s “gears.” By sailing in a wide variety of winds, you can ascertain how much rig tension your boat likes in certain conditions, allowing you to instantly match rig tension to sail trim.

Small-to-medium-size raceboats (under 35 feet LOA) typically use a tackle system to create purchase; this allows you to create a lot of rig tension by manually pulling on (aboard small boats) or winching in (on medium-size boats) a backstay-tackle line. On boats under about 25 feet LOA, the backstay terminates at a block; a tackle sheet originates from a padeye on one of the stern quarters, runs through the backstay-terminator block, and then runs through a second block that’s situated on the opposite stern quarter (forming a simple triangle shape). From here, the tackle tail is led to a camcleat so that the helmsman or the mainsheet trimmer can quickly add or bleed off backstay tension.

Medium-size raceboats (roughly 25 to 35 feet LOA) typically use a high-purchase tackle system that is orientated in the cockpit so that either the helmsman or the mainsail trimmer can quickly add or release backstay tension. On a raceboat it’s crucial that your backstay can be rapidly adjusted as you approach a leeward or windward mark. Sail your boat in a variety of conditions and determine which “gear” best matches the conditions. Then, using a rope-safe marker, mark your backstay-tackle sheet so that you can quickly shift gears to the optimum setting.

Running backstays are usually found on high-end racers. Instead of a single backstay, there are two independent backstays, port and starboard, that typically attach to the mast at several points before combining into one part that runs to a turning block located on the stern rail and is led to a winch. The reason for using “runners” instead of a permanent backstay is to allow for mainsail with a bigger roach, but the drawback is that you need to have crew diligently working the runners during each tack or gybe. While this setup is effective, it isn’t appropriate for anything except a purebred racer. Many less high-end racers also carry running backs or checkstays in addition to a permanent backstay. These can be used both to mitigate compression loading, and to increase forestay tension on a fractionally rigged boat.

tackle_backstay_adjusters

Whether you’re a racer or a cruiser, an adjustable backstay will improve your sailing experience, enhance performance, and get you where you’re going faster and in more control.

Resources

Hydraulic Adjusters

Sailtec, 920-233-4242

Harken Custom Hydraulics, 262-691-3320

Holmatro, 410-768-9662

Mechanical Adjusters

Harken, 262-691-3320

Wichard, 401-683-5055

C. Sherman Johnson, 860-873-8697

Sparcraft U.S., 704-597-1502

Selden Mast, 843-760-6278

Redundancy for hydraulic backstay adjusters

Hydraulic adjusters are reliable and require minimal maintenance. But like any piece of hardware, there is a potential for failure, and carrying a spare hydraulic adjuster is cost-prohibitive. There are, however, two simple and low-cost backup solutions for hydraulics that begin to leak. The first is to carry an extra bottle or two of hydraulic fluid. Should a hydraulic seal fail, you can add fluid to the reservoir, thus buying time to make a permanent repair. The second option is to have a substantial padeye on deck (just forward of the hydraulic cylinder) and a link (or a toggle) between the backstay and the adjuster that makes it easy to rig a tackle or a “preventer” to a winch to maintain a tight headstay until the hydraulics can be repaired.

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