Standing Rigging 27

4 – Standing Rigging 27 Section 4 Standing Rigging Chain Plate. Metal strap on a sailboat, usually secured Quarter. After part of a boat’s side, e.g., port quarter. Also, to hull structure or bulkhead, to which a shroud or stay direction 45 degrees abaft the beam. is attached. Shroud. Standing rigging that supports a mast laterally. Leeward (Loo’ard). Direction away from the wind, downwind. Stays. Standing rigging that supports a mast fore and aft. 1 The mast on a sailboat must either be strong enough to stand by itself under a full press of sail, or it must be supported by standing rigging. This section discusses shrouds, stays, and spreaders: the fundamental compo‑ nents of standing rigging, Figure 4–1. 2 A simple standing rigging, found on sailing dinghies, consists of two shrouds and a jibstay, Figure 4‑2. The ends of these supports typically have swaged terminals Jibstay Shrouds with an eye at the upper end and a turnbuckle stem at the Backstay Jibstay Upper Boom Shroud Crutch Lower Shrouds Figure 4–2 Simple Standing Rigging lower end. Swaging is a method of permanently attach‑ ing terminals to wire rope by deforming a steel sleeve to clamp it to a wire securely. The shrouds and stays are typically attached at the upper end to tangs that are a part of the mast, Figure 4‑3. The lower ends of the jibstay and shrouds connect to the stemhead fitting and shroud chain plates, respectively, through turnbuckles. Turnbuckles permit easy and precise adjustment of standing rigging, Figure 4–1 Standing Rigging Sail 28 4 – Standing Rigging Mast Ta ng Through Bolts Clevis Pin Swaged Fitting Shroud or Stay Cotter Pin Backstay Jibstay Figure 4–3 Shroud and Tang Assembly Shroud or Stay Swaged Fitting Right Hand Thread Tu rnbuckle Barrel Cotter Pins Left Hand Thread Marine Fork Clevis Pin Figure 4–5 Fractional Rig Sloop provide a better sail shape, is possible with a fractional Cotter Pin rig. Spreaders Deck 4 The angle formed between a mast and the supporting Bolt to Hull shrouds is an important factor in determining the com‑ Chainplate pression load on the mast. Compression is the downward force on the mast imposed by tension on the shrouds Figure 4–4 Turnbuckle and Chainplate brought on by the force of the wind. Figure 4‑4. Standing rigging is generally made of stain‑ less steel wire rope, but rod rigging is sometimes used 5 Shrouds that run directly from the top of the mast to to reduce stretch. Reduced stretch is desirable in rigging the chain plates form a small angle at the masthead. in order to maintain it in proper adjustment. Galvanized This small angle increases the compressive force on the iron wire was also used for rigging in the past. mast and could buckle it. To reduce the stresses, small horizontal spars called spreaders are placed part way down the mast, Figure 4‑6. Spreaders increase the angle Masthead/Fractional Rigs between the shrouds and the mast at the mast tang and 3 Boats may have masthead rigs or fractional rigs. On thus reduce compression loads on the mast substantially. masthead‑rig boats, the jibstay and upper shrouds are On tall masts, two or three sets of spreaders may be attached at the very top of the mast. The advantage of the used. masthead rig is that it permits the use of taller jibs with longer luffs and the rigging supports the mast throughout its length. On boats with fractional rigs, the jibstay and, Shrouds usually, the shrouds are attached below the top of the 6 Upper shrouds are connected at the deck level through mast, at about three‑quarters of the height of the mast, turnbuckles to chain plates, which may be bolted to Figure 4‑5. Bending the mast by adjusting the stay, to bulkheads or embedded in the hull abeam the mast. Lower shrouds run from tangs connected to the mast Sail 4 – Standing Rigging 29 Truck the leeward running backstay is led forward out of the way. Headstay Backstay 9 Many racing boats and some cruising boats have adjust‑ (Jib Stay) able permanent backstays. A system of blocks, turnbuck‑ les, or hydraulic pumps can be used for the adjustment. By applying extra tension to the backstay when going to windward, the top of the mast can be pulled aft to Upper keep tension on the headstay, thus improving windward Shrouds performance. On fractional rigs, tensioning the backstay also bends the mast and thus shapes the mainsail for im‑ Spreaders proved windward performance. Off the wind, the extra tension is released and the mast stands up straighter. This allows a better sail shape for the different wind angle. Maintenance 10 Regular inspection and maintenance of standing rigging is required and should not be neglected (as it often is). Inspect all elements and lubricate all fittings annually. Lower Examine all swages for cracks and inspect the wire for Shrouds broken strands—called “meat hooks” because of what they do to bare hands. Coat clevis pins and turnbuckle Figure 4–6 Staying the Mast threads with a heavy waterproof lubricant. Cracked rig‑ ging swages are often discovered by marine surveyors below the spreaders (or from slots in the mast) to deck‑ during pre‑purchase and insurance surveys. In warm level turnbuckles and chain plates forward and abaft the weather climates, replacement of standing rigging as mast. On some rigs having aft swept spreaders, upper and often as every five years may be necessary. lower shrouds may be attached to the same chain plate. Chainplates which are mounted inboard of the gunwale 11 Since swaging requires special tools that are not always allow a closer sheeting angle when closehauled. available, some owners prefer to use Norseman® or Sta‑ Lok® terminals, which are owner‑installed by screwing together the two parts of the terminal around the special Backstay interior cone or wedge. Cruising sailors frequently carry 7 The forces that tend to bend the mast forward may be resisted by a backstay. This stay runs from the masthead stainless wire and rigging terminals that they can install to a secure fitting or fittings on or near the transom, Fig‑ themselves, should the need arise. ure 4‑5. On most dinghies the shrouds connect to chain plates slightly abaft the mast at the deck and a backstay is not required. The Bergstrom & Ridder Rig 12 The B&R rig takes the swept back spreader a step further. 8 Some masts require special support because of additional The angle on this rig is a massive 30 degrees. The idea loads. An example is the load from the inner forestay on behind the rig was to contain rigging loads as much as a cutter‑type sailboat. A pair of running backstays run possible within the mast structure itself and avoid loading from the mast, at the height where the inner forestay the deck and hull. This allowed builders to make lighter connects, to the deck at the boat’s quarters. These run‑ boats and not have to reinforce deck and hull structures ning backstays can interfere with the trimming of the for strength, reducing construction costs. This also al‑ mainsail on some points of sail. Therefore, they are lows builders to use a lighter mast section, reducing rigged through a system of blocks on the deck so they the cost of the rig. More recent developments of the rig can be moved forward out of the way when not in use. includes reinforcements by incorporating rigid struts When a boat with running backstays is sailing off the between chainplate and the gooseneck. The purpose wind, the windward running backstay is set up, while being to distribute the compression loads on the mast Sail 30 4 – Standing Rigging reducing the amount of reinforcement the deck needs to take the download pressure of the mast, Figure 4–7. 13 The big advantage of this rig is that it allows more roach in the leech of the mainsail increasing sail area for better downwind performance. The swept back spreaders also give a great amount of fore and aft support to the mast, eliminating the need for a backstay. 14 The downside to having spreaders swept back in excess of 25 degrees is that it creates too narrow of a shroud base, which means the mast gets less lateral support and the shrouds have to pull harder to keep the mast standing. This creates enormous load pressures. Another major disadvantage to the swept back spreaders is when running, they restrict how far the boom can be let out. Three problems with this situation; main chafe on the spreaders, not being able to depower the main quickly in heavy winds and you round up, and you are forced to oversheet the main and gybe downwind because you can’t set the boat up on a dead run. Summary 15 The simplest standing rigging, found on sailing dinghies, consists of two shrouds and a jibstay. On masthead‑rig boats, the upper shrouds and jibstay are attached at the very top of the mast. The advantage of the masthead rig is that it permits the use of taller jibs (with long luffs) and the rigging supports the mast throughout its length. On boats with fractional rigs, the jibstay and, usually, the shrouds are attached well below the top of the mast, at about three‑quarters up the length of the mast. Mast bend is more easily controlled with a fractional rig. Spreaders increase the angle between the shrouds and the mast at the mast tangs and thus reduce compression loads on the mast substantially.

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