Running Backstays and Checkstays: When Are They Necessary?

Running backstays and checkstays are among the most misunderstood elements of a sailboat’s standing rigging. A running backstay is a removable stay that provides aft support to the mast from either the masthead or the point where an inner forestay is attached, while a checkstay performs a similar role lower down, often at spreader height, to control mast bend. They are not universal: many modern cruising boats with inline spreaders and fore-and-aft lowers do not need them, but on some cutter rigs, fractional rigs, and high-performance boats they are essential for keeping the mast in column and the headsail luff tight. This article explains what they are, when they are necessary, and how to use them safely.

Main Explanation

What it is

A running backstay is a removable stay that provides aft support to the mast from either the masthead or the point at which an inner forestay is attached. According to a Cruising World article, it originated as a response to the material limits of wooden masts, which were too weak or too heavy to be made tall; to achieve enough sail area, booms were extended or gaffs added, precluding fixed backstays because the boom and gaff had to swing across the boat. A checkstay is a similar but lower stay, typically attached at or just below the spreader roots, used to control mast bend and support the middle panel of the mast. Both are adjustable: they are set up on the windward side and eased on the leeward side so the boom and mainsail can pass during tacks and gybes. Their core purpose is to counteract the forward pull of a staysail or inner forestay that attaches below the masthead, preventing the mast from bending forward or pumping in a seaway. They are not tied to any specific boat brand, school, or equipment manufacturer; they are a rigging solution dictated by geometry and load paths.

Why it matters

Many sailors inherit boats with runners or checkstays but no clear guidance. Conflicting advice abounds: some say runners are critical, others say they are unnecessary. The stakes are high. If a runner is not set when needed, the mast can invert or break; if set too tight, it can overbend the mast or overload fittings. A YBW forum discussion notes that on some older vessels one runner must be set at all times or risk dismasting, while on other boats they are not critical to safety and can be handled more casually. A separate discussion on a cutter-rigged Dockrell 37 without runners illustrates the uncertainty: the mast had stayed up since 1986, but the owner wondered whether heavy weather with only the staysail and double-reefed main would cause failure. Independent, reliable reference material is scarce, and manufacturer manuals often assume a level of rigging knowledge that many cruisers do not have. The consequences of getting it wrong range from poor sail shape and excessive weather helm to catastrophic rig failure.

How it works

On a masthead rig with inline spreaders and fore-and-aft lowers, the forestay and backstay attach at the masthead, creating a simple triangle. If an inner forestay or cutter stay is added below the masthead, it pulls the mast forward at that point. Without aft support at the same height, the mast will bend forward, potentially causing the middle section to fail or the headstay to sag. Running backstays attach at or near the inner forestay attachment point and lead aft to the deck, providing opposing tension. Checkstays attach lower, often at the spreader roots, and are used to limit forward bend in the lower and middle mast and to tune mainsail shape by controlling mast bend. On fractional rigs, runners are often used to tension the headstay by pulling the masthead aft, while checkstays control the lower section. The windward runner or checkstay is tensioned; the leeward one is eased before a tack or gybe so the boom can pass. Tension is typically applied via block and tackle, a lever, or a hydraulic ram. The exact setup depends on the boat’s rig plan and the designer’s specifications.

How to do it

Consider a coastal passage on a cutter-rigged boat fitted with running backstays. First, identify the inner forestay attachment point relative to the masthead and spreaders. If it is well below the masthead, runners are likely needed. Second, consult the boat’s rigging plan or a certified rigger; do not guess. Third, before setting sail, rig the runners so they can be quickly tensioned and eased. Attach the lazy runner forward to a lower shroud or dedicated padeye to keep it clear of the boom. Fourth, when sailing upwind with the staysail set, tension the windward runner until the inner forestay is straight and the mast is in column. Sight up the mast track to check for forward bend. Fifth, before tacking, ease the old windward runner completely, tack the boat, then set the new windward runner before the staysail is fully loaded. Sixth, in heavy weather, keep the windward runner set at all times when the staysail is drawing. If in doubt, set it before the load comes on. For checkstays, adjust to achieve the desired mast bend for the mainsail: more bend flattens the main, less bend powers it up. Record settings for different wind strengths and sea states.

When not to do it

Do not rely solely on generic online advice or forum posts to decide whether your boat needs runners. If the boat was not designed for them, adding runners can create point loads the mast section cannot handle. Do not use runners as a substitute for a properly tuned standing rig; if the cap shrouds or lowers are loose, runners will not fix the problem. Do not attempt to tune runners or checkstays in strong winds without prior practice; a mistake can cause sudden rig failure. If you are unsure about your rig’s requirements, hire a certified rigger or consult a naval architect. Professional training in heavy weather sailing and rig management is more appropriate than learning by trial and error at sea.

Visual

Imagine a side view of a cutter-rigged sailboat. The mast rises from the deck; a fixed forestay runs from the masthead to the bow. Below it, an inner forestay (cutter stay) attaches to the mast about two-thirds of the way up and runs to the stem. From that same attachment point, a running backstay runs aft and down to a deck padeye near the transom, with a block and tackle. A second, lower checkstay runs from the spreader root to a point further forward on deck. The windward runner is shown taut, the leeward runner is slack and led forward. Arrows indicate the forward pull of the staysail and the opposing aft pull of the runner. Labels identify: masthead, inner forestay attachment, running backstay, checkstay, spreader, deck padeye, and tackle. This diagram helps you see how the loads balance and why the leeward runner must be eased before a tack.

Common Mistakes

Assuming all cutter rigs need running backstays

Consequence: unnecessary complexity, deck clutter, and potential overloading of the mast. Correct approach: check the inner forestay attachment height and mast section. Many modern cutters with inline spreaders and fore-and-aft lowers do not need them, as the Dockrell 37 example shows.

Forgetting to ease the leeward runner before tacking or gybing

Consequence: the boom or mainsail can foul the runner, causing chafe, a jammed tack, or a broken fitting. Correct approach: make “ease old runner, tack, set new runner” a practiced sequence with clear communication.

Overtensioning checkstays to flatten the main

Consequence: excessive mast bend can invert the middle section, damage the mast track, or overload the spreader roots. Correct approach: adjust checkstays in small increments, sight the mast, and follow designer limits.

Using runners as a permanent backstay

Consequence: if both runners are set tight, the boom cannot swing and the rig is over-constrained; if one is left set on the wrong side, the mast can be pulled sideways. Correct approach: runners are dynamic; only the windward one should be tensioned, and the leeward one eased.

Ignoring the boat’s rigging plan and relying on forum advice

Consequence: a rigging setup that works on one boat may be dangerous on another. Correct approach: obtain the manufacturer’s rigging guide or have a certified rigger inspect and document the correct runner and checkstay settings.

Not inspecting runner terminals and tackles regularly

Consequence: a failed terminal or worn tackle under load can cause sudden loss of mast support. Correct approach: include runners and checkstays in annual rigging inspections, replacing worn pins, shackles, and line.

Safety Note

Running backstays and checkstays are load-bearing rigging components; they must be treated with the same respect as standing rigging. Always cross-check your boat’s rigging requirements with the designer’s specifications or a certified rigger before making changes. Never use a phone or tablet as your only source of rigging information while under way; keep a printed rigging plan and a basic rigging guide on board. When setting or easing runners, stand clear of the loaded line and tackle; a parted runner under load can whip violently. Ensure all crew know the tacking sequence and can identify which runner is loaded. In heavy weather, set the windward runner before the staysail is fully loaded, and ease it only after the load is off. Follow COLREGS and local maritime regulations regarding vessel safety; a dismasting at sea is a serious emergency that can endanger the crew and require outside assistance. Take a certified safety and seamanship course that includes rigging management, and practice runner handling in moderate conditions before relying on it offshore.