Safety Harnesses and Tethers Compared: Spinlock, Wichard and Kong

This is an independent, objective comparison — no partner in this category. Built from makers' published specifications and standards, not a hands-on test; figures are attributed to their sources.

Every certified tether clears the same direct-axis shock test — a 100 kg mass dropped two metres. The engineering that separates these three brands lives entirely in the failure modes that test doesn't cover: off-axis gate loading, nose-hook roll-out, the metallurgy of the hook body, and whether the chest attachment can be released under load. For the fundamentals, see tethers and jackstays explained.

At a glance

The three, and where each actually leads

• Spinlock owns the system: the ISO 12401 deck harness is built into the ISO 12402-3 Deckvest, sharing one soft-loop sternum attachment, and the HRS lever makes that attachment load-releasable — the offshore differentiator. Its Performance safety lines use 16 mm dry-coated webbing and its own cast-alloy wide-gate double-action hooks.
• Wichard owns the metallurgy: forged 316L stainless hooks with the Torsion Gate mechanism, published at 1,200 kg working / 2,800 kg breaking, EN 362 rated. A steel hook body is the one that resists deforming when nose-hooked across a jackstay.
• Kong owns the off-axis case: the Tango is the only popular locking tether hook derived from via-ferrata climbing practice and certified to World Sailing's ISO 12401, and it is the one independent testing found survives eccentric loading where sailing-pattern clips fail.

The comparison

Hook gate architecture — where lives are lost

Direct-axis strength is a solved problem. ISO 12401 proves it by dropping a 100 kg mass 2 m onto the assembled tether; anything on this list passes. The Clipper and other clip-in fatalities did not fail on the direct axis — they failed off-axis, and this is the single most important engineering axis in the category.

The mechanism is roll-out. A snap hook loaded across the gate, or whose nose has hooked onto webbing or a jackstay eye rather than seating in the throat, can walk the gate open and release. Practical Sailor's bench work on the long-lived Gibb-pattern hook (the basis of older Spinlock/Plastimo race clips) is unambiguous: the gate breaches under less than 30 lb of cross-load, the nose then hooks the webbing and the spine progressively straightens, letting go entirely at roughly 350 lb — 5–7% of the hook's rated direct-axis strength. That is the design to avoid, whatever the badge on it.

The three brands answer this differently:

• Wichard's double-action hook is forged 316L stainless. In the same testing the steel body does not straighten under off-axis load; instead it holds until the nose cuts through the webbing at around 900 lb and tears out near 1,200 lb. That is an order of magnitude better than the Gibb pattern, and it is a direct consequence of forged steel section over cast aluminium.
• Kong's Tango comes from via-ferrata climbing, a discipline where a via-ferrata fall factor can exceed 2 and a gate failure is fatal. It carries an auto-locking double-action gate and is the only popular sailing hook whose body is engineered to the climbing off-axis regime; independent testing put its nose-hook strength around 1,160 lb and rated it as the one common locking clip that genuinely withstands eccentric loads.
• Spinlock's current Performance hooks are cast aluminium with a wide-opening double-action gate — a real improvement on the plain Gibb clip and easy to work one-handed, but an alloy body does not match forged steel for resisting deformation when nose-hooked. Spinlock's stronger safety argument is at the harness end (below), not the hook body.

For a Melges 40, where crew clip onto taut jackstays and pad-eyes and move fast in a seaway, the off-axis case is the one that occurs. A forged (Wichard) or via-ferrata-derived (Kong) hook is the defensible choice; the mitigations — taut hardware-free jacklines, reinforced pad-eyes, never clipping raw webbing — matter regardless.

Standards: ISO 12401 is necessary but not sufficient

ISO 12401 governs the deck harness and safety line; ISO 12402-3 governs the lifejacket it may be built into. World Sailing's OSR mandate the ISO 12401 tether, and the shock test (100 kg / 2 m) is genuinely demanding on the webbing and stitching. The gap is that ISO 12401 has no off-axis test and no gate-open strength test — precisely the loads that cause roll-out.

The climbing world already solved this. EN 12275 / UIAA-121 Type K (Klettersteig / via ferrata) requires 25 kN major axis, 7 kN minor axis, 8 kN with the gate open, plus a unique 8 kN over-an-edge test and a mandatory auto-locking gate with a ≥21 mm opening. That is the exact battery of off-axis cases sailing certification omits, which is the technical reason the Kong Tango's Type K body is meaningful and not marketing. Wichard's hook is certified to EN 362 (industrial fall-arrest connectors), a different but also off-axis-aware regime. The practical reading: treat ISO 12401 as the floor, and prefer a hook that additionally answers a climbing or fall-arrest connector standard.

Chest attachment and load-release — the drowning case

The failure ISO 12401's strength tests cannot address is being held under the water — pinned beneath an inverted hull, or dragged alongside at speed with the tether taut. A fixed soft loop keeps you attached; here that is the problem, not the solution. The current ISO 12401 revision requires the tether to be releasable, which most makers satisfy by making the webbing cuttable — but a knife is a poor tool one-handed, underwater, under load.

• Spinlock's HRS (Harness Release System) is the strongest answer: a lever immediately behind the soft-loop sternum attachment releases the tether under load, freeing the wearer without a knife. On a Deckvest this sits exactly where the hand already is, and it is the single feature that most distinguishes the Spinlock system for offshore Grand Prix use.
• Wichard offers the Proline'R — a chest-end mechanism that releases the tether under load — as the equivalent capability on the hardware side, alongside conventional snap-shackle and fixed terminations.
• Kong terminates the chest end in a stainless snap shackle with a welded O-ring, which can be released, though a snap shackle under high load and awash is harder to trip than a purpose-built lever.

For an offshore crew, load-releasability is not a luxury feature; it is the counter to the exact scenario a tether creates.

Body metallurgy and corrosion

Hook bodies split into two camps. Forged 316L stainless (Wichard) is denser, stronger in section and effectively immune to the crevice and pitting corrosion that afflicts lesser stainless — the reason it holds its shape under off-axis load and after years in a wet locker. Cast aluminium alloy (Kong Tango, Spinlock Performance) is markedly lighter and, when anodised and correctly alloyed, corrosion-stable for marine service; the Tango proves alloy can still meet the Type K off-axis regime through section and geometry rather than material strength alone. The trade is honest: steel for ultimate off-axis integrity and longevity, alloy for weight on the clip you handle a hundred times a watch. Neither is "better" absolutely; a bow team chasing grams and a delivery skipper chasing service life will rationally choose differently.

Webbing, elastic and mass

The tether body is the component that actually wears out, and it is where Spinlock has done the most visible engineering. Its 16 mm dry-coated webbing is quoted at 28% lighter than standard 25 mm line and treated to shed water rather than soak it — a tether that stays light and doesn't freeze stiff. Published Performance line masses run from 226 g (single 1 m) to 565 g (three-clip 2 m), with elasticated versions around 245–367 g; the elastic keeps the line off the deck to reduce snag and trip without adding meaningful shock absorption (the webbing and stitching carry the arrest). Wichard's forged hooks add mass at the ends; Kong sits between. On a Melges 40 the elasticated, dry-coated, twin-length format is the sensible default: two hooks of different lengths let you clip the second before releasing the first and never break the chain.

Overload indicators and retirement

All three build in a tell-tale, and the thresholds differ. Spinlock's flag trips at roughly 500 kg; Kong's stress flag exposes at about 900 lb (~408 kg); Wichard integrates an equivalent indicator. The number is deliberately well below breaking strength: it marks a survived shock load that has consumed the webbing's margin. Once tripped, the tether is scrap — no exceptions, no inspection reprieve. This is the one place where "buy on the badge" is genuinely irrelevant: the indicator, not the brand, tells you the tether is done, and any tether that has arrested a real fall retires regardless of whether the flag showed.

Ease of operation under load

You clip and unclip constantly, one-handed, in the dark, cold, on a moving foredeck — and the design tension is real: easy to open deliberately, impossible to open by accident. Spinlock's wide-gate cast hook is the easiest to find and thumb open by feel. Kong's auto-locking Tango gate is climbing-bred for confident one-handed use with a positive lock. Wichard's Torsion Gate is deliberate — squeeze the rear lever and the hook together — which is the point: it cannot be flicked open by a snag, at the cost of being marginally slower to operate. The hook a crew can work confidently by feel is the one they will actually use correctly, so this is worth handling in person before committing a whole boat.

Our picks by role

• Off-axis hook integrity — Kong Tango for its via-ferrata Type K body (the only ISO 12401 hook engineered to the climbing off-axis regime), or Wichard for forged-steel section (~900 lb before it will even cut webbing). Either defeats the Gibb-pattern roll-out that lets go at ~350 lb.
• The harness itself, offshore — Spinlock Deckvest, for the integrated ISO 12401/12402-3 load path and the HRS load-releasable attachment — the one feature that answers the drowning-while-attached case.
• Longevity and worst-case metallurgy — Wichard forged 316L, for a hook that holds its shape off-axis and survives years of salt.

The takeaway

The badge matters far less than the failure mode. Buy a hook that survives off-axis and gate-open loading — a forged Wichard or a via-ferrata Kong Tango — not merely the direct-axis shock test every certified clip passes. Fit a load-releasable chest attachment (Spinlock HRS, Wichard Proline'R) for offshore. Keep the webbing in date, and retire any tether the moment its overload indicator trips (~500 kg Spinlock, ~900 lb Kong) or after any real arrest. Integration into the lifejacket is why the harness actually gets worn, and it belongs on the safety audit.

Our pick: no single winner — Kong Tango or Wichard for the hook that won't roll out off-axis (Type K body / forged 316L respectively), Spinlock Deckvest for the integrated harness with a load-releasable HRS attachment. On a Melges 40 the strongest combination is a via-ferrata or forged hook on the boat end and a Spinlock HRS soft loop at the chest — engineered for the off-axis and drowning cases the direct-axis shock test never touches.