Description of the Nitrider gas spring 081651 – 500 N – Stroke 400 mm
The 081651 Nitrider® gas spring is a heavy-duty compression gas strut manufactured by Associated Spring SPEC UK / Barnes Group UK Ltd (Evesham, UK), produced to the specification of BJ Technologie — the engineering and components division supplying the Beneteau group of production boatbuilders. It is a direct OEM replacement for the original factory-fitted unit on sailing and motor yachts where this reference was specified at build, and a suitable choice for refit or new-build projects requiring the same force, stroke, and mounting dimensions.
The strut belongs to the Nitrider® N10 series from the n-Struts range: a 10 mm rod diameter paired with a 23 mm tube diameter, threaded M8 x 1.25 at each end. The Nitrider® treatment applies a thermochemical nitriding process to the carbon steel rod surface, producing a hard, wear-resistant black outer layer that significantly extends the operational lifespan of the rod seal interface compared to a standard uncoated carbon steel rod. The tube body receives a black e-coat finish per the GSNI specification, completing the uniform, professional black appearance of the assembly and providing a base level of protection against surface corrosion.
With a force of 500 N and a generous stroke of 400 mm, the 081651 is dimensioned for the larger-format mechanisms found on Beneteau-group production yachts: long cockpit locker lids, engine bay access hatches, wide deck panels, or transom storage compartment covers where a shorter-stroke strut would not provide adequate hold-open travel. The body length (L1) is 849 mm and, with both zinc-plated ball sockets fitted, the centre-to-centre length (L2) reaches 909 mm — an important dimension to check against the existing mounting geometry before ordering.
Both ends are equipped with EF-BS006Z zinc-plated steel ball sockets: robust cage-type metal fittings with a 30 mm body length, a 10 mm ball seat, and an M8 x 1.25 threaded shank. The zinc plating provides a practical level of corrosion protection for protected interior or semi-exposed locker environments, and the metal construction gives a higher bearing capacity than a plastic socket equivalent — appropriate for the 500 N force rating of this unit. The sealed cylinder body carries the standard Ressorts SPEC pressure warning label confirming the unit must never be drilled, cut, or exposed to heat.
Distributed in France through Ressorts SPEC, the authorised partner for Associated Spring / Barnes Group components.
Specifications
- Reference: 081651 – Rev B
- Type: Nitrider® compression gas spring
- Force (P1): 500 N
- Stroke: 400 mm
- Body length (L1): 849 mm
- Centre length with end fittings (L2): 909 mm
- Rod diameter (ØR): 10 mm
- Tube diameter (ØT): 23 mm
- Thread: M8 x 1.25
- End fittings (both ends): EF-BS006Z – zinc-plated steel ball socket, Ø10 mm ball, M8 x 1.25, 30 mm body length
- Rod finish: Nitrided black (GSNI specification)
- Body finish: Black e-coat (GSNI specification)
- Original customer: Beneteau (BJ Technologie)
- Manufacturer: Associated Spring SPEC UK / Barnes Group UK Ltd, Evesham
Installation / Maintenance
Installation:
- Clip the EF-BS006Z zinc-plated ball sockets onto the 10 mm ball studs at each mounting point. Align the strut axis with the direction of hatch or panel travel to prevent lateral side-loading on the rod seal and end fittings.
- Before fitting, confirm the 909 mm centre-to-centre length (with fittings) matches the mounting geometry on the vessel — always measure the old strut tip-to-tip before removing it.
- Where the installation geometry permits, orient the strut with the rod end facing downward to preserve the lubrication film on the rod seal and maximise service life.
- The M8 x 1.25 thread and 30 mm socket body provide a robust engagement — ensure both sockets are fully seated on their respective ball studs before applying load.
Maintenance:
- Inspect the zinc-plated ball sockets periodically for wear, excessive play, or surface corrosion — particularly after offshore passages or extended lay-up periods in salt-laden air.
- Apply a light coat of marine-grade grease or silicone lubricant to the ball joints at each annual service to maintain smooth articulation and extend socket life.
- The Nitrider® rod benefits from an occasional wipe-down with a clean cloth lightly moistened with silicone oil to keep the rod surface clean and the seal lubricated.
- The gas strut body is a sealed, pressurised unit — never drill, pierce, cut, or heat it. Replace as a complete assembly when force has noticeably diminished or the rod seal begins to weep oil.
Our review
✔️ Pros :
- 500 N force rating and 400 mm stroke cover a wide range of heavier hatch and access panel applications aboard production sailing and motor yachts.
- Nitrider® rod treatment delivers superior wear resistance and extended service life compared to standard, untreated carbon steel gas springs of the same size class.
- EF-BS006Z zinc-plated steel ball sockets offer a higher bearing capacity than plastic equivalents, appropriate for the 500 N load and 10 mm rod diameter of this unit.
- OEM-grade component from Associated Spring / Barnes Group, the original equipment supplier to the Beneteau group — guaranteed dimensional and force accuracy for direct replacement.
- Uniform black finish (nitrided rod + e-coat body) integrates neatly into any locker or panel cavity.
❌ Cons :
- Nitrider® carbon steel construction — more corrosion-resistant than plain carbon steel but less so than a 316L stainless alternative; best suited to protected interior or semi-sheltered locker environments rather than fully exposed deck applications.
- Zinc-plated ball sockets may show surface corrosion over time in permanently damp or salt-spray environments; consider the stainless steel variant (EF-BS006S) for more aggressive conditions.
- Fixed force of 500 N — verify this matches the load and geometry of your specific hatch or panel before ordering.
- At 909 mm tip-to-tip, this is a long strut: ensure adequate clearance and travel space in the cavity before purchasing.
Conclusion
The 081651 is the correct direct replacement for Beneteau-group yachts and nautical vessels originally fitted with this OEM reference. Its 500 N force, 400 mm stroke, and Nitrider® surface treatment make it a robust and reliable choice for larger hatches and structural panels in protected interior environments. Before ordering, confirm that your mounting geometry matches the 909 mm centre-to-centre length with both end fittings in place, and verify that 500 N is the correct force for your application. If both criteria are met, this strut provides a straightforward, like-for-like replacement that will restore the full functionality of your onboard mechanism. For installations subject to prolonged saltwater exposure, consider upgrading to a stainless steel gas spring and stainless ball sockets for added longevity.
Good to Know
- OEM reference developed for Beneteau (BJ Technologie) — verify fitment against your vessel’s original equipment documentation or measure the existing strut before ordering.
- End fittings: EF-BS006Z – zinc-plated steel ball socket, Ø10 mm ball, M8 x 1.25, 30 mm body length (both ends).
- Total centre-to-centre length with fittings: 909 mm. Body length alone (L1): 849 mm. Always measure tip-to-tip on the old strut before purchasing.
- Nitrider® series: rod is nitrided black and body is e-coated black per GSNI specification — enhanced rod wear resistance vs. standard carbon steel, but not equivalent to stainless steel for aggressive salt environments.
- The cylinder body is a sealed, pressurised unit — never drill, pierce, cut, or heat it.
- Distributed in France by Ressorts SPEC — original manufacturer: Associated Spring SPEC UK / Barnes Group UK Ltd.
- Browse our full range of marine gas springs for other force ratings, stroke lengths, and end fitting options.
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