🔍 Dyneema® SK99: the high modulus fiber for demanding textile assemblies

Dyneema® SK99 is the highest-performance fibre in the HMPE (High Modulus Polyethylene) family.
If you need a lightweight, ultra-strong and near-zero-stretch line, SK99 is the benchmark.

This guide explains why this fibre is used in modern textile rigging — loops, lashings, standing rigging, bobstay — and how it improves your boat’s performance and reliability.

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✅ 1. What Makes Dyneema® SK99 Stand Out

• +20% strength compared to SK78

SK99 offers significantly higher specific strength.
→ Ideal for securing a critical load point (bobstay, textile stay, high-load anchor points).

• Extremely low stretch

Typical working elongation: 0.5–0.9% at ≈20% of breaking load.
→ Your settings remain stable, predictable and precise.

• Very low weight

Density: 0.97 → the fibre floats.
→ Less weight aloft or forward = a more responsive boat.

• Excellent resistance to UV, salt and chemical exposure

→ SK99 maintains its performance even in harsh marine conditions.

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⚙️ 2. How an SK99 Hollow Braid Is Constructed

✔️ 12-strand hollow braid

• Very supple

• Fast, clean splicing

• Low twist under load

✔️ Heat-setting (pre-stretching)

→ Improves dimensional stability and reduces the bedding-in phase.

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🧭 3. What Dyneema® SK99 Is Used For Onboard

🔗 Loops and lashings

To fix a point, transfer load or replace metal fittings.

⚓ Standing rigging (textile)

Shrouds, stays, depending on dimensioning.
→ Very low stretch = stable rig settings.

🎯 Load-bearing points

Bobstay, deflection points, fixed anchor points.
→ High strength with minimal diameter.

🔩 Soft shackles

Strong, flexible and secure.

🧰 High-performance anchors

Textile padeyes, modern attachment points.

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📊 4. Typical Performance Data

SK99 GorillaRopes 12-strand hollow braid, pre-stretched:

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⚠️ 5. Key Points to Watch

Excessive heat

Melting point around 140 °C → avoid rapid friction and misaligned winches.

Sharp edges / cutting abrasion

The fibre is strong but can be cut by sharp hardware.
→ Protect with a cover (polyester, Dyneema, Technora).

Creep

Like all UHMWPE fibres, it can lengthen slowly under constant high load.
→ For standing rigging, ensure proper oversizing.

Working load = breaking load / 5

Splice quality

A clean splice maximises performance.
→ This is why the 12-strand hollow braid is ideal.

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🏁 Why Choose Dyneema® SK99 for Your Boat?

Dyneema® SK99 is ideal if you want to:

✔️ Reduce weight in your rigging
✔️ Improve trim precision
✔️ Secure critical load points
✔️ Reduce friction and unwanted movement
✔️ Build clean, durable textile assemblies

It is one of the highest-performance fibres available, used by professional riggers and splicers in the most demanding applications.