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daN or kg? How to read loads on marine ropes (without getting it wrong)
You read “500 daN” on a rope product datasheet, but you wonder what that represents in kilograms? No worries. In this article, we explain the difference between force (daN) and mass (kg), and above all how to interpret them to properly choose your marine ropes.
🔍The kilogram (kg): a unit of mass
The kilogram is a unit of mass that measures the amount of matter in an object. On Earth, this mass is subject to gravity, which generates what we call “weight”. For example, a 1 kg object is subjected to a force of approximately 9.81 newtons.
⚙️ The decanewton (daN): a unit of force
The daN is a unit of force. 1 daN = 10 N. It is a direct measurement of the load applied to an object, such as the tension on a rope.
📏 Practical conversion: 1 daN ≈ 1 kg
On Earth, it is commonly rounded: 1 daN = 1 kg. This approximation is based on Earth’s gravity (9.81 m/s²). It allows a fast and intuitive reading of rope loads.
Practical example:
A rope rated with a breaking strength of 500 daN can therefore withstand a force equivalent to approximately 500 kg under normal conditions.
A rope rated with a breaking strength of 500 daN can therefore withstand a force equivalent to approximately 500 kg under normal conditions.
🛥️ Marine application: choosing the right rope
On a sailboat, it is essential to choose a rope suited to the loads it must handle. A safety factor of 5 is generally applied:
Working load = Breaking load / 5
If your sheet or halyard is subjected to a working load of 250 daN, it must have a minimum breaking load of 1250 daN.
👉 On-board example:
• Mainsail halyard (30–35 ft sailboat): working load ~200–300 daN
➡️ Recommended rope: HMPE core halyard with polyester cover
• Genoa sheet: dynamic loads + friction
➡️ See our technical polyester / HMPE sheets
• Mainsail halyard (30–35 ft sailboat): working load ~200–300 daN
➡️ Recommended rope: HMPE core halyard with polyester cover
• Genoa sheet: dynamic loads + friction
➡️ See our technical polyester / HMPE sheets
⚓ Recommended Marine Ropes
🧵 How to use this information for your ropes?
- Check the breaking strength in daN on each rope datasheet.
- Apply a safety factor to determine the actual working load.
- Choose the diameter and material accordingly (Dyneema, HMPE, polyester).
Hesitating between several diameters or materials?
👉 Guide: how to choose the right rope for your boat
📌 Useful reminder
daN = force measurement.
kg = mass measurement.
On Earth: 1 daN ≈ 1 kg to simplify calculations in sailing, marine use and handling.
Which rope for your sailing program?
- Coastal cruising → Marine-grade polyester
- Long-distance cruising → Covered HMPE (less stretch, longer lifespan)
- Performance / racing → Pure or technically covered HMPE
👉 Discover ropes suited to your sailing program
📚 Additional technical guides
⚓ Summary
Understanding the relationship between daN and kg helps you properly read rope datasheets and choose equipment suited to your boat. This improves safety, performance and durability.
Unsure about the actual load on your halyard or sheet?
Send us your boat type and usage, we’ll get back to you.
