In every key aspect of performance – strength, stretch, weight, durability, and resistance to the elements – Dyneema® outperforms polyester by a wide margin.
Strength and weight
Dyneema®’s exceptional strength-to-weight ratio means a Dyneema® rope of just 8 mm diameter can hold a load of around 3,000 kg – roughly twice what polyester can do at the same diameter. Despite this, Dyneema® is light enough to float.
Low stretch and sail control
One of the most significant differences between Dyneema® and polyester is elastic elongation. While polyester lines typically elongate by 3–4% under working tension, Dyneema® SK78 fiber lines stretch by only 1–1.5%. This seemingly small difference has a significant impact on sailing performance.
Dimensional stability
High-grade Dyneema® fibers such as Dyneema® SK78 and DM20 fibers exhibit minimal plastic elongation under sustained load. This makes them ideal for halyards, vangs, and standing rigging, where consistent tension is critical. Polyester is more stable than nylon, but it still exhibits measurable permanent elongation over time. This can result in slack rigging and loss of performance.
Durability and service life
Dyneema®’s greater resistance to fatigue and abrasion mean that ropes made with Dyneema® significantly outlast polyester lines, which gradually lose elasticity and strength due to internal heat buildup and moisture absorption. Where Dyneema® lines maintain their performance over time, polyester lines soften, become heavier, and grow more elastic, requiring replacement sooner.
Chemical resistance
Dyneema® is resistant to most acids, alkalis, and solvents, and is completely unaffected by saltwater. It does not rot or degrade in damp conditions, and it maintains its properties after years of exposure. Dyneema® ropes nearly always include an outer cover, or sheath, for grippier handling. This cover, often made with polyester or a polyester / Dyneema® blend, has the added benefit of ensuring Dyneema® ropes withstand the effects of UV radiation as well as other synthetic ropes. In contrast, polyester is more susceptible to chemical attack from acids and alkalis.
Handling and efficiency
Dyneema®’s smooth, low-friction fibers run efficiently through deck hardware and sheaves. They resist chafing and require less energy to trim or hoist sails. When paired with blended or polyester covers, they also provide excellent grip and tactile comfort. Polyester lines are soft and flexible, but they can flatten under load and slip in clutches. They also absorb water, which increases weight, handling effort, and friction.