Choosing and replacing lines: mooring lines, sheets, halyards
How to choose the diameter and type of rope for mooring lines, sheets and halyards, and replace them safely.
Rope on a yacht is divided by function, because each type has different mechanical demands. Mooring lines have to be elastic to absorb snatch loads, so three-strand polyester or polyamide (nylon) is used. Sheets work dynamically and are often handled by hand, so grip, low stretch and abrasion resistance matter. Halyards, in turn, need minimum stretch so the sail keeps its shape, which is why they are built with a core of high-modulus fibres such as Dyneema (HMPE) or aramid.
The diameter depends on the size of the yacht and the working load limit (WLL), not only on breaking strength. A practical rule for cruising yachts: for a 30–35 footer, mooring lines 14–16 mm (0.55 in–0.63 in) (nylon), main and genoa sheets 10–12 mm (0.39 in–0.47 in), halyards 8–10 mm (0.31 in–0.39 in) with a low-stretch core. Remember that the diameter often follows ergonomics and the capacity of the winch drum and clutches, not just strength. Always check the maximum diameter allowed by the maker of the blocks and winches.
Materials differ in resistance to UV, abrasion and water. Polyester (PES) is the all-round choice for running rigging: good UV resistance, low stretch, a sensible price. Polyamide (nylon) has high elasticity and strength, but loses around 10–15% of its strength when soaked and stretches more, which makes it ideal for mooring and anchor lines. HMPE (Dyneema) has strength close to steel with minimal weight and almost no stretch, but it is more expensive, needs special knots or splices and creeps under constant load.
Before replacing, measure the old rope carefully, allowing for the eye splice and finishing the ends. Mooring lines are usually about 1–1.5 hull lengths, springs a little longer. A halyard has to reach from the attachment point on the sail over the masthead sheave to the winch and clutch, with a working allowance. The easiest way to run a new line is with the old one: sew or tie the ends together (a messenger), tape the joint and pull it through the mast, avoiding jamming at the join.
Rope ends have to be protected from fraying. Synthetic ropes are best sealed with heat (melted and shaped), with a protective whipping in waxed twine added on top. Eyes are spliced with the technique for the construction: a core-to-cover splice for braided rope, a classic eye splice for three-strand. Ready-made eyes with a swaged thimble (talurit) are convenient, but on working ropes a hand splice keeps a higher percentage of the strength and can be repaired.
Rope wears out gradually, so assess it regularly. Signs that it needs replacing are: chafe in the cover exposing the core, hardening and internal wear (the rope loses elasticity), fading and brittleness from UV, and local narrowing. Check mooring and anchor lines especially where they touch fairleads and cleats. Wash rope in lukewarm water with a mild detergent, without bleach or solvents, and after the season dry it and store it in a ventilated, shaded place.
When choosing, read the manufacturer's data: breaking strength, stretch at a given load and the recommended use. Reputable makers such as Marlow, English Braids and Robline publish diameter selection tables. Do not exceed the working load, and use a safety factor (typically 5:1 for running rigging). Remember that old, degraded gear is an injury risk when it breaks under load.
Material prices — products and options
Indicative prices in EUR (incl. VAT), as of July 2026. Products widely available in Europe; prices depend on the shop, the pack size and consumption. The links lead to example shops that ship across the EU. Dollar amounts are converted at 1 EUR = 1.1622 USD (ECB, 7 September 2026) and rounded — treat them as a rough guide, not a price in a US shop. Imperial values in brackets are conversions of the metric figure.
Rope for halyards and sheets (braided polyester, 8–12 mm (0.31 in–0.47 in))
- Liros — Herkules 10 mm (0.39 in)
braided polyester, low stretch, for sheets and halyards (mid-range)€3–5 (≈$3–6)/m (approx.) - Robline — Sirius 300 / Sirius Grip 8–10 mm (0.31 in–0.39 in)
soft, excellent grip in gloves, for sheets and tackles (mid-range)€3–6 (≈$3–7)/m (approx.) - Marlow — Doublebraid 10 mm (0.39 in)
all-purpose double-braid polyester line, halyards and sheets (mid-range)€3–6 (≈$3–7)/m (approx.) - Gleistein — running rigging line
German polyester line for halyards and sheets, good durability (premium)€4–8 (≈$5–9)/m (approx.)
Mooring lines and springs (nylon, 12–16 mm (0.47 in–0.63 in))
- Liros — Seastar / nylon mooring line
polyester or polyamide for mooring lines and springs (mid-range)€3–7 (≈$3–8)/m (approx.) - Three-strand polyamide line 14–16 mm (0.55 in–0.63 in)
three-strand nylon that absorbs snatch loads, for mooring lines (budget)€2–5 (≈$2–6)/m (approx.) - Ready-made mooring line with an eye (factory splice)
made-up mooring line with a spliced eye, various lengths (premium)€15–45 (≈$17–52)/piece (approx.)
Materials for ends and whippings
- Waxed whipping twine
for finishing rope ends and protective whippings (budget)€4–12 (≈$5–14) (approx.) - Self-adhesive / self-amalgamating tape for rope ends
quick protection for rope ends (budget)€4–10 (≈$5–12) (approx.)
Sailmaker's tools
- Splicing fid and sailmaker's needle
set for making splices and eyes (mid-range)€8–25 (≈$9–29) (approx.) - Rope knife / hot knife + tape measure
knife or soldering iron for sealing the ends, tape measure (mid-range)€8–30 (≈$9–35) (approx.) - Work gloves (old rope as a mouse)
gloves for handling rope; a messenger made from old line (budget)€5–20 (≈$6–23) (approx.)
Price sources: svb24.com, compass24.com and the manufacturers' websites (Liros, Robline, Marlow, Gleistein). Indicative prices — check the current ones with the seller.