How to Choose the Right Mooring Lines for Your Boat

Securing a boat in the marina or on a mooring always starts with choosing the right mooring lines. A boat mooring line isn’t just there to keep the boat alongside: it absorbs shocks, protects deck hardware, and keeps both your crew and neighbouring boats safe.

Reusing an old sheet might feel economical, but it often leads to premature breaks and accelerated wear. In this guide, you’ll learn how to choose your mooring lines using practical criteria: material, construction, diameter and length.

3-strand polyamide mooring line: designed to absorb shocks while docked.

Why choosing the right mooring lines matters

Mooring lines are your boat’s first line of defence against wind, chop and harbour movement. Poor mooring lines can cause:

• violent snatching loads on cleats and fairleads,
• premature line wear,
• a real risk of failure in bad weather.

A good mooring line must both absorb shocks, stay strong and remain easy to handle over time.

The key criteria of a good boat mooring line

An effective mooring line should:

• Absorb movement thanks to controlled stretch
• Resist breaking despite wear (UV, abrasion, salt)
• Stay supple for easy knots and handling
• Withstand the marina environment (pollution, chafe)

Remember: the heavier or more exposed the boat, the more elastic and oversized the mooring line should be.

Mooring-line constructions that work well

3-strand rope

Pros: high stretch, cost-effective, easy to splice
Cons: can kink over time, may stiffen

➡️ Recommended for classic mooring lines and cruising boats.

Square line braid – 8 strands (4x4)

Pros: supple, anti-twist, good shock absorption
Cons: can fray

➡️ Great for moorings; runs well on capstans/windlasses.

Double braid

Pros: very robust, controlled wear, excellent hold
Cons: lower stretch, higher price

➡️ Suited to heavier boats.

Single braid

Pros: very light, easy handling, compact
Cons: slightly lower strength

➡️ Suited to racing sailboats, RIBs and dinghy sailing.

Which material should you choose for your mooring lines?

Polyester

• Pros: excellent UV & abrasion resistance, low water absorption, durable
• Cons: moderate stretch
• Best for: main long-term dock lines

👉 See our polyester mooring lines

Polyamide (nylon)

• Pros: higher stretch, great shock absorption
• Cons: absorbs water, can stiffen with age
• Best for: spring lines, rough marinas

👉 Discover our polyamide mooring lines

Polypropylene

• Pros: floats, very light
• Cons: weak UV & abrasion resistance
• Best for: temporary use or emergency

Recommended diameter for boat mooring lines

The diameter of a mooring line mainly depends on your boat length and the material used.

Pro tip: in exposed areas (chop, current, prevailing wind), go up one size.

👉 Choose the right mooring-line diameter

How long should your mooring lines be?

Recommended standard setup:

• 2 lines at 1 × boat length (bow/stern)
• 2 lines at 2 × boat length (main/long lines)
• 1–2 extra long lines for locks or rafting up

Example – 10 m boat: 2 × 10 m + 2 × 20 m + 1 long line (25 m).

Why choose spliced mooring lines?

• Strength: a splice keeps up to 90% of the breaking load
• Durability: less wear, no weak points
• Convenience: quick, clean and secure installation

Combined with a stainless-steel thimble, spliced lines are ideal for long-term marina use.

Useful accessories for safer mooring

Conclusion: choosing the right mooring lines

Choosing the right mooring lines means finding the right balance between material, construction, diameter and length. Generous sizing and quality splices improve safety, comfort at the dock and the lifespan of your lines.

Need ready-to-use dock lines? Gorilla Ropes makes custom spliced mooring lines tailored to your boat and your sailing programme.

👉 Discover our Made in France mooring lines

📞 Need personalised advice?

Contact us

High-Quality Marine Ropes – Made in France – Gorilla Ropes
www.gorillaropes.com

Tags: boat mooring lines, mooring line, dock lines, boating safety, polyester, polyamide, mooring