Best Dock Lines for Boats: Material, Diameter and Length

Our top 3 picks

Stock checked on October 6, 2026

Top rated

4 Pack 1/2” X 15’ Dock Lines|Marine-Grade Double-Braided Nylon… 9.4 ★★★★★ BarcoEquipado score: 9.4 out of 10 See price

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AIRHEAD AHDL-4 Bungee, Dockline For Watercraft 4 Feet 9.2 ★★★★★ BarcoEquipado score: 9.2 out of 10 See price

Best value

RainierSupplyCo Dock Lines 2-Pack - Boat Rope for Docking with… 9.4 ★★★★★ BarcoEquipado score: 9.4 out of 10 See price

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How to choose dock lines

Choosing well is simple if you focus on three things: the material (nylon or polyester), the diameter for your boat size, and the length for each job. Then look at construction: a pre-spliced eye with a thimble saves time and avoids failures.

The practical rule is not to go skinny. The problem with thin line is not the weight of the boat, it is the snatch loads that waves and wind create at the dock.

Line diameter and length by boat length

Boat length	Diameter	Bow and stern lines	Spring lines	Minimum set
Up to 20 ft (6 m)	3/8 in	15-20 ft	20-25 ft	4 lines
20-26 ft (6-8 m)	1/2 in	20-25 ft	25-40 ft	4 lines
26-33 ft (8-10 m)	1/2-9/16 in	25-33 ft	33-50 ft	4-6 lines
33-40 ft (10-12 m)	5/8 in	33-40 ft	40-60 ft	6 lines
40-50 ft (12-15 m)	3/4 in	40-50 ft	50-65 ft	6 lines

Check that the diameter fits comfortably in your cleats and chocks: a small cleat with a fat line will not hold well, and thin line can slip.

Nylon, polyester and other materials

• Double-braid nylon: stretches under load and returns to length, acting like a spring. The most common choice for dock lines, ideal where there is surge, wake or big tidal range.
• Three-strand nylon (twisted): very elastic and easy to splice by hand. Popular for anchor rodes and as a shock absorber.
• Polyester (double braid): low stretch, excellent UV and chafe resistance, does not kink. Comfortable in sheltered marinas, though it transmits more of the jerk.
• Polypropylene: floats, but breaks down in sunlight and chafes quickly. It suits rescue lines, not permanent mooring.

How to tie up your boat properly

Alongside a dock you normally use four lines: bow, stern and two springs, one leading forward and one aft, which stop the boat from surging back and forth. If your marina uses mooring pilings or a pier with finger slips, lines run from both sides of the boat to the pilings, crossed where needed.

Always hang your fenders at dock height and leave some slack in the lines where there is tide. To make fast you need a cleat hitch, a bowline and a clove hitch; we cover them in basic boating knots.

Looking after your dock lines

• Rinse with fresh water at the end of the season and dry in the shade.
• If stiff with salt, wash with mild soap; the line regains flexibility.
• Use chafe guards at chocks and dock edges, because chafe can cut a line in weeks.
• Check the eye splices: if the splice opens or the thimble falls out, replace the line.

Replace lines when they are stiff, faded, have broken fibers or show the core at chafe points. One check per season is enough.

Common mistakes when mooring

• Lines that are too thin "because the boat is small."
• Using hardware-store polypropylene for permanent mooring.
• Tying up so tight that the lines cannot cope with tide or boat movement.
• Tying up alongside without spring lines: the boat surges and bangs.

Our team compares spec sheets, verified reviews and real-world criteria but does not physically test products. Always confirm material, diameter and length on the listings above.