CHOOSING THE CORRECT DOCK LINE

Choosing the Right Nylon Double Braided Dock Line for Your Boat

 

Boat Length Nylon Rope Diameter
  Metric Inches
Boats under 20 feet or 6 metres in length 10mm 3/8"
Boats from 20 to 30 feet or 6 to 9 metres in length 12mm 1/2"
Boats from 25 to 35 feet or 8 to 10 metres in length 14mm 9/16"
Boats from 30 to 40 feet or 9 to 12 metres in length 16mm 5/8"
Boats from 40 to 50 feet or 12 to 15 metres in length 18mm 3/4"
Boats from 40 to 50 feet or 15 to 21 metres in length 20mm 4/5"

 

As a general rule, the length of bow and stern lines should equal two-thirds of your boat's overall length. Spring lines should be slightly longer, approximately the same length as your boat. Spring lines keep the boat snugly near the dock by preventing it from moving fore or aft, while allowing for the rise and fall of the tide. Keep in mind; the position of cleats on your boat and dock may affect the length of the dock line.

Unless your boat is unusually heavy or will be subjected to severe conditions, a bow line, stern line, and two spring lines are recommended. If your permanent slip has outboard pilings as well, you will need an additional bow and stern line.

Whitsunday Discount Marine only recommends using nylon rope for dock and mooring lines; the stretch characteristics of nylon absorb shock and will resist damaging cleats on your boat and on your dock.

Our nylon and polypropylene docking ropes are only available in double braid solid core or yacht braid for improved strength and durability. Each has a 300mm loop spliced at one end.

COMPARISON OF BREAKING AND WORKING LOADS OF ROPES

  Braided &      3 Strand Dyneema Core Nylon Polyester Polypropylene (Silver)
Rope Size
Breaking Load
Kg
Working Load
Kg
Breaking Load
Kg
Working Load
Kg
Breaking Load
Kg
Working Load
Kg
Breaking Load
Kg
Working Load
Kg
8mm 2,200 610 1,215 338 918 255 630 175
10mm 3,400 950 1,872 520 1,431 398 981 273
12mm 7,200 2,000 2,700 750 2,043 568 1,386 385
14mm     3,690 1,025 2,862 795 1,881 523
16mm     4,770 1,325 3,690 1,025 2,520 700
18mm     6,030 1,675 4,635 1,288 3,150 875
20mm     7,470 2,075 5,760 1,600 3,870 1,075