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Mooring Warps Size Guide

General guide for determining the diameter of your mooring lines

These are the Important Decision Factors:

Moorings can be broadly divided into three categories:

  1. Shoreside, e.g. Jetties, pontoons (fingers), piers, and harbour walls, but could also include any convenient tree or rock.
    • Mooring alongside a fixed structure (along her length) with several lines to share the load and restrain her movement
    • Mooring stern to (perpendicular to the shore) with stern mooring lines to the shore and utilising anchor lines deployed beyond her bow to maintain her angle to the shoreline
  2. Permanent Anchor Mooring: permanent attachment to the sea bed at a single fixed point or as part of a series.
    • Swinging Mooring – a single mooring is generally a single anchor or weight laid on the sea bed and connected to a buoy on the surface. A mooring attached to a series of anchors or weights on the sea bed (also known as a trot) is still swinging if the connection is individual, i.e. allows swing. Swinging refers to the fact that a yacht secured to a single point can turn full circle in either direction, according to the wind and tide. The buoy can be identifiable as a yacht’s home or a visitor's mooring. Sea bed mooring points vary from purpose-designed anchors to concrete weights according to local conditions. The sea bed anchor is typically attached to the mooring buoy with a chain known as the riser. A yacht is generally attached to the mooring buoy with a substantial, chafe-protected mooring rope commonly referred to as a strop or a bridle.
    • Pile Mooring: poles driven into the bottom of the sea bed or river bed in a regular line, with their tops protruding the surface to a serviceable height. A yacht positions herself in line between two piles and deploys mooring lines fore and aft to a heavy steel ring on the pile (which may slide up and down with the tide).
  3. Running or Travelling: a fixed anchorage on the seabed with a block attached. A long line is reeved through the block, and each end leads back to the shoreline, where it is spliced together to form an endless loop. A rope is attached to the running rope to act as a riser. This type of mooring is prevalent for dinghies and tenders, which can be moored at a distance from the shore but easily pulled back in for embarkation.

How to Select the Right Diameter Rope for your Mooring Warps

There are two significant factors in determining the adequate rope diameter for your mooring requirements:

1. Selection process for the diameter of General Use Mooring Lines (Shoreside):

  1. Find the column below that best represents your Boat Length Overall.
  2. Compare your displacement with the tonnage listed.
  3. If the displacement is greater than displayed in your column in the table, or the yacht is a multihull, consider moving across to the next column to increase the diameter.
  4. Have a good look at the mooring lines on neighbouring yachts with a critical eye and judge whether your setup should be the same or whether you can make improvements
  5. Take local conditions into account - some marinas are notorious for excessive movement (wave motion) when the wind is strong from a specific direction affording relatively little protection.
  6. Decide whether an upgrade would enhance your mooring convenience
  7. Add anti-chafe measures and compensators for peace of mind and fewer replacement costs
  8. Bear in mind that several correctly deployed mooring lines can share the overall strain - more mooring ropes should result in less load on each warp and, consequently, less shock impact on your deck fittings.

NB. Consider upsizing your Stern Mooring Lines when moored stern-to (Mediterranean style) because the strain on the ropes will be considerably greater than when your yacht is moored alongside a pontoon.

Consider doubling up your stern-to mooring lines for Mediterranean Style Mooring as a precaution, especially when leaving your yacht unattended for any length of time.

Benchmark Rope Diameter Guide for Multipoint Mooring Alongside Lines - Yachts up to 16 metres LOA
Yacht Length Overall < 6 metres 6-8 metres 8-10 metres 10-12 metres 12-14 metres 14-16 metres
Approximate length in feet < 20 feet 20-26 feet 26-33 feet 33-40 feet 40-46 feet 46-53 feet
Displacement in Tonnes 1 tonne 2.5 tonnes 5 tonnes 9 tonnes 13 tonnes 16 tonnes
3 Strand, Dockline, Octoplait Polyester 8/10mm 10mm 12mm 14mm 16mm 18mm
Anchorplait, Handy Elastic, 3 Strand Nylon 8/10mm 10mm 12mm 14mm 16mm 18mm
Moorex12 Polyester, 3 Strand Polypropylene 12mm 14mm 16mm 18mm 20mm
Benchmark Rope Diameter Guide for Multipoint Mooring Alongside Lines - Yachts over 16 metres LOA
Yacht Length Overall 16 - 18 metres 18 - 22 metres 22 - 26 metres 26 - 30 metres 30 - 36 metres 36 - 50 metres
Approximate length in feet 53 - 60 feet 6- 72 feet 72 - 85 feet 85 - 98 feet 98 - 118 feet 118 - 164 feet
Displacement in Tonnes 20 tonnes 25 tonnes 30 tonnes 40 tonnes 70 tonnes 100 tonnes
3 Strand Polyester 18/20mm 20/24mm 24mm - - -
Dockline 18/20mm 20/24mm 24mm - - -
Octoplait / Anchorplait 18/20mm 20/24mm 24mm - - -
Handy Elastic 18/20mm 20/24mm 24mm 28mm 32mm -
Super Yacht Mooring 01300 (Dockline) - - 24mm 28mm 32mm 36mm

N.B. LIROS Super Yacht Mooring Line Article 01300 is the LIROS recommended dockline for yachts over 22 metres LOA 

2. Selection process for a Single Point or a Double Point Mooring Configuration (Permanent Mooring):

  1. Find the column in the table below that best represents your Boat Length Overall.
  2. Compare your displacement with the tonnage listed.
  3. If the displacement is greater than displayed in your column in the table, or the yacht is a multihull, consider moving across to the next column to increase the diameter.
  4. Take advice on local conditions and check the benchmark size from the table below against other similar sized boats moored in your area.
  5. Look at the mooring configurations on neighbouring yachts with a critical eye and judge whether your setup should be the same.
  6. Consider whether you can make any improvements in terms of mooring convenience and anti-chafe measures.

Benchmark Guide for Single Point Mooring Strops e.g. permanent home buoy swinging mooring
including Fore and Aft (double point) Mooring

Yacht Length Overall < 5 metres 5 - 6 metres 6 - 8 metres 8 - 10 metres 10 - 12 metres 12 - 14 metres 14 - 16 metres
Approximate length in feet < 16 feet 16- 20 feet 20 - 26 feet 26 - 33 feet 33 - 40 feet 40 - 46 feet 46 - 53 feet
Displacement in Tonnes 0.6 tonnes 1 tonnes 2.5 tonnes 5 tonnes 9 tonnes 13 tonnes 16 tonnes
Strop Diameter 14mm 16mm 18mm 20mm 24mm 28mm 32mm

3. Selection process for a Rope/Chain/Rope Bridle (Visitor Mooring):

  1. Find the column below that best represents your Boat Length Overall.
  2. Compare your displacement with the tonnage listed.
  3. If the displacement is greater than displayed in your column in the table, or the yacht is a multihull, consider moving across to the next column to increase the diameter.
  4. Consider the application for your bridle - Will it be used as a single or double mooring point or as an anti-chafe mechanism to protect your regular lines
  5. Consider the nature of the application - the chart is conservative and aimed at an overnight visit; consider upgrading to the next column for a more permanent arrangement or on an exposed mooring

Benchmark Guide for Rope / Chain / Rope Bridles

Yacht Length Overall 6 - 8 metres 8 - 10 metres 10 - 12 metres 12 - 14 metres 14 - 16 metres
Approximate length in feet 20 - 26 feet 26 - 33 feet 33 - 40 feet 40 - 46 feet 46 - 53 feet
Displacement in Tonnes 2.5 tonnes 5 tonnes 9 tonnes 13 tonnes 16 tonnes
Anchorplait / 3 Strand Nylon 14mm 16mm 18mm 20mm 24mm
Chain 8mm 10mm 10mm 12mm 12mm

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