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Article: Mooring Warps

Mooring Warps

Mooring Warps

You never know when it might blow up a bit!

There’s no right or wrong with your choice for mooring warps. I’m sure lots of seasoned sailors will have different opinions to me. This is just a collection of my thoughts that may be of some help before selecting your mooring warp.

We need to consider:

  • The material the rope is made from
  • The construction of the rope
  • The diameter or strength of the rope
  • The length of the rope and the size of any eye or loop
  • Chafe protection


Let’s kick off with the material. I’m going to stick my neck out and say polyester is the best material for mooring warps. OK, I know it is conventional wisdom to choose Nylon because it is so stretchy but therein lies a problem. For short bow and stern lines Nylon could well be a good choice to avoid snubbing but for long spring lines the amount of stretch in Nylon can cause the boat to surge along the pontoon in gusts. Fenders will roll back and forth and may eventually pop out. Assuming the right construction is chosen I find polyester has ample stretch to avoid snubbing but not so much stretch that the boat will surge back and forth. I also find Nylon goes stiff after a few years whereas Polyester seems to stay soft and manageable for ever.

Nylon is slightly stronger than polyester but loses some strength when it is wet. Polyester is unaffected by moisture.

What about the other materials?

Polypropylene has the advantage that it floats. If it has UV treatment it will last for a good few years, but not as long as Polyester. It is very economical to replace. It is a popular choice for narrow boaters, and it makes a handy painter for the dinghy. But we digress.

Natural fibres will certainly score a few brownie points environmentally. They need to be stored where they can dry naturally and aren’t as strong as artificial fibre ropes. Coir, made from coconuts, has amazing stretch properties and salt water actually prolongs its life. However, I’ve never supplied a coir mooring line - yet. You could maybe start a trend and report back.

Please, don’t even think about using Dyneema or Technora!


Stretch can be built into a rope by its construction. Some climbing ropes are designed to stretch more than the actual construction material itself can stretch. So, although a Nylon fibre will break at 30% elongation you can buy Nylon Climbing ropes that will stretch by 40%. Via the construction alone you can have a Polyester rope like Liros Herkules with a stretch of less than 5% and another Polyester rope such as Liros Octoplait which will stretch greater than 15%. Therefore the construction of the rope is very important. To reduce the stretch in a rope, sometimes a heat setting process is used. This is handy for halyards but not so good for mooring warps.

My choice of construction for a mooring warp would be a soft-lay matt finish three strand rope but I have a “classic” type of yacht and traditional ropes just look better. I use Liros Classic Matt Three Strand. Three strand ropes are very easy to splice. The ropes can be made to last longer if they are top-to-tailed every few years but obviously they will get slightly shorter each year if you are splicing a new loop into the end.

A modern yacht owner may prefer matching navy or black braided ropes which are fine but choose braided ropes that have been constructed for the purpose. These ropes are often called “Docklines”, Liros Porto being an example. Many ropemakers make Super Yacht Mooring Lines which are braided and designed for the purpose. Best to avoid using old halyards as mooring lines because they are probably pre-stretched.

Octoplait is an eight plaited rope often used as anchor warps but it is sometimes used as a mooring warp as well. It has a rumoured advantage of being non-squeaky. In fact, we supplied some Octoplait lines specifically for this purpose a little while ago - I wonder if they worked? Octoplait is very easy to handle and can be just bundled into a rope bags. There’s no need to coil it. My 60 m long kedging warps are made from polyester Octoplait and stored in special bags.

Diameter and Strength

Don’t over egg it. Polyester is quite heavy, well it sinks doesn’t it! Throwing a 20 mm diameter rope up the side of a deep lock is a lot harder than throwing a 14 mm rope up. Rope manufacturers will have a table of recommended rope diameters but they shouldn’t be taken as gospel because boat hulls behave differently. I remember a gale blowing through a harbour directly fore and aft on the yachts. My 26 ft long boat with a deep keel and weighing 5 tonnes just sat there dead still as the wind blew over her. The boat in front was a bit longer but much lighter. It also had a fin keel and no forefoot and it snatched from side to side in a totally alarming manner. It must have been untenable inside. My ropes were not being subjected to any snatch loads. The lighter boat probably required stronger lines than mine. Hence a table of sizes can only be a very rough guide.

The main cause of mooring rope failure is bound to be chafe so you also need to avoid buying a rope which is too thin even if its breaking load fits the bill. You need a bit of built-in obsolescence.

If your budget stretches, you may want to invest in a set of heavier winter lines and keep your summer lines light and easy to handle.

Length and Loop Sizes

Opinions vary but I would personally have my bow and stern lines as long as the boat plus a metre and my springs one and a half times as long as the boat plus a metre. The bow and stern lines will generally be doubled back to the yacht but the extra length can be handy when rafted out. This formula wouldn’t work on huge yachts who would end up with an unworkable pile of spaghetti.

However, before you decide, have a think about where you will be sailing. If you need to transit the Caledonian canal check what the recommended lengths are for working the locks. It would be silly to order 15 m lines, if you will need 18 m lines to make the transit. If you are thinking of drying out on a harbour wall in Brittany you will have a lot of tide to cope with. That said, long lines take longer to coil, and you may even need to coil them on the deck if they are too heavy, so try not to add any length just for the sake of it.  

If you are going to have a loop spliced into the rope, then it should match your cleats and ensure that the splice doesn’t foul on the fairlead. Spliced loops should always be twice as long as they are wide to avoid stressing the splice. So, if you need a loop to drop over a samson post it mustn’t be a tight fit. My 14 mm diameter warps have a loop with an internal length of 300 mm which works for me.

Adding a meter to the length you actually need, means you can resplice the tail end after a few years to avoid wear in specific places.

Chafe and Snubbing

If your fairleads are smooth and your cleats are well sized then there shouldn’t be excessive chafe. Some polyester sling tubing can be inserted into the eye which can help reduce wear. This can be colour coded to help identify the springs from the bow and stern lines.

Canvas rope protectors can help when your warps need to bend over a sharp harbour wall.

I’ve never found the need for anti-snubbing devices, but long keeled heavy displacement boats tend to be well behaved in this respect. If your yacht or boat snatches then adding a rubber snubber or stainless steel spring to your winter mooring lines could help. Some rubber snubbers can be inserted into the line without needing to thread the whole line through the holes.


If your spring lines are running over your varnished teak toe rail then take care as they can saw a deep groove in no time, best to add a tie to raise the line off the rail or clip a piece of chafe protection to the rail.


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