Do you know the ropes? How sailing lines differ and how to extend their life

Everything you ever wanted to know about sailing lines and ropes but were afraid to ask. Which materials are best? And why you need to be mindful of what nautical knots you tie.

Few people know what material their rigging is made of and what to expect from it. Choosing the right lines for a boat can make our job a lot easier, leaving us more space to enjoy the sailing. So, which are the right materials, how can you extend their life and what's the best way to store them? And when it comes to tying sailing knots, which ones can reduce the strength of the line and why? Read on to find out more.

Types of ropes used on boats

Ropes are produced in several different ways depending on what they are intended for and which properties need to be enhanced or maintained. The two main types are twisted rope and braided rope.

Lanyard and anchoring lines must be able to withstand mechanical and chemical stresses

Twisted ropes are created by first twisting individual fibres into strands and then twisting the strands together in the opposite direction, using 3, 4 or even 12 strands. How strongly the individual strands are twisted gives the rope its individual characteristics.

Tightly twisted strands make the rope tough and unyielding whereas loosely twisted strands leave the rope flexible and soft. Ropes may also be braided. Both twisted and braided ropes can also be finished off with another braided “sheath” protecting the inner rope core.

Sailboat line materials

Rope properties are determined not only by the production method, but above all by the material used. The combination of these elements then determines how the rope will behave, how rigid or flexible it will be and whether it is durable or flexible.

Polypropylene (PP) lines

On a boat, one of the key characteristics is whether a given rope floats. Polypropylene floats and has excellent resistance to the weather, UV and abrasion. That's why we usually find polypropylene ropes as tow and rescue lines, e.g. on the orange line where the lifebelt is attached at the stern. The person being rescued will definitely appreciate you throwing them a line that doesn't immediately sink. As a result, PP ropes are produced in striking, brilliant colours. Polypropylene is also used for mooring. Here too, the advantages of a floating rope are obvious, is strong, and resembles natural materials.

YACHTING.COM TIP: Man Over Board (MOB) is something no sailor wants to experience. But when it happens, you need to know how to react quickly and correctly, because lives are at stake. Both the skipper and crew are under enormous stress the moment someone falls into the sea, so it is crucial to know the different steps to take and understand your role during a rescue operation. For a recap, check out our article — Man Over Board (MOB): a step-by-step guide.

Polypropylene rope

Polyamide (PA) or nylon ropes

Polyamide ropes, on the other hand, are not the most suitable as water greatly reduces their strength. After contact with water, a PA rope draws a considerable amount of moisture into its structures and the rope strength decreases dramatically. Even an increase of about 6% in weight will reduce the strength of such a rope by a third!

It is clear that polyamide (nylon) ropes are not very suitable for sailing due to exposure to both saltwater and freshwater. They are produced much less than the others and are used almost exclusively for mooring and anchoring ropes, where they must be considerably oversized.

However, they are exceptionally elastic but harden with age and need to be protected from ultraviolet radiation. PA can also be found on the boat in the form of thin lines to tie flags and alike. Nylon also hardens in seawater but the load capacity returns to the original levels after proper drying.

Modern machine spins nylon rope

Polyethylene (PE) ropes or HMPE

In comparison, Polyethylene is solid, tough and isn’t affected by water at all. In ropes today it is mainly found in the form of HMPE — high modulus polyethylene, high-density polyethylene. It is up to eight times stronger than steel ropes despite being up to eight times lighter. It is also resistant to chemicals and floats. Minimal elasticity also makes them a favourite for small boats and racing yachts. However, their major drawback is that they lose a huge amount of strength when knotted.

Polyester (PES) ropes

Polyester ropes (PES) do not float in water, but they are strong and UV resistant. Polyester ropes are therefore used for a multitude of functions on board a yacht — from halyards and sheets to mooring lines. They also have the advantage of being abrasion-resistant, and even when wet they remain flexible and soft.

Braided polyester rope

Today, as demands for specific rope properties increase, manufacturers are also using various combinations of synthetic materials to achieve the best and most desirable characteristics.

Storing ropes on a boat

Ropes can be safely stored for up to five years, under certain conditions. Store them in a clean, dark place at room temperature and humidity. We try to protect them especially well from chemicals that can unnoticeably reduce their strength to almost nothing! Battery acid, diesel, kerosene ... can all be complete rope killers.

Proper storage doesn't only minimize material degradation and other negative structural changes — there are studies that have shown that good storage even results in an improvement in some rope properties. Of course, the greatest enemy of the ropes at sea is the sun. With some ropes, you can't do anything but accept this, whereas others should always be carefully cleaned and stowed away.

What not to do with ropes?

It's probably obvious that the ropes should be protected against excessive load, friction, chemicals and dirt, as well as the sun. It’s also best not to step on the ropes. It is not just an old naval superstition, it also has a very practical reason — dirt from the soles of your shoes on the ropes can lead to damage under load.

Check the lines regularly. You should always be concerned when you find any hardened spot (probably friction damage), a damaged or significantly shifted braid, or a reduction in the diameter of the core beneath the braid (most likely tearing or pinching of the core).

You should untie all knotted, tangled areas as well as the knots themselves. If the rope has more load on one of its ends, you should regularly swap and re-tie the ends. 

Example of a not-so-old mooring line that broke under strain on the windward side of the boat

How types of knot affect sailing line strength

You may have already noticed that a loaded rope with a knot breaks most often where the straight part enters the knot. It is common for knots to reduce the strength of the rope to which they are tied by 30–60 % compared to a straight line without one.

See below the reduction in strength for specific knots. Can this problem be avoided? Basically not. Most knots on the yacht will need to be untied and re-tied repeatedly. The only way to minimize the reduction in rope strength is to braid them together. However, this can only be applied to specific ropes and only at their end. In addition, braiding lines together is time-consuming and requires considerable experience. 

How much do specific knots reduce line strength?

  • End of figure-eight knot by 55 %
  • Reef knot by 55 %
  • Sheet bend by 50 %
  • Rolling hitch by 48 %
  • Bowline knot by 36 %
  • Figure-eight loop by 35 %

Ukázka zaplétané smyčky, která téměř nesnižuje pevnost lana

YACHTING.COM TIP: Ropes are one of the most important things on board any yacht and you simply can’t do without their ability to fasten, join and connect. Learning at least a few basic sailing and boating knots is absolutely essential for sailing, anchoring and mooring. As it isn't just novices who make mistakes, we've prepared a guide to the 9 most important sailors knots for all your boating needs.

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FAQ about types of boat ropes