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Single & Double Braid Sailboat Lines Explained | Expert Advice

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Understanding the basic differences in line materials and construction will allow you to choose the best line for your application.  We will cover the differences between single and double braid line as well as their specific materials:

  • Single Braid Line / Hollow Braid
  • Single Braid Core / High Tech
  • Double Braid / Polyester
  • Double Braid / High Tech

Single Braids

Single braid lines are made up of eight or twelve strands braided into a circular pattern with half of the strands laying clockwise and the other half counterclockwise.  The center void may be either large or small in cross-section.  If it is a large void the line may be referred to as a hollow braid line, and if small, it may be referred to as a core braid.

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Single Braid Line

Single braid line, hollow braid

Hollow braided lines are intended to be hand-held and cleated.  They are generally soft, flexible, and low kink. They are easy to hold on to as they tend to be made of soft spun polyester, or a blend of polyester with Dyneema for lower stretch.  Single braids are often unideal on winches as they will not hold up to being eased off the drum under load, or may not take-up well in a self-tailer due to their less dense construction. Due to the lack of core, these lines don’t hold their shape especially well in areas where they are repeatedly cleated in a cam cleat; but this is usually not a performance issue unless the line is a small diameter relative to cleat to begin with.

Single braid lines are not recommended for use with jammers or clutches. The line abrades in the ‘teeth’ of the cams and the loose and coreless construction collapses too much to be effectively held.  Similarly, and as a side note, single braids have a tendency to ‘shrink’ in diameter a small amount when the line is highly loaded and the fibers are loaded, even when handheld.

Single braid lines are a good choice for easy-to-grip, hand adjusted lines like main sheets and control lines on dinghies, and keelboats up to 35’.

Single Braided Core

High tech single braided lines are basically the same as the tightly braided core found in high tech double braids (which we will cover a bit later).  They are most times a braid of 100% Dyneema which is UV stable, low stretch and highly abrasion resistant.  Single braided cores do not have covers, and are smooth and slippery, and therefore not intended for cleated or hand-adjusted applications.

Single Braid Core

The braid of these cores is compact and coated with a urethane treatment (available in many different colors) to ‘glue’ the braid together. This treatment keeps the braid tight and further protects the line from UV degradation and abrasion.

Single braid core lines make a good, lightweight replacement for wire rigging – strops, multi-block cascading purchases, lifelines, backstays (and in some cases shrouds).

Single braid tips:

TIP: The vast majority of single braid cores are made with Dyneema due to its superior overall performance – low stretch, high strength, and UV stability.  Because Dyneema does experience creep (the unrecoverable stretch – permanent elongation) and does not tolerate extreme heat well, some single braid cores will be made with either Technora or Vectran. These materials creep less and are more temperature resistant although have some drawbacks in other performance characteristics.

TIP: Adding a section of braided cover in short areas that require hand adjustment and cleating is an option, but generally stripping a high tech double braid is preferred. This way, the cover is braided directly to the core when manufactured – tight, balanced with no twist, optimal cover diameter to ‘grip’ the 100% load-bearing core (not slip).

Double Braid Line

Polyester (top) & High Tech (bottom) Double Braids

Double braids, also called braid on braid, consist of a braided core within a braided outer jacket.  Due to their symmetrical construction with equal numbers of strands laying one direction and opposed in the braid, the line will not impart twisting force when it is under load – no twists or kinks.  Double braids are used for the vast majority of all running rigging on sailboats (sheets, halyards and control lines) – cruising or racing.

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 Polyester Double Braid

Polyester line was introduced to sailing in the 1950’s and was the first ‘low stretch’ line as compared to traditional twisted lines of the day.  Double Braid Polyester lines are the workhorse for most applications on a cruising sailboat, from halyards and sheets, to control lines. Polyester is a relatively low stretch, high strength, UV resistant, and abrasion resistant.  The key to understanding a 100% polyester double braid line is to know that both the core and the jacket share the load equally.  Double braid polyester eye splices splice both the core and the jacket such that this load sharing is preserved.  If either the core or the jacket, independent of the other, has a blend of another fiber (like Dyneema, Technora or Vectran) this 50:50, cover/core, load sharing does not exist, and it is no longer a polyester double braid (and would require a high tech eye splice).

Although these polyester lines are low stretch, they do have some elastic stretch compared to high tech double braid lines – up to 4 or 5 times more.  If a highly loaded polyester halyard were to slip one or two inches, in say a clutch, the elastic recovery of the line would make this virtually unnoticeable and would not substantially change the load on the line. So, Polyester is very forgiving compared to a high tech double braid line that has virtually no elastic recovery.  Also, Polyester lines are less demanding on clutches, as all parts of the line are load bearing, and perform best in them over all other line types – less slipping.

Double braid polyester line is low maintenance, affordable, and long-lasting. It offers relatively low stretch and high working loads.  Before considering a high tech, high performance, higher priced line, be sure there is a true performance need.  The majority of cruising boats will use double braid polyester for all running rigging applications, while racers may require many or most lines to be high tech due to the extreme loads involved, and need for the lowest stretch to maximize performance to the nth degree.

 High Tech Double Braid

High tech double braids, or core dependent lines, offer exceptionally low stretch and high working loads compared to double braid polyester lines.  The braided core is typically Dyneema, Technora or Vectran. These high tech materials create a core that takes 100% of the line load.

The cover is braided over the core to allow you to handle, cleat, clutch, and winch the line, while protecting the core from wear and UV degradation. These covers are not intended to be load bearing.  Because the core takes all of the load, it is important that the cover is firmly attached to it.  If the cover were to slip under load, the jacket (cover) would begin to take on the high tech core’s (higher strength, lower stretch) load, and begin to abrade in cleats, jammers, and clutches, and eventually fail.  To prevent this you need to ensure that your cover is always tightly attached to the core so that it grips and holds it (think Chinese finger trap).  If there is looseness in the cover (at any point in the life of a line), it will need to be removed.

High tech double braids will have coated cores (color-coded to match the covers) which allow you to strip the cover off to save weight in areas that are not handled, cleated, clutched or winched.  This is generally something that is done on racing boats to save weight (especially with halyards), but at the cost of the protection, the cover provides the core.  The coating on the core helps to keep the fibers ‘glued’ together, and provide additional UV and abrasion protection in lieu of the cover.  If you have a racer/cruiser boat, and weight is not critical, leaving the cover on will provide a longer service life.

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High Tech Tips:

TIP: Remove the excess cover by securing the working end to a fixed point, cutting off any whipping on the bitter end, and ‘milking’ the cover down its entire length by hand.  The excess cover slides off of the bitter end where it is cut flush with the core and whipped again.

TIP: If you are not stripping the cover on your new halyard(s), request them a few feet longer than needed.  When the line begins to wear, cut off your end splices, splice the opposite ends, and run it in the opposite direction.  This will give cleats, clutches, winches and exit sheaves a virtually ‘new’ area of the line to wear against and extend the lines life.

TIP: If you are upgrading a racer/cruiser sailboat for more competitive racing, switching from double braid polyester lines to high tech double braids may give you a noticeable boost in performance in two ways.  First, new sails (especially laminate sails) perform better with lines that are low stretch and do not stretch (adjustments to sails stay put).  Next, weight aloft can be significantly reduced by 1) stripping the covers on the working ends. 2) Due to the increased strength, you may many times be able to reduce the diameter of the new halyard(s), further reducing weight aloft.  NOTE: If downsizing the line diameter, be sure your clutches and winch self-tailers can optimally accommodate the new, smaller size (less surface area to grip).

TIP: Some high tech double braids will have blended cores (polyester or polypropylene blended with Dyneema, Technora or Vectran) to provide improved strength and lower stretch at a lower price.  These are core dependent lines, and require a high tech eye splice, but they will not generally have coated cores, and should not have the covers stripped to save weight.

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