This month Lizzy looks at the use of ropes on board.
High-performance yachts and dinghies use rope cores made from various aramid fibres – Dyneema, Vectran and PBO (Zylon) – for halyards, sheets, running and standing rigging. These fibres are very strong with minimal stretch, maintaining sail and rig settings over a wide range of wind speeds and sea states.
Dyneema is the most commonly used aramid fibre as it is very strong and light with low creep and has good UV resistance. It is available in four blends: SK78, SK99, SK38 and DM20.
SK78 and SK99 are the two most commonly used for halyards, strops, lashings, purchase systems and backstays.
SK38 is the stretchiest and cheapest Dyneema available, and is best suited as a general purpose core for sailors looking to upgrade from polyester ropes. On the other end of the scale, DM20 dyneema is the firmest on the market with zero creep, and is ideally suited for use as standing rigging and steering lines. Dyneema must always be covered in ‘hot spot’ areas such as turning blocks and halyard sheaves, as it has a low resistance to heat.
Vectran offers the best creep performance of any synthetic fibre and is more heat resistant than Dyneema. It can be used for halyards, steering systems and strops but must be covered with a protective coating as it is extremely susceptible to UV light.
PBO (Zylon) has unrivalled strength to diameter performance and can be used to replace stainless steel rigging. Care must be taken to professionally maintain PBO as it is very susceptible to UV degradation.
The right cover
Covers are added to a rope’s core to increase abrasion resistance, load holding capacity, winch easing and handling comfort. Covers are typically made from polyester and blended with either Technora, PBO or Vectran. Other options include a PBO/Technora blend, Dyneema/polypropylene blend and Dyneema/Technora blend.
Technora blends are the best choice for sheets and inshore racing halyards; they have a good heat/abrasion resistance with a great grip to winch easing balance.
PBO blends are ideal for high load and high temperature applications such as runners, gennaker sheets and high load mainsheets.
Vectran blends are typically favoured by single-handed sailors as they have good winch easing properties and great general use, while Dyneema blends produce lighter rope covers which soak up less water; ideal for lightweight sheets and halyards.
Alongside being able to choose the blend of the rope’s cover, you can also pick between 12, 24, 32 or 48 plait rope. A 12 plait rope will be very flexible and easy to splice, while a 48 plait rope will be stiff with an outstanding resistance to abrasion, making it a good choice as a chafe cover.
If you decide to leave certain ropes uncovered for weight saving reasons, consider protecting them with an appropriate coating such as Polyurethane emulsion (increases abrasion resistance), silicon (reduces friction), hydrophobic coatings (reduces water uptake) or a tacky self-healing coating (improves core-cover adhesion, reduces particle ingress).
Uncovered ropes are smaller in diameter than covered ropes and can be held in place by ‘constrictors’ rather than clutches and cleats, offering further weight saving advantages.
On board you should always store your ropes in a figure of eight fashion to avoid kinks and twists, while soaking ropes in fresh water after sailing will help to remove abrasive salt crystals.
Storing ropes away from grit, dirt, sunlight and water will prolong the fibres of the rope. Finally, always check your deck gear is compatible with the diameter of your new rope.
This year Lizzy is one of six sailors selected to train on board Whitecap’s Artemis 60 as part of the Vendee2020Project. Lizzy is also racing with Team Jolokia, a french team based in France, onboard a Volvo 60.