Construction & Properties of Rope

Rope Construction

A rope is made of fibers of a material twisted together to form yarns, which are then twisted together in the opposite direction to form strands. Three strands twisted together again in the opposite direction to form three-strand rope. The directions of fibers, yarns, and strands are continually reversed so the finished product holds shape and provides greater strength. If the initial fibers were twisted to the right, then the rope itself will ultimately be right hand laid, by far the most common. Some ropes are left hand laid. When coiling, always coil in the direction of the lay or it may cause kinking, drastically reducing the strength of the line and making it difficult to coil or otherwise store. Rope is a general term and generally comes on a spool. It is properly referred to as line when it is cut to a specific length to serve an intended purpose.

Small stuff is the term used for twine or small ropes approximately ½ inch in diameter or less. Traditionally this would be pulled apart from older retired lengths of rope and pressed back into service for lashings, decorative knot work, lanyards attaching tools to your person, rope fenders, chafing gear (such as baggywrinkkle when used to protect sails from chafing on rigging), and so on.

Natural Rope Properties

The first ropes were made from natural materials, either constructed of vines or leather. Stands of grass or fibers of plants quickly became the most popular material, namely manila which comes from the abacus plant. It is stronger than hemp, which is also a natural fiber. Natural fiber line will rot if it remains wet and so should only ever be stored dry. It also tends to shrink when wet.

When manila is tarred it is known as marline or ratline, a material typically used for seizing or lashing. Rope is tarred to protect it primarily from absorbing moisture. Because of the tarring process, it is only ever used for standing rigging, not for running rigging which might run the tarred surface through blocks and sheaves.

Synthetic Rope Properties

Synthetic ropes are much stronger than natural fiber ropes of the same diameter. They do not rot from exposure to moisture, but do weaken from exposure to sunlight and subsequent UV damage. Synthetic materials each have different attributes which makes each type more favorable for certain purposes.

Polypropylene floats and is suitable for life rings or boat painters, as these will have less chance of getting caught into a boat’s propeller.

Nylon stretches up to 40% without failing, absorbs shock, and is particularly suited for dock lines but is also used for towing hawsers.

Dacron/Polyester stretches very little and is suitable for rigging where static qualities are desirable such as standing rigging.

Sometimes brand names are used, such as Dacron or Vectran for polyester. There are also other high-strength and expensive synthetic fibers such as Spectra, Dyneema, aramid, Kevlar, or combinations of these are used together for specific desired qualities and some of which are stronger than wire.

One characteristic of synthetics is that they are more slippery than natural fibers. Whereas three tucks are acceptable for natural fiber splices, five or more are required for synthetic ropes. Some knots likewise may be more slippery and require better dressing up to prevent failure.Care of Natural Fiber & Synthetic Line

Whenever lines are being moved, pay particular attention to chafe points. Line may be end-for-ended to freshen up the working end periodically, some vessels will do so on an annual basis. This is a process whereby a line is unrigged then re-rigged starting from the opposite end.

Try to never drag a line over dirt. Doing so traps grit within the line which can cut internal strands. Natural and synthetic line may be gently washed and dried if dirtied.

Uncoiling Line

Rope comes on a spool and is best kept there until needed, at which point the spool should be suspended horizontally and the rope pulled from it. Manila specifically comes like a parcel, and the end of the line should be brought up through the middle of the coil (if it is unwound from the outside, it will invariably kink). This is similar to a process called thoroughfooting which is coiling a line then pulling the bitter end up from the middle; this is done to remove kinks from an already kinked line.

Coiling Line

Lines can be coiled several different ways. A working coil is a line placed in a circle on the deck with subsequent circles laid atop of it. A gasket coil has several turns around the middle of a working coil to enable its transport without spilling and hanging for inventory. A flemish coil is a spiral started on deck with subsequent spirals laid next to the previous, forming a pinwheel (typically starting from the center and working outwards); this enables one to walk on the coil without tripping it, and it is mostly employed on dock lines of yachts. Flaking a coil on deck is laying it down in parallel rows, snaking back and forth, whereas flaking has the ends of each turn overlapping the previous for the purposes of the line running free quickly without fouling.