Natural Fibre Ropes - Drying, Coiling, and Storage
Collection: Regenerative Materials | Series: Natural Ropes |
Subject: Why how you handle rope between uses matters as much as how you treat itThe interval is where the damage happens
Most of the deterioration in natural fibre rope does not happen when the rope is working. It happens when the rope is wet and sitting in a locker, or dried badly and coiled too tight, or hung in a damp sail bag at the end of a season and not looked at until spring. The mechanisms of failure — bacterial decay, internal abrasion, salt crystallisation — are all most active when the rope is not being used and not being attended to.
Atkins and Purser noted in their 1936 trials that ropes may become entirely useless while stored below decks, especially in tropical climates. The same process operates in a temperate damp locker, just more slowly. The difference between rope that lasts three seasons and rope that lasts eight is mostly in these intervals — how it was dried, how it was coiled, where it was stored, and whether anyone looked at it properly before putting it away.
Drying
The salt problem is specific and worth understanding clearly. Sodium chloride is hygroscopic — it absorbs water vapour from the air. Once a rope has been wetted by seawater, salt crystals deposit throughout the fibre bundle as the rope dries. Those crystals then continuously draw moisture back from the surrounding air, so the rope is never truly dry unless the salt is removed first. A rope that feels dry to the hand in a boat's cabin may have 20–30% moisture content in its fibre core, which is well above the threshold at which bacterial cellulase activity proceeds.
Freshwater rinsing before drying is therefore not optional maintenance — it is the step that makes drying effective. A thorough rinse with fresh water dissolves the deposited salt from the fibre bundle and allows the rope to reach genuinely low moisture content when dried. Without it, drying is largely cosmetic.
Rinsing. Run fresh water through the rope at moderate pressure — a hose rather than a bucket, so the water penetrates the strand structure rather than running over the surface. Work the rope through your hands as you rinse to open the strands slightly and allow water to reach the interior. For larger diameter rope — anchor rodes, towing warps — coil it loosely and submerge it in a tub of fresh water for thirty minutes before hanging to drain. The salt will diffuse out; the rope will dry properly.
The drying environment. Warm, ventilated, and out of direct sunlight is the target. Direct sunlight accelerates drying but progressively degrades the lignin fraction of the fibre — a point covered in the mechanisms post — and for treated rope it volatilises the lighter fractions of the tar faster than necessary. A shaded, well-ventilated space with air movement is considerably better than direct sun. Below decks with hatches open and adequate through-ventilation is acceptable. A sealed, unventilated locker on a warm day is not drying — it is steaming.
Artificial heat can be used carefully. A heated drying room or a forced-air system will reduce drying time substantially, but temperatures above 50°C will begin to damage fibre structure in prolonged exposure, and above 80°C the situation accelerates sharply. For a boat with shore power, a dehumidifier in the rope locker is a more useful tool than a heater — it removes moisture from the air rather than heating it, which is gentler on the fibre and more effective at achieving low equilibrium moisture content.
How dry is dry enough. For rope that will be treated with linseed or tar before storage, the target is 12–15% moisture content — the same threshold used for timber before oil application. Below this point the fibre will absorb treatment compounds properly rather than having them sit on a surface that is already partially occupied by water. A rope at 15% moisture content feels slightly cool to the touch on a warm day; a rope at ambient equilibrium moisture in a dry heated space is what you are aiming for. The practical test is to coil the rope and hang it in a dry space for a week — if it still feels noticeably cool or damp when handled, it is not ready for treatment or long-term storage.
Minimum drying time. In a temperate British summer, a thoroughly rinsed rope of 20mm diameter hung in a shaded ventilated space will approach acceptable moisture content in three to five days. In wet autumn conditions, two weeks is realistic. In a heated drying room, two to three days for most sizes. Large-diameter rope — 30mm and above — takes considerably longer to dry at the core than the surface suggests. When in doubt, give it more time.
Coiling
Coiling seems straightforward until a rope develops a persistent kink or twist that no amount of working out will resolve, at which point the relationship between coiling method and rope construction becomes abruptly relevant.
Three-strand laid rope is twisted — it has inherent torque built into its structure. The construction post covers the mechanics in detail, but the practical implication for coiling is simple: a right-laid rope — which is almost all three-strand natural rope — must be coiled clockwise. Coiling it anti-clockwise works against the lay, induces torque into the rope structure, and eventually produces hockling — the formation of a loop that flips over on itself when the rope is put under tension, producing a kink that permanently damages the strand geometry at that point. The Handbook of Fibre Rope Technology discusses hockling and snarling as a failure mode specifically associated with over-twisted or badly coiled laid rope, and the damage at a hockle point is structural rather than surface — the rope will fail there preferentially under load.
The Marlinspike Sailor's instruction is direct: "since rope is right laid, it is always coiled right-handed or clockwise." Smith adds that new rope often comes kinked, and the cure is to coil it clockwise and allow it to settle. Trying to remove kinks by stretching or pulling usually makes them worse by inducing further torque.
Flemish coiling. For rope that will be left on deck for display or short-term access — a heaving line ready to throw, a dockline at the bow — the flat spiral Flemish coil is both practical and traditional. Start from the standing end and work outward in a flat spiral, keeping each turn fair and tight against the previous one. The rope lies flat, is free of kinks, and can be paid out cleanly from the outside inward. It is also, incidentally, the traditional way to present a dockline for inspection — any irregularity in the coil reveals an irregularity in the rope.
Hanging storage coils. For rope stored below or hung in a locker, the standard coil with an overhand tie at the top is adequate for short periods. For longer storage, a figure-of-eight coil — passing the working end alternately to each side of the coil rather than in a single direction — distributes the inherent twist in the rope more evenly and reduces the tendency to develop a set in one direction. This is worth doing for any rope that will be stored for more than a few weeks.
Coil diameter. The coil diameter relative to rope diameter matters. A tight coil on large-diameter rope maintains a permanent bend at each turn, which stresses the outer fibres of the strands. As a rough guide, the coil diameter should be at least twenty times the rope diameter — a 20mm rope should not be coiled tighter than a 400mm diameter coil. For storage over a season, larger is better.
After treatment. Rope that has been freshly treated with Stockholm tar or linseed should not be coiled tightly until the treatment has cured sufficiently — the surfaces will stick together under pressure and the coil will be difficult to open without damaging the treatment film. Hang freshly treated rope loosely in open loops for at least forty-eight hours before coiling for storage.
Storage
Ventilation above everything else. The primary requirement for rope storage is air movement. A dry, ventilated space — even an unheated one — is a better storage environment than a warm, sealed one. Bacterial decay is an aerobic process in most of the organisms responsible, and while the bacteria will work in low-oxygen conditions too, the rate is significantly lower with good air movement. The trap on most small boats is the sealed rope locker with limited drainage and no through-ventilation — warm, damp, dark, and stagnant. If the locker smells musty when opened, the rope inside is deteriorating regardless of how well it was dried before storage.
On a boat that is afloat and in use, the practical answer is to ensure the rope locker has ventilation holes that are not blocked, to drain and dry the locker itself at the end of each sailing season, and to inspect rope at the point of storage rather than discovering problems when the rope is next needed.
Away from chemicals. Natural fibre rope is sensitive to acids, alkalis, and organic solvents in ways that synthetic rope is not. Acids hydrolyse cellulose directly — battery acid spilled in a locker containing natural rope will cause immediate and severe damage. Bleach, even in vapour form from a nearby container, attacks cellulose. Fuel and solvent vapour does not damage the fibre directly but will degrade tar and oil treatments by dissolving the lighter fractions. Keep natural rope away from the battery box, fuel tank, and chemical storage.
Separation by type. Treated rope stored in contact with untreated rope will transfer treatment compounds to the untreated rope, which sounds useful but is not — the transfer is uncontrolled, uneven, and may deposit compounds on rope where they are not wanted (cotton decorative rope picking up tar from an adjacent hemp line, for instance). Coil and store rope types separately.
Darkness. UV degradation is a slow mechanism relative to bacterial decay, but there is no reason to accelerate it. A dark locker, or rope stored in a cloth bag rather than a transparent container, is marginally better than rope left on an open deck in sunlight between uses. For rope used in a fixed installation — jacklines, permanent deck lashings — this is where UV exposure accumulates and where periodic retreatment with a surface-coating dressing matters.
Hanging versus coiling flat. Rope stored hanging — over a peg or through the coil — maintains better air circulation than rope coiled on a flat surface. The bottom of a flat coil is in contact with the surface below it, which may be damp, and has restricted airflow. Hanging storage, where the coil can breathe on all sides, is preferable for any rope in longer-term storage.
End of season
The end of a sailing season is the right time to do three things simultaneously: rinse, inspect, and treat.
Rinse while the rope is still wet from the last sail rather than after it has dried salt into the fibre. Hang to dry thoroughly — for a British October this means a heated space or a run of dry weather, not leaving the rope in a shed as the temperature drops. Once dry, inspect along the full length before treating: open the strands at intervals to assess internal fibre condition, check the end treatments for integrity, and replace any rope that shows internal powdering or strand softening. Treating rope that is already significantly degraded is pointless — the treatment cannot restore structural integrity.
Then treat with Stockholm tar or appropriate dressing, allow to cure, and coil for storage. Rope that goes into winter storage in good condition, properly treated and coiled in a ventilated space, will come out in spring in essentially the same condition it went in. Rope that goes into winter storage wet and untreated may be fit only for composting by April.
The composting point is not a throwaway comment. One of the practical advantages of natural fibre rope over synthetic is that rope that has genuinely reached the end of its working life can be cut up and added to the compost heap or dug into the ground. Unlike the synthetic rope and microplastic problem, there is no disposal issue — degraded natural fibre is just organic matter. But that is an argument for composting worn-out rope, not for accelerating the process by neglecting it in storage.
Sources: W.R.G. Atkins and J. Purser, The Preservation of Fibre Ropes for Use in Sea-Water, Journal of the Marine Biological Association of the United Kingdom (1936). H.A. McKenna, J.W.S. Hearle and N. O'Hear, Handbook of Fibre Rope Technology (Woodhead Publishing, 2004). Hervey Garrett Smith, The Marlinspike Sailor (International Marine, 1971).
At VAKA I design and test build skin-on-frame sailing craft in natural materials throughout — the rope that rigs and fends them follows the same maintenance logic as the hull: attend to it between uses, not only when something fails.
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