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Preventing line chafe

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What is the issue?
If a fibre line is loaded up and exposed to an edge, or anything rough or sharp, the back-and-forth rubbing motion exerted upon this point will cause the line to chafe in two. All running rigging (ropes leading through various blocks, and to different places of the masts, sails, tacks etc) are subject to chafe, be they halyards, topping lifts, leech-lines, bow-lines, down-haulers or furling lines on roller reefing gear.

Sails themselves cause chafe in light inconsistent airs when they are not setting properly or in light conditions with a lumpy or rolling sea. These situations cause a sail to be pulling well for a few minutes, but when a roll comes through or the wind dies, the drive is knocked out of the sail causing it to slap around uselessly chafing itself and everything in its immediate orbit.

The jib furling line on a roller reefing unit is particularly susceptible to chafe. Although it may appear to be belayed and motionless it is constantly subject to a slight loading-and-unloading back-and-forth movement as the headsail strains and or the vessel bow crests and falls off waves and swells.

Why address this?
Modern running rigging is particularly expensive to replace. Once a line is chaffed, even slightly damaged, it cannot be relied upon to support loads and should be replaced. To exacerbate the issue, and this is particularly the case with halyards chafing on spreaders, the chafe typically happens in the middle of the line. When the damaged line is cut down it is likely to be too short to be redeployed for another useful purpose aboard the vessel.

This does not factor in the inconvenience of an operational failure. On a dark night when you are busy with navigation, beating to windward, with lots of water flying around, and something goes bang, the last thing you want to be doing is recovering from that situation and having to rig a new line.

How to address this?
Carefully route all the running rigging away from chaffing dangers and periodically vigilantly inspect all lines, bow to stern to masthead.

Running rigging
Photo: CC0

There are many likely danger points. Lines near crosstrees on the mast, nicked screw heads, a lumpy weld or fitting on a stanchion or pulpit, radar reflectors, rough corners on anchors, a hard edge on a windlass, mast spreaders for relaxed running backstays spreaders, a foreguy on metal lifelines etc. It is best to go aloft but if this is not convenient you may be able use binoculars from deck level to spot the problems of emerging chafe.

The jib-furling line is worth special attention. The line is typically routed from the bow to the cockpit through a row of small blocks along the guardrail stanchions (or occasionally at deck level). These little blocks tend to get knocked out of position on a working vessel and this causes chafe very quickly. Carefully inspect the line to make certain they are at the correct height to address the furling drum and perfectly aligned in height so that the furling line runs through the middle of each sheave and not along the hard metal edges.

Another area where chafe is practically unavoidable is at the masthead where halyards attach to the headboard shackle over the sheaves. The trick here is to order over-long halyards to allow annual shortenings to remove the worn sections at the top of the mast.

Where issues look likely, reroute the line and where this is not possible insert a chafing guard. Extend the life of your lanyards, slings, hoses, dynamic cable, or other products with this tough, abrasion-resistant nylon sleeve

Chafe guards on fibre lines
Drawing: Tony Gibson

Traditionally sailors have wrapped/tied/sewn a canvas or leather chafe guards around a line where it passes over a roller or through a chock. Heavy protective pieces like this can be difficult to keep in place, even when carefully tied or sewn, and may be too big to feed into a sheave or chock. Avoid using a knot on the line to hold the pipe in place as an overhand knot reduces the line's breaking strain to 60-65% of lines strength, and a Figure of 8 knot will reduce the lines strength by 75-80% - see avoiding knots in lines.

The best system we found to reduce chafe was to slide the closest fitting piece of reinforced PVC hose up the line and fixing it in at the chafing point with a few big stitches - make sure that the hose will feed into the sheave before placing the stitches in.

Reinforced PVC Hose
Photo: Courtesy of LUCOHOSE
Alternatively, where it does not have to go through a sheave or tight chock, a pair of figure-of-eight constrictor knots on either side of the hosepipe served well to fix it in place. We used this approach with our self-steering gear lines. This is a lazy approach but it has the added advantage of allowing the knot to be moved about on the line to adjust the chafe guards position until it was in the perfect location.

A transparent hose pipe chafing guard is invisible at first but in time UV degrades it to an unappealing yellow/brown hue. Nevertheless, it will protect the line for years.

Finally, it's worthwhile to have big, deluxe, oversize blocks wherever possible and particularly so at the masthead. Also a little slack on a line where possible will reduce chafe problems.

Fibre line chafe is a real problem aboard seagoing vessels. However once there is awareness of the issue and the vessel is set up properly with periodic inspections, running rigging will last for years.

With thanks to:
Michael Harpur, Yacht Obsession. Header image with thanks to GLEISTEIN.

Avoiding sheet lines chafe

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