Ropework

As a reminder, here are a few notes on knots, as explained by Jim Corr. For on-line tuition of rope-work go to Animated Knots by Grog, or click on underlined knot names.

Tools (roll over thumbnail image): ditty bags with tarred nylon twine, serving tool front right, scraper plane bottom and some fids and needles.

Rope in general. Most traditional natural ropes are three strand with a right-hand lay and left twisted strands. Knots are used within a rope, bends tie two ropes/lines together. Remember, every knot weakens the rope significantly!

Sheet Bend. To tie two different size ropes together. Very strong.

Bowline. General tying up. Easy to open, strong if right.

Crown Knot. If you don’t have a thimble, this is just as strong, as each strand takes the force. Finish with splicing the ends.

Figure of Eight Knot. Useful stopper knot.

Constrictor Knot. To hold strands together, very strong and secure knot.

Matthew Walker (photo). Stopper knot within the strands of the rope. Used for dead eyes.

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Lugsail

The use of sail on currachs may have once been more common than it appears to be today. How far back the use of sails dates cannot be established, but two-masted skin boats were certainly in use in medieval times and the Broighter Boat, a gold model generally identified as a skin boat and dating to the 2nd century BC, features a central unstayed mast for a square sail.
In the 20th century currachs in Galway Bay and in Kerry were sailed with a small, reefable 45sqft lugsail, and there is photographic evidence of sailing currachs in Downings Bay, Donegal about 1900. They carried a small dipping lug sail of calico (finished with a bolt rope and sewn cringles) on an unstayed mast, set in a mast shoe and cross beam or thwart. This combination, together with the absence of a ballast keel or centre-board only allows for reaching and running. The far forward position of sails on the currach, unusual for sailing boat design, is sometimes attributed to the historical practice of omitting the centre mast on medieval currachs.

White deal is sufficiently strong and light to serve for both the yard and a slender mast. The small sail is often made of 10-12oz cotton canvas to which light hemp rope is stitched at the edges. As observed by James Hornell in the 1930s, the use of sail on a currach requires the use of one or more steering oars, or a combination of oar and leeboard lashed to a leeward thole pin.

More on lugs’ls on Jim Michalak’s Boat Design. See also our Sails page, which describes the making of a traditional jib and sprit mainsail.

Techniques are explained in The Sailmaker’s Apprentice by Emiliano Marino (1994/2001).

Tanning of Sails

Excerpt from Dixon Kemp, Manual of Yacht and Boat Sailing and Architecture (11th and final edition, 1913):

"No tanning will entirely prevent mildew, if the canvas is left unopened and unaired an unlimited time. For a 20ft. boat boil in a furnace of 15 gallons 28lb. of catechu, until thoroughly dissolved; put in such sails as convenient, and let them soak a night; then spread and mop them over both sides with the mixture. If required very dark indeed, double the amount of catechu Sails too large for a furnace or vat are mopped only on a floor of asphalte, or cement, with the mixture. Sails are sometimes "tanned" in a tan yard with oak bark and ochre. The yarn of the Bembridge Redwings is dyed before it is woven."

How to do it: An amount of oak bark about 1⁄2 the weight of the sail itself is boiled in water and then further diluted. The sail is dipped in this solution and dried without any further need of a mordant given the high tannin content of the oak bark.

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Covering a Currach

The use of tanned hides to cover boats on the Iberian peninsula has been described by the Roman historian Strabo as early as the 2nd century BC. Until the introduction of tarred woven fabric in the early 19th century pelt, semi-cured raw hide and vegetable tanned hide continued to be used as the main covering material for currachs. Hide needs to be smoked, dressed or better still cured in salt and lime to prevent it from deteriorating. On the Brendan, Tim Severin used ox hides that had been tanned for twelve months in a solution of oak bark and then smeared and soaked with hot – and smelly – wool grease. In 2005 the West Clare Currachs club made a replica of a 16ft, 1820s type leather currach, the Tarbh na Mara. Its design was based on a 1822 account by Captain Frazer, a Royal Navy engineer stationed in west Clare at the time. Frazer specified the use of raw hides, dressed with coal tar and pitch – a proofing method still used on contemporary canvas currachs. The replica was covered with four cured hides, stitched and tacked to the gunwales, allowing them to shrink-fit before dressing, a method used on some early currachs. Infrequently used, and stored outside the whole year round, Tarbh na Mara’s skin dried out and as a result the leather gradually shrunk as much as 20%, tearing the seams and ripping away from the gunwale. Working hide boats, in contrast, would have been continually wet and damp from regular use and the hides themselves generally removed in the winter season – the hide was normally lashed to the gunwale to facilitate its removal.

The experiment demonstrated that fabric covers (both home and industrially woven) not only saved on time and initial material cost of the currachs, but also greatly improved maintenance and usability. On the downside, however, canvas is more liable to tear than hide. It is probably for this reason that currachs on the Boyne continued to be covered with hide late into the 20th century, as there was a greater likelihood of hitting sharp stones on the banks and bed of a fast running river. Flax mills were established in Ireland by the late 18th century, and canvas made from linen – and later American cotton – was easily obtained, both new or in the form of packaging such as flour bags. A single layer of 12-16oz cotton canvas is sufficient for most types of currachs. Some Donegal and Mayo currachs, however, were covered with two ‘skins’ of 9-10oz calico, which offers a finer and denser weave. Sometimes an additional layer of brown paper was used to separate them. Due to limitations in the width of the canvas, several runs of canvas may have to be joined for longer boats. This is easiest done inside-out, before turning the canvas over so that the seams eventually lie hidden on the inside of the boat.

For information on tarring go to the Materials page

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