Obsessing about rope

Scott Bradner

Many years ago, long enough ago that I do not remember who, where, why or when, someone told me that the lower ropes on clipper ships were left twisted whereas the running rope and much of the other rope was right twisted. Since this was long before I was involved in ship modeling, I am puzzled as to what the context might have been for someone to tell me that. In any case, that factoid stuck with me in the background through the years and popped to the foreground when I started work on a model of the Donald McKay clipper ship Flying Cloud and it set me on a quest to find out just what the story was. This article is the result of that quest.

Rope is not a new concept

First of all, rope is far from a new concept. Figure 1 is of a coil of rope made from papyrus fibers from about 3,800 years ago that was found in an Egyptian cave. This rope was likely made for rigging Egyptian river boats. It looks just like the rope we use today.

Figure 1

Sizing rope

For general background, rope on ships was sized by its circumference. Thus, a 4-inch rope is rope that has a 4” circumference (about a 1¼” diameter).

Types of rope

Let’s start out with a review about the types of rope used on ships back in the day (where “the day” was anywhere from 150 years ago to thousands of years ago). For thousands of years rope has basically been plant material twisted into yarns, and those yarns twisted into rope. For most of this time there have been three basic rope designs known (at least in the 1800s) as “hawser-laid,” “cable-laid,” and “shroud-laid.” See figure 2.

Figure 2

All of these types of rope start with fine fibers of plant material such as hemp. These fibers are twisted together into yarns. Multiple yarns, in turn, are then twisted together to produce a strand.

Three strands can be twisted together to produce a hawser-laid rope.

Four strands can be twisted together to produce a shroud-laid rope but when you do that you wind up with a void in the middle of the rope, so you have to fill that void with yet another strand, a strand about half the size of the other strands.

Four-strand rope is a special rope that was used for lanyards and manropes. Four-strand rope is the same as shroud-laid rope without the center strand.

Three or four hawser-laid ropes can be twisted together to produce a cable-laid rope.

Note, that the direction of twist reverses at each stage. So, if you twist the fibers together in a clockwise direction to produce the yarn, you would twist the yarns together in a counterclockwise direction to make a strand and twist the strands together in a clockwise direction to produce a rope. You need to do this so that the tensions in the rope try to hold the rope together rather than just let it unravel. (See, for example, Ashley[1].)

Twists.

According to Herbert R. Carter, the number of twists per foot in a rope is inversely proportional to its circumference and that a 2” diameter rope has 8 twists per foot.[2] This information leads to the following equation:

T = (6.28/C)*8

Where T is the number of twists per foot and C is circumference of the rope. (The value “6.28” comes from the fact that the circumference of a rope that is 2” in diameter is 6.28”). In researching for this article, I purchased sample lengths of many different sizes of hemp rope and measured the number of twists per foot in each of them. I found that the samples closely matched the results of this equation.

I have not been able to make scale rope that has as many twists per scale foot as the equation calls for. The strands break before they have been twisted enough. But I have achieved 70% or so of the value or so for a range of scale rope sizes, and I think the result looks good enough.

The handedness of rope.

Now a word about the handedness of rope. Ropes can have a right or left twist, see figure 3.

Figure 3

Most rope on ships and for other uses has a right twist. The 3,800 year old Egyptian rope in figure 1, has a right twist, as would any non-braded rope you might buy at the hardware store tomorrow. That said, it turns out that some hawser-laid rope used on both warships and clipper ships had a left twist. Cable-laid rope made from normal right-twist hawser rope would be have a left twist. The big question is “what rope was used for what purpose on these ships and why chose that particular rope?”

Running rigging

A lot of the rope on sailing ships was, and is, running rigging that goes through blocks or is used to tie things down and needs to be flexible. Historically, almost all rope used in running rigging on large sailing vessels was hawser-laid rope with a right twist. Apparently, this was because such rope was strong enough and flexible enough to do the job and last a reasonable length of time. I say “apparently” because I have not found any document that specifically says why hawser-laid rope with a right twist was chosen for running rigging, but I did find a few references that said that specific ropes, for example cannon breaching rope[3], and the rope used for the lower and topsail yard braces on clipper ships were hawser-laid rope with a left twist[4] because, it was claimed, such rope was “more pliable and less likely to kink”[5], but was not as durable than hawser-laid rope with a right twist.

Note that most or the ropes in running rigging must be small enough in diameter that the sailors can grasp it to haul on it and wrap it around a belaying pin, that means that the largest practical sized rope for running rigging is about 4.5” (a little less than 1.5” in diameter). Some of the rope in running rigging connects to blocks and is not handled directly so it can be larger.

The fore and main course sail sheets & tacks are another case where hawser-laid rope with a right twist was not used. These ropes were cable-laid lines that were quite large at the sail end and then were tapered along their length so that they were small enough for sailors to handle and secure to a belaying pin at the far end.[6]

Standing rigging

The term “standing rigging” covers shrouds, pendants, stays, backstays, lanyards and guys as well as ratlines, foot ropes, man ropes and stirrups. The yarn to be used in making standing rigging was treated with Stockholm Tar[7] during manufacturing[8] before being twisted into strands so that the resulting rope would be more water resistant and longer lasting. The yarn used to make running rigging was also tarred but to a much lesser amount.[9]

Cable-laid standing rigging

I started this quest to find out what types of rope were used on large sailing vessels because I had been told at some point that the lower rigging on such ships had a left twist where normal rope has a right twist. But neither of the most common reference books on ships rigging (Biddlecombe & Underhill) made any mention of using cable-laid or left twist rope for standing rigging such as shrouds.

At some point I noticed that the shrouds and some of the other standing rigging on some of the ship models in the Boston Museum of Fine Arts and in the U.S. Naval Academy Museum in Annapolis were either left twisted cable-laid rope or at least were rope with a left twist. See the figure below:

Figure 2: Shrouds on models in the U.S. Naval Academy Museum

Specifically, there are 35 models in the U.S. Naval Academy Museum that represent large sailing ships built before the late 1800s and are rigged. The main stays on 32 of them have a left twist and 14 of these stays are clearly cable-laid, and the shrouds on 13 of the 35 models have a left twist and some of these shrouds are clearly cable laid. I was told that many of the models had restoration work done on their rigging at some point, mostly by one particular restorer so if that restorer thought that some standing rigging should have a left twist that could have impacted multiple models. But some of the models, including the St George and one or more of the prisoner models still have their original rigging (the silk rigging on the St. George dates from about 1702!) and these models show cable-laid stays (the St. George and the prisoner models) and/or shrouds (the prisoner models). Thus, it was clear to me that there was something that Biddlecombe and Underhill were not mentioning.

Figure 3: Cable-laid stay on the St George

After quite a bit of searching I located David Steel’s early works, including the first and second editions of the Art of Rigging, Peter Forge’s Tables …, and Brady’s The Kedge-Anchor, all of which detailed the use of cable-laid rope in the standing rigging of large sailing ships. Now I had proof that what I had been told was accurate and had a lot of detail on where cable-laid rope was used. Since then, I located additional references that help fill out additional details.

The research I undertook showed that shrouds, pendants, stays, backstays and guys on large sailing vessels were usually cable-laid.[10] thus, they had a left twist.

For example, the figure below shows a shroud and deadeye from the HMS Invincible which sank in 1758. The rope is cable-laid with a left twist.

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Figure 4: Shroud and deadeye from HMS Invincible

But why would ship builders decide to use cable-laid rope for the shrouds, pendants, stays, backstays and guys on big sailing ships? For very large shrouds and stays the answer is easy, the rope making processes of the day could not reliably make hawser-laid rope larger than 9” in circumference, due to difficulties in keeping yarn tensions even.[11]

But this is a reasonable question for smaller rope. Those contemporaneous documents that discuss the use of cable-laid rope, point out that cable-laid rope is weaker than hawser-laid, but it seems that the mariners of old thought that cable-laid rope was watertight. For example, see this quote from Luce’s 1863 Seamanship:

Cable-laid … Rope, …, is left handed rope of nine strands and is so made to render it impervious to water, but the additional twist necessary to lay it up seems to detract from the strength of the fibre, the strength of plain laid being to that of cable-laid as 8.7 to 6; besides this, it stretches considerably under strain.[12]

It may or not have been the case that cable-laid rope was more “impervious to water” than hawser-laid rope but the fact that it was a widely assumed feature would lead shipbuilders to use cable-laid rope for standing rigging, where they did not want to have to replace it as often as they replaced running rigging rope. The logic seems to have been: if using cable-laid rope kept the water out maybe the rope would rot less and thus last longer.

In any case, cable-laid rope was in common use as late as 1909, as is shown in the following quote from H.R. Carter:

Ropes from 1 to 2 ½ inches in circumference are usually hawser-laid, and from 3 to 10 inches either hawser- or cable-laid. Above 10 inches they are always cable-laid.[13]

The conclusion that most if not all of the shrouds, pendants, stays, backstays and guys on ships like the Flying Cloud were cable-laid is reenforced by the rigging tables in many references that included the types of rope used on sailing ships around the time that the Flying Cloud was active. (See endnote 10.)

As mentioned above, cable-laid rope can be made of 3 or 4 hawser-laid ropes. Duncan McLean wrote that the standing rigging on a number of the Donald McKay clipper ships, built and launched around the time that the Flying Cloud was launched, was made up of “four-stranded patent rope of Russian hemp[14].” I assume McLean meant cable-laid rope made up of 4 hawser-laid ropes, although it is possible that he might have meant shroud-laid rope. I think the letter is unlikely since it would contradict the many references that insist that most standing rigging was cable-laid, particularly since at least the lower shrouds and stays were larger than what could be achieved in hawser-laid rope. In addition, the routing tables for merchant ships in the early editions of Steel’s The Art of Rigging show cabled 4-strand rope for stays, backstays and shrouds.[15]

Lanyards

Lanyards used with deadeyes were made of four-stranded, tarred, hawser-laid rope.[16]

Footropes, manropes, Flemish horses and stirrups

Footropes (old name “horses”) hang below the yards to support sailors working on the sails, footropes are supported by stirrups if they span a wide enough space, Flemish horses are short footropes that overlap the base footropes to reach the ends of the yards, and manropes are strung alongside booms, etc. to provide a handhold.[17] I did not find any references that said what type of rope was used for footropes, stirrups and Flemish horses, so I have assumed that they were tarred hawser-laid roped with a right twist.

Manropes were tarred 4-strand rope like lanyards.[18]

Ratlines

Ratlines were tied across shrouds to enable sailors to reach the yards and upper masts. Ratlines were generally 1 to 1.5 inch rope and thus, too small to be cabled. I did not find any references that said what type of rope was used for ratlines, so I have assumed that they were tarred hawser-laid rope with a right twist.

Worming, parcelling and serving shrouds

Worming is wrapping a small rope into the spiral groves in a large rope to make the rope’s surface smoother. Parcelling is wrapping strips of canvas around a rope in a spiral fashion and tarring the result thus sealing in the worming rope. Serving is tightly winding a small tarred rope around a parcelled rope to create a barrier to chafing such as by sails.[19]

Figure 5: Worming, parcelling and serving a rope

Shrouds are wormed, parcelled and served where they go around a mast.[20] Also, the full length of the foremost shroud of each set of shrouds is wormed, parcelled and served to protect it from the rubbing of the sails.[21]

Sizes of deadeyes, lanyards and blocks

Here is some other rigging-related sizing information I found in my research.

The diameter of a deadeye is 1.5 times the circumference of the shroud or other rope that it will be used with.[22] This matches the information in those rigging tables that include deadeye sizes.

The size of a lanyard in a deadeye is half the size of the shroud or other rope that the deadeye will be used with.[23] This matches the information in those rigging tables that include lanyard sizes.

Blocks are sized based on the size of the rope that will run through them. Specifically, the thickness of the sheave in the block is 1.1 times the diameter of the rope, the diameter of the sheave is 5 times the thickness of the sheave, the slot for the sheave is the thickness of the sheave plus 1/16”, the length of the block is 8 times the width of the sheave slot, the width of the block is 6 times the thickness of the sheave, and the thickness of the block is ½ the length of the block.[24]

Thus, the length of a block (what is often referred to as the size of the block) can be expressed in the following equation:

L = ((D * 1.1) + 1/16) * 8

Where L is block length and D is the rope diameter.

Overall, single blocks are about ¾ as thick as they are long and half as wide as they are long. Double and triple blocks are wider.

For my Flying Cloud model

After all the research, I decided to use natural color hawser-laid rope with a right twist for all of the running rigging except for a few yard braces - which will be natural color hawser-laid rope with a left twist, and the course sheets and the course sheet tacks – which will be natural color tapered cable-laid with a right twist (if I can figure out how to make tapered cable-laid rope).

I also decided to use dark brown/black 4-strand cable-laid rope for the shrouds, stays, backstays and guys; black/brown 4-strand hawser-laid rope for the lanyards, and black/brown 3-strand hawser-laid rope for the rest of the standing rigging, including foot ropes, ratlines, etc.

An earlier version of this article was published in the April 2020 issue of the USSCMSG Broadside.

photo credits:

figure 1: https://www.bu.edu/cas/magazine/fall10/Egypt/index.shtml

figures 2 & 3: photos by author

figure 4: forgotten source related to the HMS Invincible

figure 5: https://www.hmsrichmond.org/knots.htm

6/17/2021