Last season took its toll on one end of a mooring line on Jean-du-Sud. A repair was in order. I took advantage of the repair to make a short video on how to repair it. I show how to tie a backsplice and a crown knot. I’ll show you how to do it below, but first I’ll give you some basic vocabulary and a brief overview of the different types of mooring lines.
Vocabulary
A mooring line is a rope used to tie (“moor”) a boat to the dock. It’s a rope that’s an assembly of several parts braided together. (Fr.: amarre).
A strand is a rope of smaller diameter used to form a mooring line. A strand may itself be made up of smaller ropes. (Fr.: toron).
Braiding is the technique of joining strands together to make a mooring line. For example, “three-strand braiding” or “eight-strand braiding” may refer to the number of strands in a specific mooring line. (fr.: tresser).
The core of a mooring line is the braided part that gives it its longitudinal strength. (Fr.: coeur).
The cover is the protective part covering the core. (Fr.: gaine)
A splice refers to both the braiding technique and the resulting part on the mooring line. A backsplice is used to finish the end of a mooring line, while an eyesplice is used to make a loop at the end of a mooring line (Fr.: épissure/épissure renversée/épissure en oeil).
To situate this text, I show below how to make a backsplice on a three-strand manila line. (Fr.: une épissure renversée sur une amarre de manille à trois torons.)
Three materials
There are three types of mooring line materials, which can generally be classified in terms of strength. The least resistant are organic lines (hemp or manila), followed by polypropylene lines (which have the great advantage of floating) and finally nylon lines (“modern” lines), which are the most resistant of all. The table below summarizes the advantages and disadvantages of each type of mooring line. On recent boats, the most common mooring line is nylon. On Jean-du-Sud, mooring lines are made of manila. Having not purchased a mooring line recently, we may want to verify the table’s assertions about prices.
| Material | Advantage | Disadvantage | Note |
| Shackle, hemp or other organic material | Less expensive (?) | – Less longitudinal strength. – Does not float. – Will rot if left wet. | Organic mooring lines generally have no sheath. Core is directly exposed. |
| Polypropylene. | – Better longitudinal strength. – Floats. – Does not rot. | – More expensive (?) – More rigid. | Ideal for amooring line, or for a lifeline because it floats. Core exposed (no sheath). Often three-stranded. |
| Nylon | – Maximum strength. – Does not float. – Will not rot. – Flexible. | – More expensive. – Core is easily damaged if exposed. | Nylon mooring lines are covered with a protective sheath. They resemble climbing ropes. |
Splices
Splicing techniques are the same on organic and polypropylene ropes. This is largely because they have no cover, and because these lines generally have a three-strand braid. Jean-du-Sud mooring lines are manila lines, so the technique below applies to both types.
Nylon mooring lines, on the other hand, are covered and generally have a multi-strand core (10, 15 or more strands). Consequently, the technique for repairing nylon lines is not the same. This may be illustrated in a later revision of this text.
Preparations
You’ll need a knife, binding wire or duct-tape. The first step is to remove the unsalvageable part of the mooring line.
In the video above, I show the line in its end-of-season condition. The three strands are clearly visible, as are the strands that make up each strand.
The video shows two single knots tied along the line, a makeshift (and somewhat lazy) repair to prevent further damage. About two feet of the mooring line is sufficiently undone to cut this segment (photos below).
It’s not necessary to cut off the entire section that is no longer braided. If the strands are in good condition, you may want to keep some of them to avoid losing too much length. The important thing is that, once folded on itself, you should have about 15 to 20 times the diameter of the mooring line in length (photo below). As I’m working with a rope about a centimetre in diameter, I’ve reserved 20 centimetres for myself, i.e. 10 centimetres on the distressed part and another 10 centimetres on the correctly braided part.
If the mooring line is new, you’ll want to unbraid the first 10 centimetres. This is an opportunity to overbraid each strand or, if you’re not sure, to cover the ends of the strands with “duct-tape”. The idea is to offer a minimum of protection to the strands, preventing them from unravelling during handling.
The crown knot
The crown knot is used to reverse the braiding direction of the strands. This is the first step in the backsplice. When the splice is complete, the crown knot is the beginning of the mooring line.
The idea is to pass the three strands through each other so that they interlock (image above). The steps are as follows:
- The three strands of the mooring rope are laid out separately. Take the center strand and fold it towards you to form a loop. There should now be one strand on the left of the loop and one strand on the right, forming a “Y”. (Photo 1 below)
- Take the left-hand strand and pass it over the loop you’ve just formed, so that its end is between the loop and the right-hand strand (Photo 2 below).
- Take the right-hand strand and pass it inside the center loop. (Photo 3 below)
- Pull the three strands in succession, so that the knot crushes on the part of the mooring line that is not damaged.
- Finally, each strand should now be turned in the direction of the mooring line, each separated by an angle of about 120° (Photo 4 below).
Splicing: braiding into the mooring line
Once the crown knot has been completed, it’s time to start braiding the strands into the mooring line itself. The idea is to take an unbraided strand and first pass it over one (and only one!) braided strand, then open the mooring line (photo 5) to pass it between two braided strands (photo 6). The video, further down in this text, gives a better view and complements the photos.
What’s next? Repeat! We take the next strand and do the same operation, taking care to pass it through the next opening. Once all three strands have passed through, each should enter and exit at a different point on the braided rope. If two strands come out in the same place, one of them has gone through the wrong place.
Each strand requires three or four successive braiding passes through the mooring line. The recommended minimum for organic lines is three. For more slippery synthetic lines (poly or nylon), the minimum is four. Once the number of passes has been completed, the finished product should look like the photo below.
Cut off (and overbond) the excess
Once the splice is complete, it’s time to get rid of any excess strands. There are two ways of doing this. The first is to cut the strands. The second is to cut and overbind them. The second finish (overbinding) is cleaner, but will cause the strands to protrude a little more, which can be annoying during handling at dockside cleats. The first takes up less space, but leaves the strands open and ragged. In both cases, you’ll want to leave at least one mooring line diameter in excess length. That way, if the splice “works”, it won’t unravel.
As I didn’t have any overbinding wire, I simply cut off the excess. The finished splice is shown in the photo below.
The complete video
The video below describes the entire procedure. Note that it takes seven minutes. So repairing a splice is not a particularly time-consuming task.
Anyone listening to the video carefully will notice that at one point, I passed two strands through the same opening. That was a mistake! So I had to remove the extra strand and pass it on to the next opening. Try to identify this error in the video and pay attention to how to correct it. It’s a good way to learn how to correct yourself if something similar happens to you.
Conclusion
In the world of three-strand mooring lines, the backsplice is the easiest. Other, more difficult splices rely on the same techniques as this splice, but add steps and complexity (e.g. making an eye at the end of the mooring line). In addition to splices at the end of a mooring line, there are also splices to repair mooring lines in the middle.
Then there are splices on more modern mooring lines (nylon, sheathed) which require additional tools and knowledge. The technique is different, and if you want to learn it, you have to be prepared to buy twenty meters of rope, which you’re willing to sacrifice for the purpose of practice. It’s harder!
The content of this page is not particularly original. There are several other online sources explaining how to splice and repair mooring lines. It’s known marine knowledge. If you haven’t fully understood the explanations on this page, I encourage you to dig a little deeper. Below, I refer you to two complementary videos showing the same techniques.
Finally, I’d like to point out that the technique for splicing onto polypropylene mooring lines is exactly the same as that described on this page. The only difference is that polypropylene is generally molded in its braided form. It is therefore very hard to open. As a result, more force is required to open the braid and feed the strands through.
Did you like this text? You can read more in the learn section of this site.
Acknowledgements
My thanks go to A. Lionais and L. Wallace, from whom I learned these techniques.
