In the world of spearfishing, attention is often focused on the more “visible” aspects, such as the choice of gun, shaft, or rubber bands. However, there is a component that is as discreet as it is crucial and, all too often, underestimated: the system of shooting lines, monofilaments, and knots that complete the gun’s rigging.

It is precisely in these seemingly secondary elements that a significant part of the equipment’s effectiveness and reliability is determined. The quality of the materials, proper sizing, the choice of the most suitable knot, and above all, the care with which every connection is made can mean the difference between a perfect shot and the loss of an important fish.

I often see even highly experienced spearfishermen, with decades of sea experience behind them, making significant mistakes in this area. Choices that appear routine, made out of habit or tradition, but which from a technical standpoint are ineffective or even counterproductive. This demonstrates how often the subject is underestimated or approached without any real updating of knowledge.

What made the difference in my own journey was my strong passion for rod fishing. This broader perspective allowed me to develop a particular sensitivity in selecting monofilaments, braided lines, and knots, transferring concepts and solutions from the angling world into spearfishing. This cross-disciplinary approach proves extremely useful, especially when discussing strength, reliability, and material performance under stress.

When targeting large fish, taking shots at the limits of effective range, or dealing with demanding situations, every detail becomes crucial. A slightly worn shooting line, an inadequate monofilament, or a poorly tied knot can fail at the decisive moment. Conversely, a well-designed and carefully maintained system guarantees not only greater security, but also better accuracy, quietness, and reliability during the shot.

This article aims to provide an in-depth analysis of all aspects related to speargun rigging, with particular attention to shooting lines, monofilaments, and knots. We will examine technical choices, materials, and the most effective solutions in detail, providing practical tools for those who wish to take their equipment—and their performance—to the next level.

To begin, let’s start with what is probably the most important component of the entire system: the section of line that directly connects the shaft to the gun or reel. This is the true critical point of the entire rigging. It is the element that works under the most extreme conditions, subjected to sudden loads, high tension, friction, and abrasion throughout all stages of the shot and, most importantly, during the fight with the fish. It is not just a connection, but a vital link upon which the success of the action depends.

For this reason, every choice related to this section—material, diameter, length, knot type, and connection method—must be made with the utmost care. Even a small mistake is almost always paid for at the worst possible moment: when the fish has been hit and starts to pull hard.

Over the years, I have seen perfectly rigged equipment fail precisely at this point, because of a detail that seemed insignificant but was actually decisive. That is why it makes sense to start here: because more than anything else, the security of the shot and the real possibility of landing the fish depend on it.

Let’s start with the material used for this section. In the vast majority of cases, the choice falls on nylon monofilament, and for good reason. Nylon remains, and has for many years, the best compromise between strength, elasticity, practicality, and cost. It offers excellent load resistance relative to its diameter, good abrasion resistance, and, above all, a slight elasticity that performs a fundamental function: absorbing part of the load peaks generated during the shot and the first stages of the fight. This shock-absorbing ability significantly reduces the risk of sudden breakages, particularly when dealing with large fish.

Another aspect that should not be underestimated is its relative stiffness compared to other materials. Nylon tends to maintain good linearity, runs smoothly through the gun’s line routing, and reduces the risk of tangles or interference during the shot. It is also easy to crimp and allows for clean, reliable, and repeatable terminal connections.

That said, there are valid alternatives that have become increasingly popular among more advanced spearfishermen in recent years. One of these is high-strength monofilament such as Climax, highly appreciated for its exceptional breaking strain and superior manufacturing quality compared to traditional nylon. It offers consistent performance and excellent wear resistance, making it particularly suitable for demanding conditions.

With the same breaking strength, Climax allows the use of thinner diameters than traditional nylon. On paper, this is an advantage. In reality, however, it often translates into a line that is more “cutting” on a fish shot through the belly, less noticeable to the touch, and, above all, more difficult to control by hand—especially in critical situations such as retrieving a large fish or extracting one from a hole, for example a big grouper. In these moments, grip and sensitivity are essential, and a monofilament that is too thin and slippery can become a real limitation.

Another significant drawback is its greater softness. Compared to traditional nylon, Climax tends to be more flexible and less structured. As a result, it is more prone to tangles, especially if the utmost attention is not paid when laying out the shooting line on the gun. The problem becomes even more pronounced aboard an inflatable boat, when the line is left loose during unloading or while handling a fish that has taken line from the reel. In these situations, its tendency to tangle and form unwanted knots is significantly higher.

In my opinion, these characteristics make it less forgiving than traditional nylon. It requires more attention, better organization, and leaves less room for error. All factors that can be managed under ideal conditions, but which in real-world spearfishing—where haste, adrenaline, and less-than-perfect conditions are the norm—can make a significant difference.

For these reasons, my choice remains firmly focused on traditional nylon. Specifically, I use a dedicated black nylon sold by Cressi in 500-meter spools.

At this point, it is essential to understand what characteristics a good monofilament must possess to be truly effective. The first parameter I consider is diameter. Personally, I always use nylon of at least 1.60 mm and avoid going below this size. The reason is often misunderstood. It is not so much about breaking strength under ideal, straight-line conditions, since smaller diameters can also provide very high theoretical values. The real critical factor is abrasion resistance.

In real spearfishing conditions, monofilament constantly comes into contact with rocks, holes, gill plates, teeth, and irregular surfaces. This is where true reliability is determined. A larger diameter provides a more robust cross-section that better withstands abrasion, cuts, and localized wear, drastically reducing the risk of sudden failure during the most delicate moments of the fight.

For this reason, choosing a nylon with a more generous diameter significantly increases overall reliability, far beyond what simple stated breaking-strength figures might suggest.

In light of these considerations, I do not recommend using excessively thin nylon, such as 1.20 mm. In real-world situations, this diameter often proves inadequate during demanding fights, where the risk of failure increases considerably, especially in the presence of abrasion against rocks or sudden loads.

The key point is that the supposed performance advantage—based on the idea that a thinner line makes the shaft faster due to reduced drag—is largely overrated. Practical testing demonstrates this clearly. Tests conducted on targets at distances of 4 to 5 meters using 100 cm double-band guns and the same shaft show that average shaft speed remains virtually unchanged when moving from 1.2 mm to 1.6 mm nylon.

This highlights a fundamental aspect: the friction generated by the monofilament during the shot has far less impact than many people believe. During the initial phase, the shaft is accelerated by the bands with such force that the difference in resistance between relatively similar diameters becomes negligible. Furthermore, until the shooting line is fully extended, its contribution to hydrodynamic drag remains limited.

The effect of nylon diameter only becomes somewhat more relevant during the final phase of the shot, once the bands have finished accelerating the shaft and the line comes fully under tension. However, at normal operating distances and with modest diameter differences, this impact remains marginal and difficult to perceive in practice.

Considering all this, the use of thinner nylon is not justified. The performance gain is negligible, while the loss in reliability is very real. In other words, actual security is sacrificed for a theoretical advantage that does not translate into a noticeable improvement in shooting performance.

Let’s now move to another crucial aspect: connecting the nylon to the shaft. Here there are no shortcuts. It is essential to use correctly sized crimps and compress them exclusively with the proper crimping tool. This method preserves virtually 100% of the line’s breaking strength, something that no knot, regardless of how well tied, can guarantee.

Knots always create stress concentration points that reduce line strength and represent potential failure points, especially under heavy or dynamic loads.

Over time, I have seen many improvised solutions: crimps hammered flat, unsuitable pliers, and poorly executed compression. All of these significantly compromise the nylon’s strength and increase the risk of failure at the worst possible moment.

It is important to make a distinction, however. This recommendation applies particularly to traditional nylon. In the case of materials such as Climax, which are thinner and more slippery, knots can be a valid solution if tied correctly, precisely because of the material’s different characteristics.

Another fundamental and often overlooked aspect concerns all the points where the nylon passes through the shaft: holes, shark fins, and line bridges. It is essential to ensure that these areas are perfectly smooth and free from burrs or manufacturing residues. Even the slightest imperfection can create localized abrasion that gradually weakens the line under load until it ultimately fails.

Ultimately, a proper connection depends not only on the use of suitable crimps and tools but also on meticulous attention to every detail. It is in these often invisible details that the true reliability of the entire system is determined.

Let’s now discuss the reel line, another fundamental component that is often treated superficially. Unlike the section directly connecting the shaft, slightly different requirements come into play here: reel capacity, smooth line flow, fight management, and overall safety.

Regarding material, the choice almost always falls on high-strength braided lines such as Dyneema, for a very simple reason: they offer extremely high breaking strength with exceptionally small diameters. This allows an adequate amount of line to be loaded even onto compact reels without compromising safety.

The key parameter therefore becomes thickness. Here as well, practical experience outweighs theoretical numbers: avoid diameters that are too thin. Extremely fine Dyneema may increase reel capacity, but it becomes difficult to handle during retrieval, tends to cut into your hands under load, and is more prone to tangles or uneven layering on the spool.

Personally, I prefer a diameter that provides a good balance between strength and handling, always prioritizing practicality during the fight. A slightly thicker line offers better control, is easier to grip, and reduces the risk of problems when a fish takes line aggressively. In my opinion, 1.5 mm represents the best compromise.

Now let’s move on to the connection between the shaft nylon and the reel’s Dyneema line, another critical point that deserves attention but not unnecessary complication.

I almost always avoid using swivels or snap clips. It is true that they can reduce line memory caused by weeks of use, but in my case this advantage is irrelevant. After several days of intensive fishing or a demanding fight, I replace the nylon anyway because it may have become abraded and damaged. Any material that remains in the water accumulates stress and microscopic abrasions that are not always visible, and I prefer prevention over shortcuts.

If you choose to use swivels, it is essential to oversize them relative to the expected loads. Anything inserted between nylon and Dyneema becomes a potential failure point, even because of subtle issues such as oxidation or imperfections invisible to the naked eye.

The solution I prefer is simple and effective: a clinch knot with a locking loop. This connection offers excellent holding power, makes the most of the nylon’s characteristics, and, most importantly, can be untied quickly if it becomes necessary to remove the shaft from a fish without additional tools or complications.

In this way, reliability, operational simplicity, and rapid intervention are combined without introducing unnecessary weak points into the system.

To conclude, I cannot help but share an experience that all of us know well: I have lost count of how many times I have seen someone lose an important fish because a component of their equipment failed.

I can assure you that a system like the one described here, built carefully with properly sized crimps, suitable nylon, and well-executed knots, possesses enormous breaking strength and incredible abrasion resistance. Even when the prey is among the largest fish we can encounter in our waters, I can guarantee that it is far easier to be dragged hundreds of meters through the water than to break a correctly made connection.

Ultimately, paying attention to every detail is not merely a matter of technique or precision—it is the best way to transform experience and passion into safety and success. When everything is done correctly, the difference between a lost fish and a successful catch is not a matter of luck but of informed choices regarding materials, diameters, and connections.

The final message is therefore clear: investing time and care in your equipment always pays off, because at sea, sometimes it is precisely those small details that determine the outcome.