Monofilaments & Rigging for Spearguns

Nylon and fluorocarbon monofilaments for spearguns, available in different diameters and formats. High abrasion resistance and maximum reliability for shaft rigging.

Monofilaments and Rigging for Spearguns

Monofilament is one of the essential elements in rigging a speargun. It connects the shaft to the reel or to the speargun muzzle, absorbs the dynamic loads generated by a fleeing fish, and often works in direct contact with reefs, rocks, and abrasive substrates. For this reason, its mechanical characteristics – tensile strength and abrasion tolerance – have a direct impact on the reliability of the entire capture system.

In this category, Deep Blue offers a selection of nylon and fluorocarbon monofilaments specifically geared toward spearfishing and freedive spearfishing, with products covering a range of operating scenarios: from coastal hunting with mid-size spearguns to use on large pelagic fish in open water. Alongside the monofilament selection are stainless steel cables, sleeves (copper crimps), and sleeve crimping pliers, the accessories needed to properly complete the rigging of the shooting line. Available formats include by-the-meter sales, 20-meter coils, and 50, 100, and 200-meter spools, meeting both quick replacement needs and the ongoing rigging of multiple spearguns.

Types of products available

Nylon (polyamide)

Nylon is historically the most widely used material for spearfishing monofilaments. It offers a good balance of tensile strength, flexibility, and shock absorption. In water, nylon absorbs a percentage of moisture that slightly changes its softness. Rob Allen Black Nylon, 2.0 mm diameter with a declared breaking strength of 180 kg, is one of the most widely used monofilaments in the global spearfishing community. The black color reduces the line’s visibility in the water. It is available by the meter, in 100 and 200-meter spools, making it suitable both for simple replacement and intensive rigging.

Fluorocarbon (PVDF)

Fluorocarbon is made from polyvinylidene fluoride (PVDF), a polymer with a light refractive index very close to that of water. This physical-chemical property makes the line visually almost invisible underwater, unlike nylon, which remains visible to fish even in clear water. In addition to low visibility, fluorocarbon has a higher density than nylon, giving it greater abrasion resistance on hard and sharp substrates, as well as substantially lower hygroscopicity, which stabilizes its mechanical characteristics both in water and when dry. Asso Invisible Big Game is offered in two diameters (1.30 and 2.00 mm) on 20-meter coils, in a soft PVDF formulation that maintains good knot strength while keeping breaking loads at high pound-test levels. It is recommended whenever abrasion resistance is a key requirement.

Multi-formulation nylon lines

The Asso range includes differentiated formulations to meet specific operating needs. Asso Tripla Forza is available in Sport Fishing Line and Professional Line versions: both cover a range of 8 diameter and strength variants, with the Professional Line sold by the meter. Asso Doppia Forza Ultrasoft is a 7-variant formulation characterized by greater softness. Asso Classic Clear, available in 3 variants, is the standard clear nylon option for general use.

Stainless steel cables

Stainless steel cable is an alternative to nylon monofilament when building a shooting line. Compared with nylon, stainless steel offers significantly higher abrasion resistance on rocky and challenging bottoms, along with substantial non-stretch performance that transfers pull to the shaft more directly. Deep Blue offers three stainless steel cable references, all with multi-strand construction that ensures flexibility while maintaining high mechanical strength. The 7×19 Stainless Steel Cable is available by the meter in a convenient format for exact replacement. The 7×19 Special Stainless Steel Cable is available in 2 variants. The 7×7 Stainless Steel Cable is available in 2 variants. The 7×19 designation indicates a structure of 7 strands with 19 wires each, offering greater flexibility than the 7×7 construction (7 strands of 7 wires), which is stiffer and suitable where flexibility is less critical.

Sleeves and sleeve crimping pliers

Sleeves (also called crimps) are small metal ferrules into which the monofilament (or stainless steel cable) is inserted. The sleeves are compressed with dedicated pliers to create a connection loop directly on the monofilament itself or on the stainless steel cable. They are the most widely used fastening method in spearfishing for connecting the shooting line to the shaft, the reel line, or the speargun muzzle, replacing traditional knots. A sleeve joint, when correctly made with the proper pliers, provides a stable mechanical hold that does not loosen under repeated tension. Deep Blue offers copper sleeves in the silver version in 7 diameter variants, covering the most common monofilament and stainless steel cable diameters. Rob Allen offers its own specific 2 mm sleeves for use with Black Nylon. Sigal Sub and Salvimar complete the selection with sleeves in 2 variants. For sleeve application, the range includes specific sleeve crimping pliers, both professional tools for a correct, uniform, and secure crimp.

Line Tensioner Shock Absorbers, clips, and Swivels

The line tensioner Shock Absorbers are elastic elements placed between the line connected to the shaft (the shooting line) and the speargun muzzle, or the line coming from the reel, with the purpose of absorbing the jerk generated when the line reaches the end of its travel, or to cushion the run of a struck fish. Without this component, the stresses can lead to faster breakage of the nylon or shooting line, resulting in loss of the shaft. The shock absorber also makes it possible to keep the shooting line connected to the shaft tight and neatly arranged, positioning it precisely between the muzzle and the speargun line release.

Swivels are rotating connectors placed between two elements of the line, usually between the shooting line and the reel line, to eliminate accumulated rotational tension. A line and monofilament subjected to repeated twisting can weaken or tangle. The swivel allows each section to rotate freely without transferring torque to the next section. Deep Blue offers Heavy Duty Swivels in 4 variants; only the small-diameter ones (max 6 mm) are suitable as a connecting ring between the shooting line and the monofilament attached to the shaft. Larger-diameter swivels (between 7 and 9 mm) are better suited for heavy-duty bluewater hunting applications. Some swivels are equipped with quick-release clips used for fast line connection, without the need for knots or crimps.

How to choose materials for speargun rigging

Choosing the correct components depends on several technical factors that should be considered together.

Diameter and breaking strength

Diameter directly determines breaking strength and line bulk, and therefore shaft performance. A low-diameter monofilament allows the shaft to travel faster; a larger-diameter monofilament will slow the shaft’s travel. For small and medium-size spearguns used on medium-size coastal fish, a 1.30 mm diameter offers adequate strength with limited bulk. For bluewater spearguns or bluewater hunting on large pelagics, a 2.0 mm diameter in nylon or fluorocarbon with breaking loads in the 150–180 kg range is the established standard. Rob Allen Black Nylon at 2.0 mm with a declared breaking strength of 180 kg is a benchmark in this segment. The Asso Fishing Lines range also includes models with breaking strengths above 200 kg, placing it among the monofilaments intended for large fish.

Monofilament or stainless steel cable

Nylon (or fluorocarbon) monofilament is the most common choice for shooting lines thanks to its light weight, ease of handling, and availability in a wide range of diameters. Stainless steel cable is preferred in contexts where abrasion is very intense - coral bottoms, sharp rocks, particularly cutting substrates, and high shark presence - where monofilament would be subject to rapid wear or immediate breakage.

Monofilament material: nylon or fluorocarbon

Nylon, thanks to its flexibility and good elasticity, effectively absorbs peak loads and performs well in situations where manual line handling is frequent. Fluorocarbon, due to its high abrasion resistance, is preferable in situations where the line runs close to rocks or sharp substrates. The choice therefore depends on the hunting environment (rocky bottom vs. open water) and the type of fish.

Purchase format

Those who need to periodically replace worn line on individual spearguns will find by-the-meter sales practical, available on several Asso products, on Rob Allen Black Nylon, and on Deep Blue 7×19 Stainless Steel Cable. Those who rig multiple spearguns or manage continuous activity will find 50, 100, or 200-meter spools convenient. The 20-meter coils of Asso Invisible Big Game are calibrated for specific use, where a few meters meet the typical rigging requirements.

Materials and technical characteristics

The nylon (polyamide) used by Asso and Rob Allen is a thermoplastic material with good mechanical strength, moderate longitudinal elasticity, and compatibility with the marine environment. Nylon’s hygroscopicity causes a slight variation in stiffness between dry and wet line: after immersion, nylon tends to become softer and easier to handle when tying knots. Rob Allen Black Nylon has a nominal diameter of 2.0 mm with a declared breaking strength of 180 kg, a parameter that places it in the monofilament category for large fish.

The PVDF fluorocarbon of Asso Invisible Big Game has physical characteristics that clearly distinguish it from nylon. The refractive index of PVDF is very close to that of water, which drastically reduces its underwater visibility. Its higher density than nylon translates into greater abrasion resistance per unit of cross-section, an important characteristic when the line works over rocky bottoms or irregular surfaces. Asso Invisible Big Game is available in 1.30 mm and 2.00 mm diameters on 20-meter coils, with a PVDF formulation described as soft to facilitate knot holding while maintaining high breaking loads.

The Doppia Forza Ultrasoft and Tripla Forza formulations in the Asso range respectively indicate different reinforcement levels of the base polymer and different softness of the finished line. The Ultrasoft version reduces the line’s tendency to retain memory, making it easier to manage during rigging. Tripla Forza, available in 8 diameter variants in the Sport and Professional versions, covers a broad range of breaking strengths to adapt to different speargun sizes and types of fish.

Deep Blue stainless steel cables are made from multi-strand stainless steel. The 7×19 construction consists of 7 strands, each made up of 19 individual wires, resulting in a more flexible cable suitable for shooting lines and rigging where the cable must bend around the loop. The 7×7 construction consists of 7 strands of 7 wires, with a stiffer, more compact structure suitable for short sections or applications where flexibility is less important. Both stainless steel constructions offer significantly higher corrosion resistance in the marine environment than common steel.

The sleeves available in this category are copper ferrules (in the Deep Blue silver version, in 7 diameter variants) and specific versions for 2 mm monofilament (Rob Allen and Sigal Sub). Copper is an easily deformable material that, once crimped with the pliers, permanently maintains the deformation without elastic springback, ensuring a reliable hold over time. Sleeve crimping pliers are the essential tool that allows the necessary compression force to be applied in a controlled and uniform way, preventing irregular deformations that could weaken the joint.

Practical use

Monofilament is used in spearfishing mainly to connect the shaft to the speargun muzzle or to the reel line. It is referred to as the Shooting Line. In some cases, it can be used in the reel in place of the traditional line.

Monofilament – or stainless steel cable – is secured using copper or aluminum sleeves, also called crimps. These are ferrules that, when compressed with the dedicated pliers, allow a connection loop to be created on the monofilament or cable. The loop is formed directly on the shaft fin (or through the hole) of the shaft.

For bluewater hunting, where fish reach much larger sizes and higher speeds than in coastal spearfishing, the line must provide high breaking strengths and resistance to repeated dynamic stress. In these contexts, diameters of 2.0 mm or larger are commonly used, in nylon or fluorocarbon depending on the hunter’s preference and environmental conditions. In situations with particularly abrasive bottoms, stainless steel cable can be chosen instead.

Available brands

Asso is a manufacturer specialized in fishing lines that covers the entire monofilament range with different formulations: Classic Clear, Doppia Forza Ultrasoft, Tripla Forza Sport Fishing Line, Tripla Forza Professional Line, and Invisible Big Game in PVDF fluorocarbon. The variety of versions and the number of variants per line make this range particularly comprehensive for spearfishing.

Rob Allen is a South African brand historically associated with professional and competitive spearfishing. The 2.0 mm Black Nylon is one of the most recognizable monofilaments in the industry, available by the meter or in spools. Rob Allen also offers specific 2 mm sleeves matched to its monofilament.

Deep Blue completes the offering with three stainless steel cable references in 7×19 and 7×7 constructions, available by the meter or in pre-measured variants, and with silver copper sleeves in 7 diameter variants, suitable for covering the most common monofilament and stainless steel cable sizes found in this category.

Sigal Sub offers monofilament sleeves in 2 variants, completing the availability of crimping ferrules for the most common diameters in spearfishing.

The sleeve crimping pliers are professional tools for the correct application of crimping ferrules.

Conclusion

The selection of monofilaments and accessories for speargun rigging available at Deep Blue covers the two key technical materials - nylon and fluorocarbon - along with stainless steel cables in 7×7 and 7×19 constructions, and all the accessories needed to complete the shooting line: line tensioner Shock Absorbers, clips, Swivels, copper sleeves in multiple diameter variants, and professional sleeve crimping pliers.