Mechanically propelled spears for freshwater fishing

Mechanically propelled spears for freshwater fishing are common in Central- and Northern parts of Thailand. Due to the fact that many people are crafting these devices themselves, there is a wide variety of principles, styles, and designs. Besides of homemade spearguns, where every piece is unique, there is also semi-industrial manufacturing in place. Some individuals are producing lots of e.g.: ten spearguns and are selling them locally and on the internet.

Technological stages of mechanically propelled spears

The simplest spears for fishing consist of a rubber band, which is held by hand and propels an iron rod forward. Such device was presented at one of my earlier articles, see here.

Next technological step forward is a small length of pipe, which got at its backside a rubber band attached. This pipe can be conveniently held in hand, when the spear through the pipe gets drawn backwards with the rubber band and will subsequently be released.

A next step of improvement is the device as mentioned before, but with a pistol grip attached. Which also could be called ‘Slingshot speargun’. This way, aiming and releasing the arrow can be done in a more natural kinematics of the human hand. And further devices can be added, like laser pointer and/or a reel with a closed spool for the line.

Spearguns in the sense of the word

Further improvement is a stabilization of the holding device. Up to now this ‘holding device’ was the human hand stretched forward and creating a counterforce to the tension of the rubber bands. By introducing a stock – like a rifle has got – the counterforce to the rubber bands will be consistently moved into the humans shoulder. There is no moving wrist, forearm, elbow, or shoulder joint any more, but only one stable piece of wood.

Due to this stable holding device, it is not necessary any more to tension the rubber bands for shooting the arrow immediately before release. The rubber bands can now be tensioned long before actual shooting and kept in this place. Spearguns with stock therefore need a mechanism for safely holding and releasing the rubber bands. Which is incorporated as part of a trigger mechanism similar as rifles got.

The action of a certain set of rubber bands can either be increased by additional rubber bands or bow-like limbs for attachment of the rubber strings at the front. These limbs can either have the shape of longbows or recurve bows. Additionally, fishing reels or spool-holding devices will be added to these long-shooting spearguns. Such a speargun will be described in detail at my next article.

This is nowadays the most technological advanced stage of homemade spearguns for freshwater fishing in Thailand. Roller spearguns, using pulleys to increase the force of the rubber bands are up to now only used for speargun fishing in the sea.

Target fish species

In Thailand, it safely can be stated, that every permanent water body is deeming with fish and shrimps. Therefore, there is a wide variety of fish species serving as potential targets for fishing with spears. A study in the UK showed – see here –  that fish with a length of below 30 cm got a very low mass and water resistance and therefore arrows will not penetrate but deflect from them.

This may be the case for classic application of spearguns in the sea, where the spear is shoot through water. But it does not correspond to the practical application of freshwater fishing with spearguns. Here, the spear is shot through the air and only hits fish swimming on the water surface broadside. The remaining energy is by far higher compared to underwater.

Therefore, two general types and shapes of fish will be targeted in Thailand:

1. Flat-bodied species of minimum 20 cm / 8’’ length. That’s in most cases outside of fish ponds: Pla Nin (Oreochromis niloticus, Black Tilapia, Thai: ปลานิล) and Pla Ta-phian (Barbonymus spp., Silver barb, Thai: ตะเพียน)

• At least double as long, cylindrical body shaped fish species. Preferably Pla Sawai (Pangasius hypothalamus, Striped catfish, Thai: ปลาสวาย).

Locations for fishing

Spearguns for freshwater fishing are always used from a location outside the water. That means from a place elevated over the water surface, where the shooting distances are between 5 to 15 meters.

Preferred locations to position oneself are:

• Bridges,
• Elevated pipeline channels over water,
• Platforms of bridge pillar foundations standing in water,
• Dam walls,
• Sluice gates,
• Elevated riverbanks free of vegetation
• …. and such similar places

Speargun fishing is also very popular in Thailand during floods, which regularly occur along the Chao Praya River from the northern parts of Bangkok to Ayutthaya and further up north. During floods there are many more locations available for fishing. And the water during floods is often shallow, where it is easier to spot fish. Another advantage of floods (for fishing) is the fact, that murky water forces some fish to get to the surface for breathing additional oxygen.

Lessons learned about fishing with mechanically propelled spears in Thailand:

• Simplest method of using a mechanically propelled spear for freshwater fishing is just a spear with and rubber band.
• Further improvements are a sleeve for guiding the spear and a pistol grip for easier holding and aiming.
• For such slingshot spearguns, the addition of a reel and laser pointer can be beneficial.
• Next step of improvement is the attachment for all these single devices on to a stock, who takes over the forces of the tensioned rubber bands.