As a pivotal component in modern trawling operations, the trawl door plays an irreplaceable role in ensuring the efficiency and effectiveness of commercial and scientific fishing activities. Essentially, this specialized device serves as the "spreader" of the trawl net, leveraging the hydrodynamic forces generated by the water flow as the fishing vessel moves forward. By converting these fluid forces into horizontal spreading power, it effectively opens the trawl net to a predetermined width, significantly expanding the fishing coverage area and thus enhancing the probability of capturing target species such as fish, shrimp, and krill.
One of the most notable characteristics of trawl doors is the great variability in their weight, which is by no means a fixed parameter. This variation is primarily determined by three core factors: model design, manufacturing materials, and the specific fishing scenarios they are tailored for. Generally, their weight ranges from more than 100 kilograms to several tons, reflecting the diverse demands of different fishing operations across the globe.
In terms of materials, traditional trawl doors were often crafted from solid steel to ensure sufficient weight and structural stability. However, with the advancement of material science, modern trawl doors now adopt a variety of composite materials, such as high-strength alloy steel, reinforced fiberglass, and even lightweight yet durable carbon fiber composites. These materials not only adjust the overall weight but also improve corrosion resistance-an essential property for equipment operating in saltwater environments for extended periods-and reduce energy consumption by optimizing the weight-to-strength ratio.
The fishing scenario is another decisive factor influencing the weight of trawl doors. For inshore small-scale fishing vessels, which operate in shallow waters with relatively gentle currents, trawl doors typically weigh between 100 to 300 kilograms. These lightweight models are easy to hoist, deploy, and retrieve, adapting to the limited deck space and lifting capacity of small boats. In contrast, medium-sized ocean-going fishing boats, which work in mid-depth waters with more complex currents, require trawl doors weighing 300 kilograms to 2 tons. The increased weight ensures that the trawl net remains stably spread even when encountering variable hydrodynamic conditions.
For large-scale deep-sea fishing fleets or specialized operations in extreme environments (such as the cold, turbulent waters of the Antarctic), super-large trawl doors are indispensable. Their weight can exceed 2 tons, with some customized models reaching up to 6 tons. This substantial weight provides the necessary downward force and stability to counteract strong deep-sea currents, ensuring that the massive trawl nets maintain their operational shape and fishing range in harsh conditions. Whether for small-scale coastal fishing or large-scale deep-sea resource exploitation, the weight of the trawl door is always a carefully calibrated parameter, balancing functionality, efficiency, and operational feasibility.
Small trawling boards are mostly suitable for small nearshore fishing vessels, and their weight is usually concentrated in the range of 100 to 300 kilograms. Lightweight trawling boards are convenient for small fishing boats to load, unload and control, and are suitable for small-scale fishing operations in shallow sea areas. Fishermen can fine-tune the weight according to different current conditions in the near sea to enhance operational flexibility.
Medium-sized trawling boards are widely used on medium and large-sized ocean-going fishing vessels, with a wide weight range, generally from 300 kilograms to 2,000 kilograms. The trawboard is larger in area and heavier, ensuring stable trawling in medium-depth waters. It is suitable for medium-scale commercial fishing and meets the operational requirements of medium-sized fishing vessels of different tonnages.
Super-large trawlers are mainly used in large distant-water fishing fleets or special fishing scenarios. Their weight can exceed 2,000 kilograms, and the maximum can even reach 6,000 kilograms. A typical 14.2-square-meter trawl board weighs 4,500 to 5,000 kilograms. Its extremely large weight and area can ensure sufficient support for giant trawls in deep-sea strong current environments, enabling large-scale fishing. There are also some 15.0-square-meter trawling boards that weigh up to 4,727 kilograms in the air. Even when affected by buoyancy in seawater, they can maintain a stable posture by their own weight, making them suitable for large-scale deep-sea trawling operations. They can withstand harsh sea conditions by their own weight and ensure the continuous operation of fishing.