In accordance with written verdicts of the Korea Maritime Safety Tribunal from 2002 to 2020, 239 accidents of overturning and sinking of domestic fishing vessels occurred. In addition, there were many more fishing vessels that sank and capsized, resulting in causes such as fires, explosions, collisions, contact, and stranding not classified as capsizing and sinking.
Most small fishing boats are operated based on their experiences. They have no safety detection device for water ingress. The quantitative safety verification without stability calculation in sea conditions may almost not be available when accidents occurred.
In this study, a small fishing vessel means a fishing vessel that is less than 24m in length and is not subject to the load line designation and stability regulations by domestic law. The 239 written verdicts on all fishing vessel accidents were included in the research subject, and the results of the study can be broadly applied to relatively large fishing vessels.
The root causes of small fishing vessel accidents on Korea MST written verdict were described qualitatively. These root causes were analyzed based on marine engineering and nautical architects in this study. Through the analysis of all 239 accidents, it was suggested to improve the seaworthiness of fishing vessels currently in operation and newly built fishing vessels.
Domestic and foreign regulations were reviewed, and methods to improve practicality were derived by studying the suitability of the analysis of precedent studies for the prevention of overturning and sinking vessels.
Most of the small fishing vessels sank due to the loss of buoyancy due to the water ingression to one compartment below the deck extending to the entire hull compartment. If the inclination of the vessel might be caused by water on deck, additional water ingression occurred to the engine room entrance and hatches, which did not function as watertight or weather-tightness because of the small freeboard and led to capsizing or sinking.
Small fishing boats do not have ballast tanks with adjustable lateral inclination so that the inclination may be adjusted according to the loading position of consumables, tanks, and fishery gears. Even pulling the net can cause excessive tilt.
When the water on deck(WOD) has flowed into the freeing port, it has the same water level as the sea level and acts as a deck load on the side that increases the tilt. As seawater flows in from the side end of the deck, it was analyzed that as the inclination approaches the critical angle, the inclination by WOD effect is greater than the movement of the deck load and the water in the tank.
Although limited to the circumstantial evidence by ship's staff, as a result of the analysis of all the written verdicts, it was estimated that sinking accidents were less than 2% because of the lack of GM as the initial static stability at departure.
It could be concluded that the root cause is a lack of GZ responding to the WOD phenomenon, and the results of these analyses cannot simply conclude that the root cause is a lack of initial stability GM. GZ should be also considered as one of the fundamental problems.
At the same time, the concept of watertightness and weather-tightness in shipbuilding might not be clear at the construction stage. Even though small fishing vessels operate in controlled weather conditions, watertight compartments and weather-tightness are required basically to ensure the vessel's safety even in calm sea conditions.
In this study, the following solutions, in addition to operator training, were conceptually presented to prevent the sinking and capsizing accidents of small fishing vessels in operation.
1) Buoyancy increase required.
2) Measures to reduce the effect of WOD are needed.
3) Sensing device to check the GM should be provided.
4) Sensing devices of water ingress and WOD should be provided.
5) The departure control of small fishing vessels should be designated as the seaworthiness standard wave height.
6) Institutional improvement to maintain watertight division and weather-tightness is required.