The evolving practices of underwater ship cleaning

Navigating the seas presents a continuous battle against biological fouling, where marine organisms cling to ship hulls, impacting efficiency and maintenance costs. This article delves into the rigorous methods—from underwater divers to cutting-edge technologies—that safeguard vessel performance and environmental sustainability amid these persistent challenges.

Biological Fouling: A Persistent Challenge

The cleaning of ships is a critical aspect of maritime vessel maintenance. During their voyages, sea creatures such as barnacles and worms build up on the submerged part of the ship. This biological fouling or epibiosis is the unwanted accumulation of microorganisms, plants, algae, or small sea creatures on surfaces such as ship hulls, causing degradation to the paint and metal structures. Biological fouling spawns a range of problems, including increasing the weight of the ship and drag, reducing fuel efficiency, and racking up costs while taxing the ship systems with sustained higher loads. It is well known that biofouling is a drag on the shipping industry and our marine ecosystem. The accumulation and growth of algae, marine sessile organisms, barnacles, and mussels adversely affect the operational efficiency of oceangoing vessels. The decrease in vessel speed results in higher fuel consumption and Greenhouse Gas Emissions (GHG). Moreover, the transfer of invasive aquatic species (IAS) into foreign waters poses a major threat to the health of local marine ecosystems. The removal of early stage fouling development, also described as ‘microfouling’, at regular intervals delivers the best results. As the study published in February by researchers for the Frontiers in Marine Science described, this "gentle, habitual and frequent mechanical maintenance of submerged ships' hulls" is crucial to remain free from the effects of biofouling and preserve the expensive anti-fouling coatings.

The Role of Underwater Divers

Underwater divers play a vital role in the rigorous upkeep and cleaning of ship hulls, which helps to maintain vessel efficiency. These professional experts immerse themselves in the maritime depths to address the ongoing issue of biofouling. Their tasks extend below the visible surface, ensuring that the undersea environment is conducive to the vessel's efficient operation despite the frequently demanding and severe conditions beneath the waves. As they expertly perform their delicate tasks in the perilous underwater environment, their efforts extend beyond routine maintenance to safeguard the ship's longevity and functionality. Underwater divers help vessels navigate the oceans more efficiently, ensuring that marine activities function smoothly and continuously.

Dry Dock Dilemma

As previously said, macrofouling happens when these annoying living critters are allowed to thrive and expand, frequently ruining costly anti-fouling hull coatings. This can result in dry docking sessions, which are the last thing an owner wants, as well as additional cleaning and repair chores that are both expensive and time-consuming. Divers are then deployed underwater to clean the massive superstructures and clear them of these parasites; most ships are put into dry dive mode for cleaning, especially during their yearly general maintenance. But the cost of cleaning a ship in a dry dock is extremely costly; a ship in dry dock typically costs between 1.2 and 1.6 million dollars, not including business losses or the weeks it takes to complete the work and get the ship back in service. Because of this, several ship owners have made the decision to use divers equipped with specialized equipment to clean their hulls while they are still in the water in order to prevent these losses. This procedure is included in the category of ship husbandry. Because they must spend lengthy hours working in greasy waters beneath ports and harbors, these divers are unique. They must perform dangerous, alone work beneath the hulls of enormous ships as part of their jobs. There's no way to the surface directly from there, and if the tide suddenly recedes and the ship slumps, a diver might be in grave danger beneath the hull.

Minimizing Environmental Impact

Traditional air tanks are utilized by divers, however fixed hose tanks are also frequently employed. The technology used to clean ships underwater has advanced as well, with most of the cleaning becoming automated and greener. Numerous ship husbandry procedures—a term that encompasses all hull repair, cleaning, and general upkeep—have the potential to discharge hazardous substances into the sea. For example, underwater hull washing can release sizable amounts of copper and zinc. The organisms released during the cleaning process put additional strain on the surrounding ecology, which has a significant negative influence on the environment. However, more ecologically friendly options are now available thanks to advancements in ship technology. Drones that can clean the hull without harming the outside covering or contaminating the water are one example of this. Other cutting-edge technologies are using concentrated water jets as a gentler alternative to brushes and strong scrubbing methods.

Life in the Saturation Chamber

In some situations, hull cleaning may need diving to depths that exceed regular diving restrictions, ushering in the world of saturation divers a completely separate domain. The diver works in a pressurized chamber, which is typically 15 to 20 feet long and constructed to replicate the surrounding environment. The chamber has two bunks on top and two bunks below, with a tiny passage in between. These saturation divers can occasionally stay in this restricted environment for up to 28 days, inhaling a combination of helium and oxygen the entire time. A team of two to three divers completes the task in a mission-like manner; they frequently work in shifts of as long as six hours at a time before going back to the saturation chamber to make room for the next crew.

Going Remote

Using robots to perform ship hull cleaning and other deep-sea tasks is one method to prevent human error and fatalities. The incapacity of humans to exist underwater is eliminated by the employment of remotely operated vehicles, or ROVs. Numerous tools are installed aboard ROVs, which can be operated from the ship's deck or other safe location. There is no need for them to decompress because this remotely operated equipment operates at depths well below human reach. Operators of Remote Operating Vehicles (ROVs) need to possess extensive training to handle such intricate machinery. Additionally, this work is very technical and requires a sufficient grasp The underwater hull cleaning robot can not only clean sea creatures attached to the hull in a convenient, quick, and efficient manner, but it can also provide real-time live image services for border control, classification society inspection, insurance company evidence collection, hull damage inspection and repair, and so on, all under remote control, significantly lowering the cost and risk of underwater inspection.