The U.S. Naval Research Laboratory will not give up the fight against one of the most tenacious and enduring enemies of the maritime force, the barnacles.
For sailors, barnacles are an ancient scourge. Even today, they cost the Navy billions of dollars and continue to pose a thorny problem for scientists.
A sailor scrapes barnacles on a hard-shell inflatable boat aboard the Nimitz-class aircraft carrier USS John C. Stennis (CVN-74).
The barnacle has a strong adsorption capacity, it can not only be attached to the reef, but also attached to the hull, so that it cannot be washed away by the wind and waves. It is one of the marine pollutants with strong adsorption capacity and high attachment density, which is harmful to coastal defense, marine transportation, industry and fishery. For example, when they are attached to the bottom of the boat, the sailing resistance of the boat increases significantly, the speed decreases and the fuel consumption increases. In addition, barnacles also have a serious impact on marine aquaculture. For example, barnacles compete with fish, shrimp, shellfish and other marine organisms for feed, block aquaculture meshes, and seriously affect the growth of marine organisms.
The accumulation of barnacles, mussels and bacteria on the hull of ships is called "biofouling" or "biofouling". Barnacles produce super-tough insoluble adhesives and are the most terrifying biofouling producers. The study found that the presence of barnacles can increase the fuel consumption of ships by 40%. In the 18th century, the British Navy began to wrap the hull with copper skin, making the ships immune to barnacles and ship maggots (ship maggots can cause great damage to wooden ships). Under water, a toxic film forms on the copper skin, preventing any marine animal invasion.
Boat maggots get their name from the fact that they burrow into the wood and wreak havoc on wooden boats. Barnacles, mussels and algae are major sources of biofouling and are looking for a place to settle.They will try to stick to anything, including the bottom of the boat.
Barnacles attached to ships' engines
The Navy wants barnacles to feel "unwelcome," says Kathryn Wahl, a chemist and materials scientist at the Naval Research Laboratory and program officer for coatings and biofouling at the Office of Naval Research. The main problem with barnacles is that they slow down the boat and increase fuel consumption. Even the latest boat or a recently cleaned hull can be affected by biofouling from the moment it enters the water. Unless protected by an antifouling coating, in just two weeks, their presence is enough to cause resistance, and they start to become difficult to remove.
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In just six months, the speed of the guided missile destroyer will be reduced by two knots, unless the bottom of the ship is cleaned, and this This effect grows faster in warmer water. It takes time and resources to scrape them off and keep ships out of force for maintenance and away from their operational duties. That's why the Navy wants to gain the upper hand in the fight against these underwater pests.
During the naval battle between Japan and Russia against Malaysia, the huge Russian Pacific Fleet traveled long distances from Europe and traveled for a long time before reaching the Asian naval battlefield, but the combined Japanese navy fleet waited for it and set up an ambush circle to hit Russia hard. fleet. There were indeed tactical and commanding reasons for the failure of the Russian fleet. However, the Russian sailors were exhausted physically and mentally after traveling for a long time, including a large number of aquatic creatures attached to the hull, which affected the combat speed of the Russian battleship and was also an important reason for the Russian fleet's defeat to the Japanese fleet. The best thing you can do with
is to not let them ship in the first place.Val said of the barnacles: "A large part of their success is due to their ability to attach to different objects by secreting a thin layer of adhesion, which grows and expands as the organism grows and expands. It settles down." Barnacles, like mussels and tubeworms , secrete extremely strong glues that stick together underwater. Mussels can make more than 20 proteins in the glue; scientists have discovered and begun to identify more than 50 proteins in the bonding interface of barnacles. After each molt, the barnacles secrete a ring of sticky proglomerate, which contains many biochemical components and strong adhesive forces that keep them firmly attached to the carrier. The peculiar adhesion of barnacles has drawn attention, and once successfully developed, this "barnacle" adhesive will show great prowess in underwater rescue and leak repair work. But so far, it doesn't seem to have been developed.
Researchers in this lab are studying the chemical composition of this glue , how it is made and how it is applied to surfaces. They are also investigating how the shape and design of the barnacle's shell make it difficult to remove from the surface. The barnacle's shell acts as armor.
Shoveling barnacles requires specialized tools and then protection, barnacles have a very hard shell that can easily scratch people
"We are working to better understand how barnacles attach to surfaces, and through this One point offers new ways to produce alternatives to toxic paints and surface treatments. "Some of our research material shows promise in this area," Wahl said.
She said the Navy has identified some interesting aspects of barnacle bonding On the one hand, these aspects can help develop new strategies to fight dirt.Researchers are trying to develop an antifouling coating that would release barnacles more easily (that just don't stick to them) and prevent them from growing on surfaces without the use of toxins. "Understanding barnacles and their interactions with reactive chemicals in surface treatments is one way we can explore these opportunities," she said. Paul Armistead, program manager for coatings and biofouling at the Office of Naval Research at
, There are two main types of antifouling coatings - ablation coatings and self-polishing coatings. They stop dirt by releasing a toxin. IMO regulations on antifouling coatings have become more stringent. Tributyltin, or TBT, used to be the preferred fungicide , which can effectively prevent the growth of algae, barnacles, and other marine organisms. But TBT also killed other marine life and was subsequently banned internationally. Today, paints to be more friendly to the marine environment.
After the Navy transitioned from wooden ships to stronger steel ships, the presence of copper skin caused steel to corrode faster. In addition to copper-based coatings, other coatings have also been tried, using toxic substances such as arsenic, mercury, strychnine, cyanide, tributyltin, etc. But harmful to other marine life, tributyltin was banned after causing havoc on oyster farms in Europe.
Throughout the late 1970s and 1980s, European oyster juvenile attachment failures were widespread. Lead to huge economic losses in the shellfish industry. It was later found that it was caused by tributyltin.
Self-polishing coatings usually require a steady flow of water on the hull, such as a merchant ship that is sailing most of the time and traveling at a fairly constant speed.
Commercial ships commonly use self-polishing hulls
Navy ships can be docked in ports for several days at a time, or are sailing at high speeds, and the ablative coating can help strip marine life that has already inhabited.The (new) antifouling paint is based on silicone resin . "These aren't self-polishing, and they don't contain biocides. They don't stop dirt, but the surface is very smooth, which makes it difficult for them (referring to barnacles and hulls) to stick to them," Armistead said. The ability of to coat is improving. "With the older antifouling coatings, the barnacles fell off at 20 knots. With the newer, the barnacles fell off at 10 knots per hour," he said.
In addition, the US Navy has announced the development of an underwater robot for cleaning barnacles on the hull. This four-wheeled robot is called "Automatic Hull Bionic Underwater Cleaning System". The U.S. Navy said: “In a way, its mission is similar to household floor-sweeping robots, lawn mowers, or some advanced pool-cleaning robots. In design, this robot does not need a lanyard, has autonomous capabilities and It has a long battery life and uses a battery to complete the task."
Similar cleaning robots are already available for people, and
is used in China and abroad.
