Legislation is changing how we avoid marine fouling;

And that's a good thing! 

The two main objectives of any anti-fouling system are to prevent fouling from occurring on the structures to be protected and to minimize or eliminate any negative effects on the surrounding environment. This is proven by the growing movement to legislate the banning of toxic solutions such as Copper paint, and solutions that destroy the larvae that cause fouling in the first place.

The legislation is being introduced to protect the ocean ecosystems, but it is focused on the most common method of reducing marine fouling. Copper Paint. This will certainly help, however we need to go further and not destroy marine life such as mussels, oysters, coral, pinworms, barnacles etc just because we placed another home in THEIR environment on which to settle. Imagine if we could prevent marine fouling WITHOUT affecting the ocean ecosystem? Well the good news is we can.

EMCS Industries is proud to offer a non-polluting anti-fouling solution that will work from the smallest recreational vessel to the largest cruise ship. It can also be applied to structures in the marine environment that can be difficult to protect with conventional means.

The NOXX™ LFP (formerly Hydrosonic Hull Tender invented in 1974) anti-fouling system is an electronic system that is fitted on the inside of the hull or structure to be protected. The system comprises one or more control panels and a set of emitters operating on 12 volts DC with minimal energy consumption. The control panels can be fitted in any convenient location and all the emitters are fitted on the inboard side of the hull, sea chest, crossover, piping systems, strainers etc.

The equipment can operate continuously to provide ongoing protection. It does not interfere with any electrolysis, marine depth sounders or radio equipment. The system works regardless of the material used on the hull or inboard applications. There is no need to bring the vessel out of the water to install the equipment. The installation of this equipment does not remove pest growth already present. Consequently, once installed the area must be free of fouling at the time of commissioning, thereafter the NOXX™ LFP will keep the treated areas fouling free.

Overview of the Scientific Principles involved  with NOXX LFP

During the development of the system laboratory research was conducted on the effects of low frequency sound on cyprids or barnacle larvae. Initially the larvae are very small and are free-swimming looking for a suitable place to attach. They have to find a landing spot within a limited amount of time of around 2 weeks for their survival.

Groups of cyprids of age 0, 3, 6 and 13 days were tested for an exposed period of 20 hours. For each age group, there was significantly less attachment when exposed to the low frequency sound. The low frequency vibrations discourage them from attaching to the protected surface and encourage them to settle on nearby unprotected surfaces.   

The study also found that low frequency sound causes no apparent harm to barnacle larvae. They are still competent to metamorphose after prolonged exposure to the sound waves. These low frequency sound vibrations cause a behavioral modification in the barnacle larvae such as predator avoidance.   

It was found that high frequencies are ineffective for the prevention of attachment (the test was conducted at Woods Hole Oceanographic Institute using frequencies of 20 - 40 kHz which were ineffective and remained heavily fouled). In addition, high frequencies are used by large sea mammals to communicate and the high frequency had a negative effect on these animals.  

It was determined in the same testing that the low frequency method of antifouling was environmentally benign, and is unlikely to cause any structural damage. Ultrasonic frequencies (14 kHz) by comparison are lethal to barnacle and mussel larvae.   

Their conclusion is that any antifouling device that could reduce the need for anti-fouling paints and lengthen the haul-out times for vessels would be positive for both the environment and costs. Low frequency sound was also shown to be effective to combat potential in fouling situations where other approaches are ineffective, such as inside pipes and cooling systems, and on surfaces that cannot be readily removed from the water.

In summary, it would appear that the sound frequency is similar to the barnacle larvae's natural enemies, which they wish to avoid, so they swim away from the protected surface and find a more suitable unprotected surface for attachment. In addition, the sound vibrations may produce a very slight movement of the microscopic layer of the water against the surface being protected to make attachment more difficult as they test for a good spot to land. 

So, no need to panic, we can achieve marine fouling prevention WITHOUT destroying the ocean ecosystems. The legislation is a good thing.  

Tenille Villebrun