Nanotechnology making yachts greener

21 January 2015 • Written by Richard Boggs
Nanotechnology promises to extend paint life and reduce hull maintenance beyond anything ever before imagined

Nanotechnology is poised to considerably bring down the costs of maintaining and operating superyachts.

‘Nano’ is a derivation of the Greek word for ‘dwarf’. Nanotechnology is the synthesis, design and application of materials as small as a few atoms in length or width. As a measure of size a ‘nano’ refers to a nanometre or one-billionth of a metre. In comparison, a strand of human hair is about 60,000 nanometres in diameter.

While nanomaterials and nanostructures are nothing new. What is new is the technology that allows scientists and engineers to manipulate atoms and molecules, arranging them to produce some remarkable, useful products.

Paints

One of the areas where nanomaterials are generating tremendous interest in the yachting industry is paints and coatings. On microscopic inspection, even the best multi-component finish is a Martian landscape of craters and valleys. Each imperfection of this visually perfect finish is a trap for the natural nanoparticles found in airborne contaminants such as smoke. Water molecules in the air quickly penetrate the finish, and sooner than any owner desires the bill for another million in paint work seems to be due.

But nanotechnology provides a new box of tools that promises to extend paint life and reduce hull maintenance beyond anything ever before imagined.

Because nanoparticles are so small, some scientists consider them as a distinct state of matter with their own unique properties. In the simplest sense, they can function as crack fillers or barrier materials. Fundamentally, the particles each exhibit electrical charge properties that produce an attraction far stronger than the much larger particles that make up standard paints or coatings.

Nanomaterials are generating tremendous interest in the yachting industry as paints and coatings

Nanoparticles can make paint cling to itself and the hull the same way a gecko clings to a window. This unique phenomenon actually makes some coatings “self healing” in that minor physical damage such as scratches or abrasions will use natural forces to restructure the damaged area and restore finish and corrosion resistance.

Confucius said, ‘Be a lotus.’ That advice was based on one of that plant’s most remarkable characteristics – no matter how dirty its surroundings, the first drops of rain wash it immaculately clean. For thousands of years, no one, scientist or philosopher, was able to explain this.

Thanks to the scanning electron microscope, scientists discovered that a lotus leaf (and a butterfly’s wings) maintains its squeaky clean surface by keeping water and dirt at arm’s length. The surface of a lotus leaf is covered with nano-sized water-repellent bumps and a waxy material that prevents moisture from wetting the leaf. Dirt and other contaminants, including bacteria, adhere to the water droplets and are held away from the leaf’s surface.

This phenomenon has tantalized materials scientists, but only recently has nanotechnology provided materials that can duplicate the lotus’s self-cleaning properties.

While truly self-cleaning paints won’t be reducing a deckhand’s workload in the very near future – lotus-like coatings currently available are easily damaged by abrasion, even oily fingerprints – there are easy-to-clean coatings available now.

Rather than holding water and dirt away from the surface, they coat the surface with a layer of nanoparticles that fill all the peaks and valleys found on even the smoothest looking surface. Although not self-cleaning, the water and labour required to remove what little dirt does adhere is greatly reduced compared to standard coatings and they are just as durable.

Nanoparticles can make paint cling to itself and the hull the same way a gecko clings to a window

Antifouling

Conventional antifouling techniques are based primarily on two approaches: paint that contains dispersed particles of organocopper compounds that are poisonous to marine organisms attempting to cling to the yacht’s hull, and non-stick coatings that prevent organisms from gripping the hull’s surface.

Biocidal formulations are being phased out (i.e. the now-banned tributyltin bottom paint) because the compounds used can be lethal to other marine life, even in extremely low concentrations. But because nanoparticles can tightly lock biocidal compounds to their surface, they can be encapsulated within or bound to the surface of the lattice of what are called ‘dendritic nanostructures’.

When these structures are combined with non-stick or slippery antifouling coatings, the biocidal action occurs only when an organism is in direct contact with the tightly bound compound. The release of toxic chemicals to surrounding seawater is virtually eliminated, while highly effective antifouling properties persist for much longer periods than existing systems.

Carbon nanotubes helped reduce the weight of this US Navy sea drone by 75 per cent weight, while improving its structural strength

Construction

This same property of electronic attraction and crack filling used in paint applications make it possible to use nanomaterials to produce nanocomposites with structural qualities that far exceed conventional layups.

Columbus, Ohio-based Zyvex Technologies proved the concept by building an Unmanned Surface Vessel for the US Navy using carbon nanotube-reinforced carbon fibre composite construction.

According to the builder, the 8,400-pound vessel would have weighed more than 40,000 pounds if constructed using conventional fibreglass techniques. This weight reduction alone reduced the fuel consumption from an estimated 50 gallons per hour for the glass version to 12 gallons per hour at 25 knots.

The use of nanotube reinforcement is credited for this 75 per cent weight reduction while also improving the structure’s strength and durability.

The same properties that give nanoparticle-containing coatings “self healing” properties provide nanocomposite materials with remarkable abilities to resist the stress cracking often seen in areas of stress concentrations on conventional fiberglass construction.

On a larger scale, strong electrical bonds between nanoparticles resist potentially damaging cyclic loads. This process effectively counters the forces that otherwise would cause delamination or cracking, and it’s this characteristic that allowed Zyvex to reduce structural weight to such a large degree without sacrificing strength or durability.

Nanotechnology is being used to develop more efficient methods of burning diesel fuel, to reduce pollution from this fossil fuel

Fuel Additives

Among the fast-growing applications of nanotechnology in yachting is the use of metallic oxide fuel additives to reduce production of diesel exhaust soot and to reduce fuel consumption.

A very small amount of cerium oxide nanoparticles is introduced to the fuel where it becomes evenly dispersed. When the fuel is burned, the cerium nanoparticles transport oxygen from oxygen-rich areas of the cylinder to oxygen-poor areas, thereby providing much more complete combustion and greatly reducing soot production and fuel consumption.

Cerion Energy has used this technology to produce its GO2 Diesel Fuel Optimizer. In 2011, it conducted independent third-party testing of the additive on two superyachts and the results are significant.

Big Fish, a 45m expedition-style yacht, showed an 11 per cent improvement in fuel economy and a 20 per cent reduction in soot. Observed on the 62m motor yacht Apogee were a 14 per cent improvement in fuel economy, a nine per cent reduction in soot, and a 20 per cent reduction in greenhouse gas emissions.

Fabric Treatment

Titanium dioxide, the substance that makes white paint bright and adds blocking power to most sunscreens, has another remarkable property: it’s a photocatalyst.

In the presence of moisture and the sun’s ultraviolet light, titanium dioxide nanoparticles catalyse, or break down, some of the water to produce oxygen radicals (oxygen atoms with an extra electron or two), which are very effective in destroying organic materials such as dirt, bacteria, oil and other naturally occurring contaminants.

What this means is deck furniture fabric treated or manufactured with titanium dioxide nanoparticles can’t be stained by sunscreen and won’t transmit odours.

Carbon nanotubes are the strongest and stiffest man-made material yet discovered. But they don’t just come in tubes.

Battery Performance

Although barely on yachting’s radar, nanotechnology in energy production and storage is looming large in terrestrial applications.

The most promising and, to date, practical battery chemistry is lithium-ion polymer technology, whose advantages include very high energy density, low weight, high-power output, fast recharge and discharge without the memory effect.

As good as lithium-ion batteries are, nanotechnology promises to improve their performance exponentially. A good lithium-ion battery can provide around 400 charge/discharge cycles before its capacity drops to about 80 per cent of its maximum capacity.

In a marine application, such as a large yacht which depends on a battery for propulsion and hotel power, that might mean a short and very expensive lifespan. But the performance of a lithium-ion battery depends on the surface area of its plates, and a polymer electrode comprising nano-sized lattices can hold an enormous amount of active material compared to conventional plate materials.

This means that batteries in the near future may be capable of up to 40,000 cycles when the technology developed by Stanford University researchers is commercialised.

As yachts become larger, we can look to the smallest man-made components to provide enormous improvements in efficiency, performance and reduction in maintenance. Future superyachts might be fuelled by natural gas stored in nanoparticle-reinforced tanks, to produce electricity stored in a next-generation battery. And all will be fitted in a hull that slides effortlessly through the water, leaving no toxins in its wake.

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