Leave no trace: Nine eco updates to make to your yacht today

As yachts travel to more remote – and pristine – parts of the world than ever before, Kate Lardy outlines the differing ways you can reduce your impact on the fragile marine environment.

When Jimmy White, EYOS Expeditions’ newly instated manager of technical, science and conservation projects, says “Yachts have the best access to the most pristine places on the planet,” he doesn’t use the word “best” lightly. 

“The superyacht industry now has better assets than every research and university institute on the planet,” he explains. “The US Antarctic Program, the Australian Antarctic Program, Antarctica New Zealand – any one individual yacht owner has better access to the Poles than those three programmes combined.”

With this kind of unrestrained access comes great responsibility to make the least impact possible on delicate ecosystems. There are many things yachts can do to tread more lightly. From retrofitting cutting-edge systems to using the right interior cleaning products, here are nine changes you can make now to leave behind a cleaner wake.

1. Antifouling

The part of every yacht that touches seawater more than anything else on board – the antifouling – is typically toxic. The most commonly used formulas today contain copper. While effective, copper is a biocide, toxic to aquatic organisms, and it leaches into the water.

Better products have emerged. “When it comes to environmentally friendly antifouling paint, we’re seeing paint manufacturers getting creative, offering silicone-based paints, copper- and metal-free based paints,” says Tim Cooper, director of business development for Marine Group Boat Works, a superyacht refit yard in San Diego Bay. 

“A few brands for recreational vessels that are eco-friendly are Pettit Hydrocoat ECO and Sea Hawk Smart Solution, which are both metal-free. The more popular brand among superyachts that we’ve serviced has been Micron CF, Interlux’s copper-free based paint,” he adds.

“Products made for the commercial segment are slightly ahead of the curve. For example, popular among passenger vessel customers is Intersleek, a silicone-based antifouling paint manufactured by International,” Cooper says.

The 78-metre Piriou explorer Yersin was built like a passenger vessel and chose slippery silicone for its non-toxic qualities. “The silicone is fantastic because you don’t have anything attaching to the hull,” says her captain, Jean Dumarais. “You don’t have any pollutants and biocide, and nothing in the life cycle of this antifouling will be diluted in the seawater for the time you use the boat.” It works best when the yacht is under way, but he reports that even after sitting, they dive under the boat and use a sponge to simply wipe the hull. “It’s not a big deal,” he says.

The commercial market is also the origin of Ecospeed, a recent choice of Vripack’s for two Doggersbank explorers. “It’s completely non-toxic,” the design studio’s co-creative director Marnix Hoekstra says. “The interesting thing about this antifouling is that they’ve chosen the route to go so enormously hard that actually nothing can stick on it because it’s just too tough and too hard.” The product has been proven to last for more than a decade with no decrease in antifouling capability.

2. Drinking water

Plastic is the bane of the sea. The Ocean Conservancy estimates 11 million tonnes of it end up in the ocean every year. As trash management for most islands involves landfill sites that lie precariously close to coastlines, yachts travelling to these regions must first reduce the amount of plastic they carry on board. The biggest and most easily remedied offender is water bottles.

For one, bottled water isn’t all it’s cracked up to be. The US non-profit Environmental Working Group tested 10 major brands in 2008, and found “a surprising array of chemical contaminants in every bottled water brand analysed” – and concluded that purity could not be trusted.

What can be trusted is a watermaker linked to a double-pass system, an all-in-one combo unit made by various companies such as SpotZero that turns seawater into freshwater and then turns that freshwater into ultra-pure water. This needs to go into clean tanks on board, then through a post-tank UV steriliser and carbon filter, and the yacht will have water that far surpasses bottle quality.

Kiyra Staples, founder of the consultancy The Green Stewardess, has some recommendations. “Octo Marine has been a reliable partner who offers the full-circle approach and will test your yacht’s tank water, recommend a suitable system and follow up regularly,” she says. “AquaTru is an example of a filtration system that remineralises water and its sleek fittings and dispersing unit offers the full range of boiling water, chilled ambient water and chilled carbonated water at the touch of a button.”

3. Black water

On the opposite side of the spectrum from drinking water is black water, or waste water. MARPOL (the International Convention for the Prevention of Pollution from Ships) sets certain standards for treated sewage discharge that take into account the fact that contaminants will be diluted in a large ocean.

For the owners of the 60-metre Royal Huisman Sarissa, this wasn’t good enough. The 2024 World Superyacht Awards Sailing Yacht of the Year is fitted with an ACT2 water reclamation system, which, in a nutshell, can make black water so clean you can drink it. Invented by a NASA engineer and the former captain of Limitless, Craig Tafoya, the groundbreaking system has spread through the superyacht world mainly by word of mouth and is now fitted on 22 new-build or refit projects.

On Sarissa, they don’t actually drink their treated waste water; the yacht’s unit treats both grey and black water using a combination of settling, aeration, enzyme digestion and ultra-fine filtration for clear, odour-free effluent that far exceeds MARPOL standards. But if they added a nano filter, the product water would indeed be fit for consumption. The system notably converts 100 per cent of the waste solids into water, leaving behind zero sludge.

“We have found it to be excellent in use over the past year of operation,” says Peter Weller, Sarissa’s chief engineer. “It’s fast and efficient in its continuous processing of waste water. We produce a lot of waste water for the size of vessel and use their smallest WRS8 plant, which can process eight tonnes per day. By comparison we would have had to install three Hamann sewage treatment plants to process the same volume of liquids, which would attract higher initial costs and service maintenance costs, and I’m confident that the end product is better.”

4. Cleaning products

There’s a caveat with the ACT2 system: to keep the biological enzymes alive, all cleaning and bathroom products must be  100 per cent biodegradable and also non-toxic.

“If bleach were used, for example, then the bio enzyme mass would die off and require restarting,” Weller says. “This, however, is a straightforward process, which we have had to do on a few occasions. It takes a little bit of crew education at the start, and monitoring of products in use. Fortunately there is an ever increasing selection of plant-based products available. Sarissa currently uses Botanical Origin products in the interior and Ecoworks Marine products in the engine room.”

Regardless of the black water treatment system in place, using natural products on board is always a good thing. “Eco-friendly cleaning products are a simple yet effective way to reduce harmful chemicals entering the ocean,” says Staples.

A new option for yachts is Washdown, invented by a former superyacht deckhand and chemical engineer. Formulated for both interior and exterior use, the probiotic bio-tech formulas are free of VOCs and pollutants. Most come in concentrated form that can be diluted to make 50 bottles of 750ml, drastically reducing plastic waste.

5. Grey water

Nearly a million tonnes of the plastic that ends up in the sea each year are microplastics, according to the Marine Conservation Society, and the biggest source of these is textiles. The European Environment Agency estimates that globally up to 35 per cent of it comes from the washing of textiles made from synthetic (plastic) fibres.

“Most people are looking into fossil fuels and how to reduce that, which is massively important,” Hoekstra says. “However, all the time they are at anchor they allow the generators to run and washing machines to pump over grey water, etc, which actually harms the local environment maybe even more than emissions.”

Vripack is looking into installing PlanetCare’s microfibre filters on their yachts. “I’m actually testing this in my house,” Hoekstra says. “It’s a super simple device, just a static application of filtering microplastics that allows us to filter all the water from washing machines and grey water tanks. So we’re preventing microplastics [from entering] the water.”

The firm is also looking to install a system that filters grey water to reuse it as technical water for wash-downs on Project Zero, the fossil-fuel-free 69-metre sailing yacht in build at Vitters.

Anticipating a future in which all run-off is prohibited in pristine locations, Feadship plans to develop actively switched scuppers to direct wash-down water into holding tanks. “This is our agenda in the near future,” says Bram Jongepier, senior specialist at Studio De Voogt.

6. Sunscreen

One might not think a bottle of lotion could have much of an impact on the great big ocean, but unfortunately it does. Sunscreens that absorb rather than block the sun’s rays contain a host of unpronounceable chemicals that have been proven to be a serious threat to coral reefs and marine organisms at large.

Oxybenzone is one of the worst. In 2015, a team of international scientists that studied reefs in Hawaii, the US Virgin Islands and Israel concluded that “the chemical not only kills the coral, it causes DNA damage in adults and deforms the DNA in coral in the larval stage, making it unlikely they can develop properly”. They found it present in high concentrations at the most tourist-ridden reefs, and at these same concentrations in lab tests it killed cells from seven species of coral.

Since then, sunscreens containing oxybenzone and another endocrine disruptor, octinoxate, have been banned in a handful of locations around the world, including Palau, Hawaii and parts of Mexico – and they shouldn’t be on board any yacht going near a coral reef. Mineral sunscreens containing zinc oxide and non-nano titanium dioxide are safer. Staples at The Green Stewardess recommends Suntribe, Bare Republic, Coola and Sun Bum. Or wear rash guards and use nothing in the water.

7. Dynamic positioning

Feadship’s fleet research has determined that yachts tend to spend about a third of their time at anchor. Dynamic positioning (DP) is an alternative that guarantees no damage to the sea floor, as a computer holds the boat’s position using the propulsion and thrusters.

It’s tried-and-true tech, in use for roughly  50 years in the offshore industry, and found more and more frequently on yachts in recent years.  For instance, Jongepier says that many Feadships are fitted with DP systems, ranging from heading control when anchored (to prevent fishtailing, which minimises sea bed damage) to station-keeping in light to moderate conditions. 

“The latter is a powerful solution made possible by the full electric architecture of propulsion with azimuthing thrusters and suitable for use in locations where anchoring is prohibited, with the former a more [energy-]efficient solution if anchoring is permitted,” he says.

“We often use our DP system on board Savannah, holding us in position in conditions up to 25 knots,” says the 83-metre Feadship’s captain, Chris Durham. “It has been particularly useful when cruising in remote locations. In 2020 we were lucky enough to spend three weeks in Belize, a country which has a particularly sensitive marine system and one of largest barrier reefs in the world. We operated in DP for days at a time, allowing the guests to explore some of the most pristine underwater environments with minimal impact.”

8. Generator exhausts

Exhaust stains on a white hull and floating bits of soot and oil slicks behind yachts are far too common sights – and one you don’t want in the planet’s most unspoiled waters.

The better builders install diesel particulate filters (DPF) on generator exhaust outlets that capture 95 to 99 per cent of soot, but this only works when the generator load is high and the exhaust is hot enough for the catalyst to burn off the soot. And yacht generators are often oversized and under-loaded, so the filters clog.

SeaClean by EnerYacht is an active DPF system that works continuously to capture soot, eliminating virtually all of the black carbon and hydrocarbon emissions from the generator exhaust, says company founder Richard Boggs, a USCG-licensed chief engineer unlimited and the former technical superintendent of Camper & Nicholsons.

“The reason I invented SeaClean was because boats were getting thrown out of marinas for causing water pollution,” he says. The system uses electrical heaters in the exhaust stream to heat up the exhaust when the generator is running at a low load, so the filters are continuously regenerating, with the catalyst reducing toxic soot particles to water vapour and carbon dioxide. 

“It makes sure that it’s always hot enough that the catalyst kicks off and burns the captured soot. And that gives a very, very long operating life for the filters without having to be cleaned. It’s totally automatic. The engineers don’t have to do anything,” Boggs says.

Mate Nick Cullen on 41-metre CaryAli can attest to that; not only has it been low maintenance, “what you can see coming out the sides of the boat is the cleanest that I’ve seen on any boat”, he says.

9. Rubbish management

Managing garbage on board hinges on having enough storage space to outlast any voyage away from harbour facilities, says Jongepier at Studio De Voogt. Compactors for plastic and cardboard, glass and tin crushers, and garbage freezers are ideal. “Only the largest yachts use [electric] incinerators to further compact solid waste,” he adds. 

Sarissa also has a food digester, which uses biological enzymes to break down and digest up to 10 kilograms of food waste every day. “It turns waste food of most types [no bones, shells, coconut husk or pineapple tops] into water,” says engineer Weller. “There is also a galley grease and fat trap that holds oily substances through gravitational separation, preventing them from leaving the vessel into the sea. We collect this waste manually and dispose of it correctly ashore.”

First published in the September 2024 issue of BOAT International. Get this magazine sent straight to your door, or subscribe and never miss an issue.