Why the sailing yacht movement is greener than ever

16 March 2021· Marilyn Mower

There are few more eco-friendly ways to travel than by sailing yacht, but, thanks to fresh innovations, the future is ever greener. Marilyn Mower investigates.

If you want to go around the world, the only way to do it with any conscience is on a sailing boat,” asserts Wally Yachts CEO Luca Bassani. Indeed, environmental sensitivity and mounting scientific and social pressure for reducing fossil-fuel consumption seemed to be making progress until Covid-19 took over the news cycle. Interestingly, naval architects, designers yacht builders and suppliers have continued nose to the grindstone in anticipation of a future that is not a bounce back but a bounce forward toward a day when far more yachts are powered by sail, and those yachts make an ever smaller environmental impact.

Rather than a green revolution, the actual picture is incremental, “a steady drip, drip, drip,” as naval architect Bill Tripp puts it. “Progress is an S-shaped curve slowly moving up but then something comes along and the axis shifts and it steepens quickly. That’s what happened with electric cars. It was a very long, low curve, but now you can argue that one of the best cars in the world is electric.” 

The Wally 145 has a hybrid propulsion system
Credit: Wally

Is the totally electric boat a possibility? Definitely for a small boat or yachts that primarily day sail, says Tripp, but a superyacht with its high hotel load is a different matter with a lot of variables. Let’s take a look at the puzzle pieces emerging for the development of low-to-no impact superyachts.

A good sailing boat is an efficient boat, but “efficient” can mean either faster or less costly to operate, both attractive outcomes but for different reasons and perhaps to different customers.

At yacht builder Southern Wind, the mantra is “Improving sustainability through efficiency.” Taking weight out is an everyday battle but the yard attracts customers who like the large but pared-down ethos of its boats and their modest crew requirements.

Credit: Southern Wind Yachts

“One of the complaints about sailing boats during Med cruising season is that the wind is too light and the boat won’t go anywhere in less than six to eight knots of breeze unless it’s motoring. We put our effort into resolving that issue,” says Southern Wind commercial director Andrea Micheli. “If a boat has a bigger sailplan, it can sail faster and at a lower wind speed. Our new 105 will carry 15 per cent more sail area than our 102-footer [31-metre]. It will sail in four knots true wind! We will go upwind at 4.5 knots and downwind at 4.9 knots. At seven to eight knots of wind, we sail beautifully at eight to nine knots while most of our competitors will be motoring.”

Of course, sail area is not the only string to the yard’s bow. Boats consume remarkably little energy when sailing; it is the time at anchor with owners and guests aboard when the hotel loads explode. Even a blue-water cruiser sits for about eight months of the year. Southern Wind has invested in the development of awnings that can generate seven to 20kW of electricity using solar cloth panels that stow in a dedicated deck locker.

Credit: Bill Dixon Yacht Design

“When the owner and guests are gone, we think the boat can be nearly energy self-sufficient when on a mooring or at a dock,” says Micheli. “It also keeps the boats cooler during the day. You won’t need to supplement as much with a generator or shore power.”

“This summer we delivered Kauris IV, which has huge battery banks,” says Bassani. “You can motor at 10 knots for eight hours if you don’t have wind. Unfortunately, available solar cells for recharging a yacht of this size are not enough. You can keep a stationary 40-footer [12-metre] charged on solar, but not a superyacht.”

Efficiency also means power management systems and using battery power for peak shaving (upsizing battery banks to draw power off them for silent running or short-term loads) instead of upsizing gensets. “Based on our real data, the 105 will have two 19kW gensets,” says Micheli. One can power the boat and charge the batteries while the other manages short-term demands or hydraulics for sail hoists. Small gensets will run at 70 to 80 per cent load, which is much better for them. Proprietary software lets crew manage energy generation and use.”

The heights of hybrid

Royal Huisman, which pioneered hybrid power with Ethereal in 2009, has an ongoing complete hybrid re-power of its 43.5-metre Juliet to give it the ability to cruise zero-emissions zones. The centrepiece is a new gearbox aligned with a sophisticated electric motor/generator for indirect electric propulsion from the battery bank for silent operation, or a generator via the power management system. The main engine can still turn the prop shaft if necessary or provide electric power to meet the hotel load.

Naval architect Merfyn Owen says that on 25- to 35-metre yachts the main power consumers are air conditioning and refrigeration. “Adding insulation and scaling back expectations need to be part of the package, but the right combination would be peak shaving. Entering and exiting a harbour at low speed is not good for an engine; it’s better to use electric motors when you only need six knots.” He has a 25-metre high-latitudes yacht in construction that will enjoy hybrid propulsion.

Credit: Royal Huisman

“We find peak shaving very effective in that crew don’t need to start up another generator for a short period of extra load that can be handled by the batteries,” says Royal Huisman project manager Henriko Kalter. “Project 404, a 59.7-metre sloop, will be fully diesel-electric, meaning [there will be] no main engines but a system that pulls power for all uses off a grid fed by several smaller generators. These are just for recharging and can be smaller than mains.

“Let’s say your peak load when everything is on is 100kW, but the rest of the day it drops to around 25kW. It’s not good for a 100kW generator to be running at 25 per cent load – the maintenance is awful. So if we put in a 50kW generator, we charge the batteries when power consumption drops below 50 kW and draw from the batteries when it goes above. It also allows us to use a more basic DC system for everything, which gives us more options, such as two retractable electric drive legs.

“Our ‘smart energy’ approach has two pillars – one to reduce power consumption and one to generate electrical power,” continues Kalter. “We studied where power is consumed on the boats and it’s primarily the galley and air conditioning, which take 50 per cent of the power. Beyond waste heat recovery, we are also recovering cool air. Ventilation systems just dump cooled air over the side but we are using the previously cooled air to pre-cool the fresh air coming in so the ambient temperature is being reduced in two steps.

“We are also looking at hydrogen and we have been talking to Lloyd’s about storage safety,” says Kalter. “The problem is availability. Can you go from Antigua to the Med on hydrogen? Probably not. We look to solar and hydro-generators when the boat is under way, [so] it’s not one solution but many contributors to becoming autonomous. We think a totally fossil-free boat is possible.”

Sunreef Yachts’ Eco 80 is covered in solar cells powering enough battery capacity to allow silent mode all night long
Credit: Sunreef

Catamaran builder Sunreef Yachts introduced its Eco line with an 18-metre at Cannes 2019. Now it has scaled up to a 24-metre that will be available in both power and sailing versions. “Electric power is the basis but we take it further,” says Sunreef Yachts’ Artur Poloczanski. “The boats are designed with enough battery capacity to allow silent mode at night, and we use a non-toxic silicon bottom paint that is slicker than most paint, so there is less resistance. We have also used reclaimed teak for the soles inside the boats, and having water makers with purification means you don’t need to lug around plastic bottles.”

A recent source of pride is the yard’s design of integrated carbon-fibre bimini tops that take advantage of new high-output solar cells that can be curved – both saving weight and improving aesthetics. The E series boats use these same solar cells in curved sections of hulls and decks. “We believe that 32kW peak generation from solar is achievable. Wind and hydrogeneration add more self-sufficiency,” says Poloczanski. “Eco design and construction is a main focus for Sunreef now.” Sunreef’s own R&D has led to counter surfaces being made of compressed paper and resin, and components made of flax and basalt fibre, rather than fibreglass.

Tripp has several parallel hybrid projects under construction of sizes varying from 13 to 27 metres. “It’s the Prius model of batteries and an engine. Even if you had the 80kW of a Tesla battery pack you could only power your boat for about two and a half hours at full power – there’s not much excitement to that. You need a source to power the batteries.

Credit: Tom van Oossanen

“Hybrid systems are trickling up from simple systems on small boats and trickling down from huge ships,” says Tripp. “We found a flywheel alternator that looks like a six-inch pancake that fits between the gearbox and the engine. Under sail [with the propeller set in reverse] you lose maybe half a knot. When more systems are available, there will be more acceptance.

“Hydrogenerators with even a small propeller on a standard shaft can generate about 10kW, which makes them quite practical for small boats,” continues Tripp. “But superyachts have a different problem because of their greater loads and the number of people aboard. I’m always running into captains who says they have to keep the boat closed down to preserve the fabrics and woods inside. That’s a choice. I think we need to be less precious and design boats to be able to open hatches.”

“You absolutely can regenerate enough energy to cover the hotel loads on a sailing superyacht,” says naval architect Bill Dixon. “Black Pearl has proven that it’s possible under way with hydrogeneration and solar cells charging battery banks.”

Dixon, a proponent of the Dynarig, is developing concepts that marry the spaces associated with a motor-yacht lifestyle with the green credentials of a sailing yacht. We have enquiries from people now, mostly younger owners, who are putting their companies through sustainability analysis and realise their yacht should meet the same standards.”

Reduce, reuse, recycle

Naval architect Rob Doyle says he’s been “stripping away stuff” from his designs. “I’m always asking, ‘Do you really need that?’ It turns out owners like natural ventilation and a boat that can be silent for 15 hours.

“Boats got heavier because yards got worried about warranty issues and redundancy [so they] upsized and duplicated gear, adding cost. The lighter we make them, the cheaper it gets. Carbon fibre costs nearly twice the price of aluminium, which is totally recyclable and the hull will be close on weight. It’s often the stuff inside that’s heavy.”

Take the new ClubSwan 80 for example. Currently under construction at Persico Marine, Nautor's Swan's latest addition to its series of performance sailing yachts recycles carbon-fibre from previous moulds by separating the carbon from the resin to create new moulds. Persico also collects prepreg scraps and ship to a company specialising in medical prostheses.

YYachts, a company based on the concept of light, efficient, uncomplicated boats, plans to show its new 21-metre Y7 Cin Cin at the Cannes show. Its deck is laid with sustainable engineered wood from Lignia that looks like teak, weighs the same and mellows to the same silver grey.

YYachts also internalises environmental protection. Founder Michael Schmidt insists that subcontractors come from within a 100-kilometre radius to lower transportation costs and reduce the carbon footprint. “We digitalised the shipyard as much as possible to reduce travelling and installed LED lighting everywhere. In addition, we use second-hand shipping containers as office space and let a couple of sheep take care of the grass in front of the yard,” he says. “We are also focusing on new materials we can use on our projects, such as green resin foam generated from recycled PET bottles.”

“If a customer’s company has to meet zero-carbon status by 2030, then their personal possessions probably also should,” says Kalter. “We are seeing more owners moving in this direction in tender packages we receive, some even coming from motor-yacht owners. It’s not that they want to do regattas, but they don’t want to give up the yachting lifestyle.”

Voicing cautious optimism, Tripp adds, “We’ll see all these things come to the fore, hopefully driven by clients demanding it rather than by naval architects saying you could have it.”