The question of how to adjust our daily lifestyles to be as sustainable as possible is now a major concern for those of us who live on land, but also at sea. We are becoming increasingly aware of the relationship between our energy consumption and environmental problems. Air pollution, climate change, water pollution, thermal pollution, and solid waste disposal are all directly related to the production and consumption of fossil fuels.


It is no surprise therefore, that yacht owners too are questioning their impact on the environment, and raising the very pragmatic question: to go electric, or not?


Electric engines vs. combustion engines can be a hard topic to navigate in the context of hybrid catamarans. Electric engines are being heralded as THE solution for reducing our CO2 emissions. But there are a lot of questions: Is the technology advanced enough to be a reliable option for blue water sailing boats? Is this the most sustainable solution? Or is there an element of greenwashing going on by boat manufacturers who are trying to appear ‘climate-friendly’?


At Outremer, we understand the need for an objective perspective in this debate on sustainable yachting. Our expertise in marine engineering, our close relationship with our customers and their feedback, and three years piloting the zero-emission model ‘4-zero’, enables us to offer you this balanced perspective on hybrid catamaran solutions.

Enjoying the Dream of a Fully Electric Boat


The Idyllic Vision


Picture yourself living your dream. You are on your green fully electric, emission-free sailing boat basking in paradise. The sun is just dropping below the horizon. You are gently swinging on anchor, dinner is cooking, and you are enjoying a cold drink after a refreshing swim and a warm shower. The spot you chose was perfect – idyllic, sheltered, and not another boat in sight. Yesterday, you set sail for a 200-mile passage – fridge stocked and water tanks full. After slipping the lines and hoisting the sails – thank goodness for the electric winches – you turned the engine off and breathed a sigh of relief; that moment is the best when it’s just you, the waves, and the wind. For the rest of the day and night, the autopilot did the rest of the work, obediently following the route you set in the chart plotter. Apart from some fine-tuning, all that was left to do was relax and enjoy that wondrous feeling of traveling entirely with nature. 24 hours later, under the warm fiery glow of the setting sun – truly – you feel recharged. The boat’s batteries, on the other hand…


Energy Consumption Breakdown


In 24 hours, typically a 45-foot Outremer will need about 10kWh of electricity. That breaks down to:

3.5 kWh for the critical sailing electronics

4 kWh for other domestic appliances like a fridge, freezer, electric winches, and interior lighting

1 kWh for heating 40 liters of hot water, enough for four people to shower and wash up frugally

2 kWh for cooking two meals with an induction hob, boiling a kettle via an inverter, or making 150 liters of water with the watermaker; possibly running the dishwasher or washing machine.


Practical Considerations


NB: While this data comes from real-life experience, everyone’s power requirements, generation, and storage are unique. These figures may not directly relate to you, but we encourage you to take a pragmatic view of the power you will use and the power you can produce and compare them as we have here.


The Possibility of Renewable Energy


The good news is that if you have a fully electric boat, it is theoretically possible to generate enough renewable energy to cover your daily needs. On a sunny day, solar panels on your davits and the coach roof will just about generate the 10kWh needed. If it is cloudy, your average speed of 8 knots might produce 4 or 5 kWh – which wouldn’t be enough for all the comforts, but you could still run your electronic systems and the fridge.


The Challenges of Light Winds and Cloudy Days


The bad news is that if you have an electric boat and find yourself in light winds on a cloudy day, power generation gets tricky. For coastal cruisers, this can be overcome by planning trips around marinas and shore power plug-ins to top up. But for blue-water sailors, this is too much of a risk. Power on board a yacht is needed for critical life support systems at sea such as creating water, propulsion in an emergency, or running electronic equipment like GPS and a VHF radio. As blue-water sailors know all too well, nature and the weather are notoriously unpredictable. To rely on any type of consistency with wind or sun would be foolish.


Safety Concerns


So, for now, a fully electric boat is impractical and unsafe unless you are prepared to simplify your systems onboard down to the bare minimum: no fridge, no water maker, and very basic electronics. And even then … is it feasible?

Hybrid Catamarans: Benefits and Challenges


The Hybrid Alternative


The now frequently used ‘safer option’ for alternative to a fully electric boat is a hybrid. On first look, this appears to solve the risk of running out of power onboard a boat with electric propulsion. However, this is not a sensical option. Adding a diesel operated generator to a boat with electric propulsion leaves you with the worst of both worlds.


The Clean Energy Dilemma


One benefit of an electrically powered boat is that it uses clean, renewable energy. Put on a diesel-powered generator and you might as well just put the diesel engines back on because you are still reliant on fossil fuels. Another benefit of an electric propulsion system is that it is quiet and clean. But once you run the generator you negate that benefit: the generator is noisy and needs a smelly exhaust just as an engine does.


Weight Considerations


A much-celebrated advantage of electric propulsion is that it is much lighter weight than a diesel engine, especially when you bear in mind the weight of the fuel itself. However, once you combine the weight of the two electric engines, sail drives, extra batteries required, and then also the generator and the fuel that needs to be stored, the resultant weight is within 100kg of the weight of the two diesel engines and their fuel. That’s barely the weight of an average crew member and their luggage.


Real-World Testing: The 4-Zero Model


That’s the theory – but what about the reality? The Outremer shipyard has been offering the ‘4-zero’ – a ‘zero-emission’ fully electric boat – for the past three years. It’s first prototype was created for Jimmy Cornell’s ‘Elcano Challenge’ which aimed to follow the footsteps of Magellan on a 33,000 mile journey around the globe in total carbon neutrality. The first part of Jimmy’s expedition took him 1000 NM or so from La Grande Motte to the Canary Islands and allowed him to better understand the constraints that modern day sailors face if they wish to sail fully electric.


Cost and Performance Challenges


That began with the boat’s cost which was 30-50% higher than an equivalent boat equipped with diesel engines. The most significant takeaway from this voyage was the power required for propulsion relative to sea state. Whilst in a flat sea and no wind, 4-5KwH were needed to propel the catamaran. But as soon as the wind picked up, the power needed to propel the yacht increased exponentially. By the time they were motoring into 25 knot headwinds and their associated chop, the power necessary to move the streamlined hulls of the Outremer increased to 25kWH. That’s still more than the solar panels and hydroprop could produce on a day with full sunlight whilst sailing at 10 knots.


The Path to Sustainable Sailing


It is clear now that Outremer, nor anyone in the boating industry, has yet solved the task of providing a truly energy autonomous solution for blue water sailors. What is clear, is that if we are to adopt green energy solutions, we must change our behaviour. We must go back in time: limiting our power consumption to basic equipment, resigning ourself to unpredictable schedules, giving up going upwind in harsh conditions, and adjusting the route plan to optimise power generation.


Balancing Sustainability and Safety


But none of these solutions solve the issue of safety, which is the most important thing of all both for yacht owner and shipyards: in the case of breakdown, medical emergency or unexpected bad weather are we ready to rely solely on an electric or hybrid engine? We’d say not.


The Future of Green Sailing


Each generation of sailor has their own experiences, values, and visionary ideas. We are committed to finding a solution here that does not rely on fossil fuels. So we invite you to discuss this topic further: how to be green AND be blue-water safe.