Green tech solutions for yachts

More than any other sportsmen and women, sailors see the havoc that mankind has done to the world’s environment. Off the UK, warm water fish are heading further north up the coast, while colder water fish are retreating.

Plastic is everywhere, while sailing at dusk a few miles offshore you can see the filthy air of cities just over the horizon.

Living with the environment, it is only sensible to protect it, right?

Green technology

Over this blog we will explore how to make your yacht passages carbon neutral from using electric motors to drive the boat, to generating your own electricity, and finally the lazy person’s way of paying someone to offset your carbon emissions for you.

Green technology is really advancing these days, to the point that many multinational companies are bringing in renewables to their energy use for a guaranteed power supply where once they would have chosen fossil fuels.

If the big guys can do it, why not you on your cruising yacht?

Electric motors

Electric motors are coming of age now. They are efficient and weigh the same overall as a diesel system.

A 2015 article in Blue Water Sailing summed up the advantages:

“A complete system weighs about the same as a comparable diesel with full tanks, but the batteries can be located nearly anywhere that the weight serves the boat. And unlike diesel, which is consumed, the batteries can be used in place of ballast, thus making the entire boat lighter and more nimble while freeing up internal storage space.”

Another thing is the silence - you won’t have to shout over the noise when you are running under propeller power even when going flat out. Don’t we all enjoy the silence at sea?

You do need to think about the rest of the electrical system though. We will go through these issues in the sections following - batteries and energy generation.

Lithium batteries?

The next thing you should consider for your yacht is a good set of lithium batteries. They are lighter than lead acid. One expert explained it it this way:

“100 to 250 watt-hours per kilogram for lithium-ion cells, compared to about 45 Wh/kg for the most energy-dense lead-acid cells available and about 18 Wh/kg of usable capacity in a typical deep-cycle marine battery.”

Lithium batteries also take a far quicker charge. While lead acid batteries can take around 0.25 amps per amp hour, lithium batteries can be charged at around 100 times faster.

There are two drawbacks - lithium batteries are less safe than lead acid and they cost a lot more. You just need to look at how the Samsung phones took to exploding to get an idea of what can happen if mishandled! This can be offset by taking proper precautions in the area of the boat they are kept

As to their cost? This is plummeting every year.


A new technology is coming to maturity in sailing yachts, where you have a special propeller dragging in the water.

Instead of driving the boat, it spins as you travel and the spinning generates electricity that is put into the battery bank. Yacht racers have been using these for years but the technology is starting to reach the cruising yacht market.

For around 3800 euro you can install a Watt and Sea cruising hydrogenerator on your boat.

This will start putting charge into your battery at about 2 knots and works well at around 5 knots. Let’s face it, 7 knots is a good clip on most cruising yachts!

Solar sails

Why not turn your yacht’s mainsail into a solar cell?

Tested on racing yachts, solar cells are laminated to the sailcloth. A solar energy supply blog described the system:

These cutting-edge, light-weight films can generate electricity in low light and indirect sunlight.
Solar sails
They are supple enough to handle the sail being luffed as well as folded.
The panels will be put in the upper part of the main, above the third reef.

Unless you’ve furled your sail you will have energy supply. Not a bad gig that is it?!

Solar cells have been around for decades, but the technology is just about reaching maturity. The whole of the cloudy and stormy UK could cut around 50% of its fossil fuel emissions if it took solar seriously using available technology.

Wind generation

Yachts have had wind generators for years. Now the technology is what it is, for around 1200 euro you can buy a piece of kit that should keep your battery refreshed in most conditions.

In a recent product review, Sailing Today recommended the AirBreeze range of wind generators in terms of quality and the most reliable energy output.

Carbon offset for the lazy

Did you know you could tap into the commercial carbon trading system when you go sailing? This is by far the cheapest approach to tackle your carbon emissions in this blog. For every 400 litres of fuel your yachts uses, you will pay less than US$1 to offset your carbon emissions used while afloat!

While focused primarily on the superyacht end of the market, the company Yacht Carbon Offset will happily deal with smaller cruising yacht sailors as well.

Under the international carbon trading system, ‘carbon credits’ are generated by emission reduction projects such as renewable power stations that need supplementary funding to get off the ground. The quantity of emissions saved as the result of each project is calculated by an auditor and this drives the number of credits issued.

There is now a well-developed set of international standards governing this. Carbon traders buy these credits and sell them to businesses and people who wish to neutralise their fossil fuel environmental impact.

There are other projects around the world too. You can support the regeneration of wetlands and sea grass habitats through a charity in the US. The 2015 Volvo Ocean Race stopover in Newport, Rhode Island offset their carbon emissions by paying for around an acre of wetlands to be regenerated.

The chief criticism of these schemes is that you are emitting carbon in the first place. Not all carbon offsetting schemes are very good either.

For example, if your carbon credits come from a hydroelectric plant in Brazil, thousands of indigenous people may have been thrown off their ancestral lands and millions of trees may have been cut down to prepare the project.

Not so environmentally friendly after all…


A new environmentally friendly antifouling system for the bottom of your yacht could also used on many of the above water surfaces of the vessels too.

Looking at a pier or dock you will find a whole ecosystem of shellfish and plants attached to it just below the surface of the water. This happens to boats of all types if not tackled, and this can cause huge amounts of drag, slowing the vessel down and making powered travel a lot less efficient. It is estimated that a vessel with weeds and barnacles on the hull can be slowed down by as much as 28%.

The answer has been therefore to use an antifouling paint on the hull. For many years a coating of tributyl tin paint has been used on most craft to kill off organisms as soon as they attach to the hull. The main issue with this is that concentrations of this substance can really poison the water. Harbours are one example where the water can be very toxic to wildlife due to concentrations of tributyl tin. The upshot is that the European Union has banned it.

Since the ban, companies have cast around widely to find a durable alternative. It has been a very hard thing to do, but recently a new ceramic coating has been discovered that is very hard for any creatures or plants to stick to. When applied it creates a perfectly smooth surface that is incredibly difficult to bond to as even at a microscopic level it appears to be very smooth (as against paints and gelcoats that are cratered and pockmarked, even while appearing smooth to the human eye). It is also hydrophobic, meaning that water just beads off the surface, carrying the dirt away.

In addition, the antifouling releases low levels of copper oxide ions that are very unpalatable for shellfish and seaweeds to bond to. Being hydrophobic it has been shown to improve the speed of the craft through the water too – of two identical vessels, one with the nanotechnology antifouling coating and the other without, the vessel with the antifouling we use will soon pull away from the other boat too.

Every chemical ever used by mankind has some form of toxicity to the environment. This is why durability is important. The antifouling coatings only need re-application once every five years or so, meaning your boat will have more service time afloat and also meaning that they are kinder to the environment than most other boats afloat today.


It is possible to go carbon neutral or even carbon negative by spending a little money. While the cheapest way is to go through high finance, the best way may be to spend a few Euros on making your boat generate no emissions at all. Ultimately it is down to your conscience and the world you want your children to inherit from you. Do you want climate change calamity for your kids to mop up or do you want to minimise your impact from your hobby in the first place?

See Also: Environment (Sailor's Guide)

Richard Shrubb