Electric Propulsion

Over the last few years a lot has happened in electric propulsion – major breakthroughs and innovations. From being a weird ‘nerd’ or ‘hippie’ who drives or is trying to drive an electric bike/car/scooter, we’re now consider driving an EV pretty cool and awesome, with Elon (the Tesla guy) becoming some new kind of Rockstar. Mostly, it has been accepted as the new reliable normal. Nowadays and especially in richer countries fancy EV’s are so common that you are no longer surprised by their quiet presence. Charging stations emerge like mushrooms in the fall. E-bikes, scooters, skates, drones are like the plague. All relying mostly on some sort of lithium batteries, like our phones and computers, who after years of misuse still provide some remarkable capabilities. Some will probably argue that their battery sucks etc. But deep down inside, you must be impressed by your phone or electric drill or fancy battery driven tools, which now allow you to even work on a remote anchorage for hours. You also have to be impressed about the drop in cost in all battery driven appliances.

With EV’s and batteries expected to become even more price and range competitive, the options/solutions emerging are numerous. As green premiums are shrinking to zero or even becoming negative, nothing can stop the trend.

But you know all this, so what about electric propulsion for boats? Well there are several emerging or established companies that offer exactly that, a replacement for your dirty lady. Unfortunately the green premium is still high and, as always, marine products are by default extremely expensive. But hopefully demand will change that. Via a little research we’ve found that the cost of an electric boat engine is probably comparable to or maybe even cheaper than a new diesel alternative. This however does not include the batteries (your fuel), which is causing another financial burden/investment, although definitely expected to further drop in price we are still talking about a huge amount. 

But before you say “leave me alone with this fancy shit!” let me share our little dream or vision for Dory Man and yachting in general. Once our engine gives up – we will hopefully win the lottery (because otherwise our sailing dreams are fucked). We then salute our lady (engine) for the last time and get rid of all the oily remainders and the engine associated. Then we use parts of the engine and fuel tank space to build a large lithium battery bank and get rid of our other batteries – one central powerful bank (simplicity should be the target) connected to a large solar array (400-600 watts, maybe more). Then we install an E- engine (they are tiny, so more space for batteries or perhaps a wine cellar? ). Even with a huge bank we would still probably have only a limited range of 20-30nm on slow speed, but we believe that we could live with that. All of the above would be powered by the sun, wind or by the hydrogenerator (included on most E drive propulsion systems – your actual propeller is driving it). So while sailing we could sacrifice 0.5kts to charge up for the upcoming use. The sun and/or wind charges by default and if we are stuck in a cloudy windless place (well we have failed and might stay there forever). Ok maybe we could get a small dirty generator, which would also increase the range (if charging at the same rate as discharging we’ve build yourself a hybrid), killing the green however. 

So if you can live with a small range, you might actually have a pretty sleek autonomous system. No more diesel, high amounts of electricity for any use, fast charging* and if used well, a long service free life. To me this sounds pretty cool. But we don’t even play, so how do we win the lottery? How to afford such an investment? Well we are trying to figure it out (hopefully our lady/engine gives us some time), but it will definitely be worth it.

*Charging, if you are nerdy enough you might actually do some maths and come up with the many hours of sun required to charge such a large battery bank (21 +hrs or so with 600watts of solar for a 13kW battery bank if I am not wrong), but anyway if able you can charge lithium pretty fast, while you have a reason to stay at this sunny anchorage a day or two longer. Also most of the time you really just use your engine just to get in and out of an anchorage/harbour.

Pros: 

• Reduced maintenance – no oil/fuel filters, impellers etc.
• Less through-holes (for the anxiety- driven sailor or ones suffering under try-phobia).
• Lower complexity, the battery bank may be a but complex, but you have that anyway.
• Reduced noise -hardly any.
• Large amounts of electricity available from the battery bank.
• Apart from the impact the production (arguably lithium etc. is often not mined in the most ethical way & recycling of batteries etc. is often problematic), operating impact will be low or near zero if you manage to charge by sun/wind/current.
• You can use it to increase your speed on low wind – sunny days without feeling guilt, or simply to win an imaginary race with some other faster bigger boat – no smoke, no noise, no suspicion.
• You will actually sail more.

Cons:

• High initial costs – but increase in demand will hopefully lower costs.
• Limited range, small energy density in today’s batteries will be a non-solvable issue (could be extended by a generator – killing the Green purpose).
• Limited proven reliability and available knowledge (service points & spares might be limited)
• Charging speed and options (not every climate or boat has the ability to provide sufficient power to charge such large batteries).
• Some complexity, in the form of highly advanced battery systems that need some sort of good knowledge and faith.

If you can afford it and you can work around the range issue it’s definitely worth it, but that’s too simple isn’t it? In our opinion, it’s really only about the range. But you could as mentioned work around that with a generator just in case.

The price shouldn’t be the deciding factor, especially when the difference might actually play out to be rather small. Of course that’s only the case if you need to upgrade the engine anyway. You will still need a good battery bank and solar array,  so you might play with the idea of going big and dropping some more cash for an E-drive, and then you only need to add the electric motor, having actually spent less – especially considering all the pipes and parts, soundproofing, services etc. a regular diesel requires. Another option is some sort of hybrid, in case you happen to have a larger battery bank sitting around, you could look into some options or engineering a hybrid (great for harbour entry/exits etc.) Finally you might be a E-geek with some money, then apparently you can use a recycled lithium battery bank and a recycled industrial electric engine and make it yourself- especially interesting for small coastal cruisers or day sailors.

Overall the idea of having a self-sufficient/autonomous propulsion system, while being green is an idea definitely worth considering and investing in.

A little rough price comparison for the end:

	Diesel	Electric
Initial investment	~12k € with installation etc.	7-8k € for motor + 8-9k € for batteries + 1-2k € for solar panels = ca. 20k €
Annual costs	Estimated average: 100-200 € for service spares + 300 L of fuel ~ 500 € = 700 € in total costs.	probably negligible

So after 8-9 years (assuming no major damages) you have paid of the investment. Furthermore, you have batteries and solar included. So it is really not about the price.

Please share your thoughts and knowledge, maybe we are just too naïve.