Partner and manager of two marinas in Mallorca for 15 years Oscar has been designer and consultant for marina projects in various countries, and designer of customized marina elements. He has shared his experience through more than 30 conferences in 12 countries and has written numerous articles for Marina World and other international nautical magazines. Oscar is a Certified Marina Professional, was founder director of the Global Marina Institute, member of ICOMIA’s Marinas Committee, member of PIANC Recreational Marine Committee, Convenor of ISO TC228 WG8 “Yacht Harbours”, member of the Global Marine Business Advisers (GMBA) group and founding member of the Asia Pacific Superyacht Association
Electric propulsion is actually a very old technology. Moritz van Jacobi built the first electric boat in 1839 and the popularity of this propulsion type grew until about 1920, when it was decided fossil fuels were more practical, due to the weight of the engine, transport, and storage.
At least that was the case, until we realised that we had neglected the environment: Welcome back electrics.
Virgil, in The Aeneid (Virgil, Aeneid, II, 49), proclaims “Quidquid id est, timeo Danaos et dona ferentis”, meaning “Whatever it is, I fear the Greeks bearing gifts” when he tells how, in the Trojan War, The Greeks built their famous wooden horse, holding soldiers hidden within. Once the Trojans brought the gift through the gates, the Greeks got out of the horse and looted the defeated city. The term ‘Trojan’ is used today to warn of things or actions that look like, and could be, something else, potentially much more harmful.
Today I am going to remember Virgil, 2000 years later, and I say: beware of electric propulsion and the promises of a universal solution to pollution.
Electric propulsion is a solution to pollution by emissions, there is no doubt about that, however, the marketing of this apparent miracle-solution fails to mention situations that, if they are not solved at the same time as the appearance of electric boats, will mean that the practical use of these is much less rewarding than promised.
The most developed types of electric recreational boats so far rely on two sources of power: the fuel cell and batteries. The fuel cell is associated with hydrogen, but in reality, it can work with ethanol, diesel oil, gasoline or gas, varying the emission levels released into the atmosphere and the fuel efficiency/power supplied.
When it works with hydrogen, it does not generate emissions. Hydrogen is not easy to transport because it must either be pressurized and cooled to 253 degrees below zero, or pressurized at room temperature at 350bar or 700bar, so that the volumes are manageable. To make a simple comparison, the air in a diving cylinder is compressed to between 220 and 300bar. The fuel cell is stackable and power can be added to an installation by increasing the number of cells. The cells are relatively small – a 30kW (40HP) cell is the size of a standard laser printer. In June 2022 I was, in Sneek, in the Netherlands, aboard a 20m sailboat with two 30kW cells and two 20-litre hydrogen tanks each at 350bar. With those 40 litres of hydrogen, it could do 100 miles at 8 knots, which beat a conventional engine four to one in terms of performance. But with a lack of places to refuel hydrogen, that 100 miles is the end of the journey. And it’s expensive when you find it – today, hydrogen propulsion costs three times than diesel.
The most common batteries are lead-acid (PA) or lithium-ion (IL). They are both heavy, but the lead-acid ones more so than the lithium ones. The PA are more voluminous (two to three times) and must be installed in a vertical position for their vents or plugs, while the IL, sealed, can be installed in any position, although being sealed makes it possible for them to explode, as we have sadly seen.
With the use of batteries, what the user will first notice is that the real autonomy is less than what is advertised. As in cars, these calculations are made considering ideal weather conditions and ideal battery temperature – when batteries get hot, their ability to deliver energy is reduced. If the boat is heavily or unsymmetrically loaded, it will demand more power from the engine, and the engine in turn will demand this from the batteries. Each sailor must, with reasonable caution, engage in a period of knowledge building, accustoming oneself to the new propulsion.
Just as airplanes measure their age by take-offs and landings, batteries do so by charge cycles. A battery is never eternal, current batteries have a life between 3,500 and 5,000 charging cycles, which if we translate it to weekend and vacation use, is about 170 cycles per year, which would give us a theoretical life of between 20 and 35 years (these are approximate calculations, we will only know when the first batteries start to stop working!) Batteries deteriorate throughout their life, and an average life of a boat battery is five years. No one has yet created a regulation (although there are similar ones, for batteries from solar installations) to recycle the enormous number of batteries that we will have from approximately 2040 onwards…
Batteries are and will remain very expensive. Marinas must adopt the necessary standards as it will be their responsibility to dispose of the old batteries legally. Ports will also have to decide what type and how many pedestals to install. Batteries can be charged in three ways: with the common pedestal (charger on the boat, slow charging), slow charging (the charger is in the pedestal, it sends direct current directly to the batteries, like in cars) and fast charging, which is the same method but with high amperage, and this requires a medium to high power electrical installation at very high cost.
When electric propulsion vessels begin to proliferate our ports, battery charging pedestals suitable for the vessels that require them, and the density of use, must be installed. Base vessels will merit the installation of their own pedestal, and transients will need to be assigned to berths that have charging pedestals. Why? Because there are few ports that can afford a complete electrical installation and maintain the traditional pedestals for those that continue with thermal engines.
The learning and accustoming period should be spent with a hybrid system: in addition to batteries and charging system, a generator that allows for return to port at a reduced speed. This system could be bought or rented by the same builder of the boat, by the marina or by the club. In addition to this, ports should really be increasing the number of support boats and towing boats, because the number of electric propulsion boats that run out of battery before returning to port will be high! It cannot be expected that Maritime Rescue will always be on hand to help these apprentices of electric propulsion.
Having listed some of the situations that we will encounter when adopting this technology, we must not overlook the training of port personnel. Training must be given in the control and combat of lithium battery fires, which require special elements and protocols. Grouping electric boats in a specific area where there are more specific fire-fighting aids for lithium batteries is still a possible increase in security, as is ensuring the free passage of fire trucks to that same area.
Electric propulsion is efficient, safe and in most cases cheaper than hydrocarbons. It is here to stay, it will be part of the regulations, and it will evolve rapidly in the coming years. But we still have a long way to go before we are capable of adequately receiving these vessels of the future in the ports.
