Among sailors, diesel engines have become so ubiquitous that few seem to be able to imagine any alternative. Yet, of course, that hasn’t always been the case. However, during my lifetime we have seen them steadily increasing in power and boats becoming more dependent on them, not just for moving but also for charging batteries.
In part that is with busier, more complicated lives, diesel engines have become a way of feeling more in control and able to keep to a fixed timetable.
However, a key thing we love about sailing is the process of sailing. We love making even the slowest progress in light winds. Even in the worst weather we are going to be drier on Vida than we have been on our Sprint 15 and Rivals have an outstanding reputation for going to windward in heavy weather, so we are not looking to motor to avoid sailing to windward or reduce the time spent doing the very thing we want a sailing boat for – sailing.
But not everyone is like us – phew, I hear you say 😂
So why would anyone choose an electric motor instead of a diesel motor? Are there really any advantages? Well we think so, this isn’t a punishment for us but a really positive life enhancing choice.
The advantages of electric power:
Fossil Fuel Free
An obvious point. The climate emergency absolutely requires us to stop burning fossil fuels. If politicians acted in our bests interests then we would already see diesel being phased out rapidly for new boats and a not too distant deadline for replacing all fossil fuel engines in boats. It is going to be essential and given our agenda of Sustainable Sailing it is hard to justify not making this change now.
But hopefully we can demonstrate here that stopping fossil fuel use (at the least direct fossil fuel burning) doesn’t mean taking away life, freedom and joy. In fact quite the opposite.
Trading initial expense for reduced running costs
Because this change means taking out something that works (probably, we haven’t been able to fully test it yet) and replacing it, there is considerable initial expense. The electric motor and controller is cheaper than a new diesel engine but the batteries alone are probably a lot more than upgrading fuel tanks (so they can be inspected and cleaned) and fuel system (so that it can be accessed and cleaned if it gets blocked by sludge). That is a bit of a guess as we haven’t priced doing that work to the current system (because we are just not interested in spending that much time and effort on it).
The electric motor also needs various the connecting bits (solar panels, mountings, chargers, etc etc), but almost all these benefit other systems too such as power for electric cooking, so hard to treat completely separately.
However, once installed we will have essentially free fuel (we might need to pay for an electric shore power connection occasionally, and we might carry a small portable petrol generator for power shortages if we decide to go to Northern latitudes in winter). Given that we have seen YouTube liveaboard cruisers who are spending $500 a month on Diesel when cruising in countries like Norway the free fuel savings add up quickly.
The diesel is not the only cost saving, there are other consumables as well (fuel filters and oil for example). Electric motors don’t need any of these.
So we would expect to recoup the purchase cost within the first 4 years – and that is just going to be holidays and a sabbatical. Sooner if we cross France via the canals which would require maybe a month of motoring nearly all day everyday.
However, the initial cost of an electric system also needs to be compared to what we would have to pay if we kept the diesel engine. That needs quite a bit of work: a full service, new filters, tanks to have inspection hatches fitted, fuel lines to be replaced (because there is no access to unblock the current ones if sludge gets in them, some of the valves are broken and some of the copper pipe is pretty corroded), water cooling inlet seacock to be replaced and a new starter battery. By changing now, without doing any of this work we are already significantly cutting into that extra initial cost.
Much less maintenance
We have chosen a brushless electric motor. There are no parts to wear out in daily use. It is air cooled so there is no water cooling system to maintain (no seacock, no salt water to corrode anything or leak). There is no gearbox, just a long lasting toothed belt with pulleys to act as a reduction gear. No oil to change, no fuel system to ensure is clean and free of water or other contaminants.
When you watch the YouTube channels of people with electric motors (eg Sailing Uma, Beau and Brandy, Rigging Doctor) and compare then to those with Diesel engines (eg Sailing La Vagabonde, Saling Yacht Salty Lass, Tula’s Endless Summer) you will see orders of magnitude differences in the amount of time spent working on diesel engines compared to electric motors.
This drawing shows just how much space we are going to gain in our cockpit locker and corridor to the aft cabin. All our batteries will fit (along with the electric motor and both inverters and our solar controllers) in the existing engine compartment. In fact it seems to me that the fuel tanks are higher than shown in the drawing, taking even more space.
We are not yet sure what we are going to use the corridor space for (maybe bike storage) but the cockpit locker is going to be massively bigger and should take most of our sails, fenders and ropes. That is a huge gain for us as this boat design doesn’t have a huge amount of storage space. The only other storage on deck is a lazarette (locker at the back of the deck) that used to be used for the gas bottles. We will probably use that for the electric outboard engine and other bits we don’t need when on passages.
As we know from electric bikes and cars, these motors are almost silent. Life inside a boat cabin is pretty unpleasant when a diesel engine is running, far louder than a car. So we expect to really enjoy this benefit. We might even end up motoring more as it will be free and silent. Slipping gently and silently up a still river while not disturbing the wildlife sounds beautiful.
As we have been removing the old headlining it has been startling to realise just how much dirty air was escaping the engine compartment into the cabins. All around it, behind the headlining is a black sticky residue. Yuck! No wonder so many people feel seasick if they go below when motoring.
This one is going to be contentious 😁
We believe that becoming dependent on a powerful engine being available all the time and expected to be able to drive you at hull speed for hours at a time whatever the conditions is dangerous. It leads to taking risks and being unprepared if the engine fails. For example it could be a skill shortage or just not having been bothered to get the sails (and anchor) ready for immediate use or to be somewhere where you couldn’t sail out of danger. The RNLI stats I shared in an earlier post support this.
While we will have more limited range and not be able to run at full speed for hours at a time electric motors have other safety advantages. No fuel to get contaminated or blocked (and remember if your electrics fail you won’t be able to start your diesel engine either). Full torque at all revs so doesn’t stall and has more usable power at low speed. Also unaffected by being tossed about by the waves.
Diesel is nasty stuff, it gets everywhere, it is hard to clean and it smells. But a diesel engine also requires you to store smelly oil and change dirty parts. It puts out smoke and pollutes the water you will want to swim in.
Freedom from supply
This is a big one. No need to go anywhere to refuel (and there are no fuel docks at Beaumaris, or at lots of remote places). No need to go ashore with the dinghy to hunt for fuel and carry it out to the boat. No worrying about the quality of fuel that you are able to get in remote places. No need to carry extra fuel in Jerry cans on your side decks.
Far fewer spares to carry or have to find a supplier for. In fact if you are paranoid you could take a whole spare motor in a smaller space than the spares and engine tools that lots of people carry (even wrap the spare in layers of tin foil and it will probably survive a lightning strike – try that for a diesel engine). No waiting to ship parts specific to your engine to remote places.
Electric motors, especially when powered from renewable energy generation, are incredibly more efficient than a diesel. Even an electric motor powered by a diesel generator is now more efficient than a diesel engine itself (because you can always run the generator at its peak efficiency rather than than it be set by the speed you go at).
The efficiency difference is made even greater by using the electric motor to generate electricity when you are sailing rather than just sitting there as a dead weight just slowing you down.
Enough for now
I’ll write a separate post about the disadvantages which won’t be as long 🤣
We expect to see huge growth in the number of electric boats over the next few years because these advantages are so huge.