Old water tank removed

We took a long time to decide that we would take out the original stainless steel water tank. As with lots of jobs it was daunting. However, in fact it was relatively straightforward. Using the man overboard block and tackle I was able to get it out whole.

Very glad we have done this. It was sitting in a bit of a puddle (looks like it blocked the last bits of water running into the deep section of the bilge).

We already knew the inspection hatches were grungy. We had seen some rust on internal welds. Now we can see that the welds for the baffles are rusting on the inside and outside.

So very happy we have done this.

We can see that we will be able to fit all our batteries in the aft part of this space, that keeps them together and the weight very low). Very happy with that.

We can then have a smaller water tank in the forward end (we will have other water tanks elsewhere). Having multiple water tanks is also a good safety feature. If there is a problem with one you haven’t lost all your fresh water in one go.

So very happy 😁 Jane is going to attack it with bilge cleaner now while I rest my back, that is mostly precautionary but I have had a few more twinges.

Now we are definitely going to 48volt house battery bank

This answers our pondering House Battery Bank: Should we go 48 volt

So we managed to get these two items from the clearance section at Energy Solutions.

The new MultiPlus II (looks like a decent upgrade from the original MultiPlus). Sized with a 48 volt, 5000 Watt inverter and a 70 amp charger. For the price of a much less powerful 48 volt charger on it’s own.

We had planned to have two smaller MultiPlus units to give some redundancy. We don’t really need that before we set off world cruising so we can wait and add a second smaller one in a few years. The feature set is amazing. For example we can have two power circuits on the boat and one of them will only be supplied if we have shorepower or a generator running. Also we can tell it the shorepower capacity and it will make sure it doesn’t overload it. It can do all kinds of clever stuff mixing shorepower, battery and solar in clever ways (that will mean that we can minimise our shorepower usage as the solar is prioritised).

The Isolation Transformer was an even bigger bargain, the case has some damage (looks like it was dropped onto one corner hard enough to bend the side and bottom panels). It can support a 32 amp 7.0kvA mains supply. It handles 230v and 120v, sorts reversed polarity and protects us from electrical currents that can cause metal fittings on the boat to corrode.

We are very much looking forward to getting these installed (might need to do some weight training to get the MultiPlus II up the ladder and it will need a very strong bulkhead to be fastened to).

Our Scandinavian challenges part 2

In Our Scandinavian challenges part 1 I covered the time/permission complications of getting to spend time in the fantastically beautiful (and remote) parts of Scandinavia and the Baltic given the impact of Brexit.

I ended with “In part 2 I’ll look at the other key challenges these cruising grounds have for us (particularly heating and renewable energy).” so here we are.

We are not (definitely not!!!!) planning to spend winters where the sea freezes unlike some of those crazy YouTubers I linked to in the last post 🙂 However, we are going to be spending time where some heating is going to be needed, whether that means wintering in the UK or being further north in the Spring or Autumn (either heading towards to back from a summer in or close to the Arctic). As we are going to be living aboard full-time in or retirement we want to give ourselves as many options as possible.

It should be no surprise that when it gets cold an electric boat that is aiming to have zero fossil fuels gets hit by a double whammy.

If the weather is cold enough to need heating then it is almost certain that you will get very little energy from solar panels (even on those bright sunny winter days the sun isn’t very high in the sky for very long).

If it is cold then you are going to need to heat the boat and all forms of electric heating use a lot of electrical power. Plus of course we tend to prefer hot food and drinks when it is cold and on a n electric boat that too will use lots of power.

So we generate less power but need more power. Ouch.

If we stick with a zero fossil fuels target then there are a number of options to help out but no magic solution:

  • Sail the boat to somewhere warmer 🙂 Given Schengen I suspect Turkey, Croatia, Cyprus and Algeria will be more popular for UK cruisers than they used to be. But the weather in the Mediterranean is no picnic, if anchoring you can end up moving often to find shelter from different wind directions. Winds can be very strong coupled with large waves that might come from a different direction. Another option is to go further south for example to the Cape Verde Islands, but then you could continue across the Atlantic to the best season in the Caribbean 🙂 But we do want the option to be able to winter in the UK so that we can visit family and friends.
  • Insulate the boat better. This is an obvious improvement that miraculously helps in both hot and cold climates 🙂 We have been working on going from zero insulation to a minimum of 10mm closed cell foam. See here for our first attempt to fit the foam – it didn’t stay up. Next plan is here but probably we will put more layers of foam to increase this to at least 20mm and reckon the purchase cost will be worth it in increased comfort and reduced energy use.
  • Heat locally. So rather than heat the whole boat do so in zones (we already have not heated the forecabin at all, in very cold conditions we could close off the aft cabin and stay in the saloon) and also use thicker duvets, heated blankets and hot water bottles (yes we won’t use a hot water bottle with an electric blanket!!) to avoid heating the cabin as much.

However, these are not going to be enough when it gets very cold.

We do have electric heaters (both wall panels and fan heaters). I think we will try some of the low power “greenhouse” style tube heaters under the bunks. That will give us 3 options to compare for warmth, control, comfort and energy use.

Despite all these efforts we are sure that in winter, despite all our solar, we will consume a lot more battery power than we can generate.

That leaves us with two more avenues to pursue. a) what other options are there to recharge the batteries b) what else can we do to make the battery bank capacity last longer.

What other options are there to recharge the batteries

One strategy that solves the problem is to spend time connected to shore-power. We have seen many cruisers on YouTube spend the winter in Marinas (Salty Lasses, Uma, MJ Sailing, Sailing Fair Isle are all examples). This way you get a permanent connection to mains electric. You can keep your batteries charged, have all your electric heaters running and stay warm.

But there are disadvantages. In the UK this quickly becomes costly (a winter marina berth for us will range from maybe about £1,500 for 4 months to £2,500 for up to 6 months that without going to the more expensive parts of the country where £800 a month would be a starting point). More than just the cost is that we want to live aboard our boat so that we can go sailing not sit in a marina for half the year.

So we want to explore options where we extend the time we can manage on batteries and go into marinas/harbours for a night every so often to get the batteries fully charged (and maybe have groceries delivered). It looks like we could expect to pay up to about £40 a night. One option would be to spend a winter along the South coast of Cornwall and Devon. There is beautiful sailing along that coast, lovely harbours, rivers and towns to visit. There are very lots of rivers with good shelter and many where you can anchor (eg Helford, Fal, Percuil, Fowey, Tamar, Yealm, Dart). Then you have a wide choice of marinas and harbours when you need to charge the batteries. If we can keep that under 10 days a month in marinas then not only do we get the sailing and beautiful views we also save money.

One obvious strategy will be to invest in wind generators, given that cold and windy weather often come together. They work out at between £1K and £2.4K per generator (remember we need 48volt ones). Calculating how much difference this can make is difficult, it depends how sheltered a spot you find and the weather conditions. We have a few options for where we might install one or more wind generators. It is important that we don’t end up casting shade onto our solar panels from the wind generators as that would have a dramatic impact on the solar performance. Also, as with the solar panels I would prefer to be able to take them down and inside if we are expecting a storm. If the demountable option works well then potentially we could have a position at the side of the mizzen mast that could be used when sailing. Then we would only put them wind generators up when the gain will be greater than the loss in solar due to shading.

As a starting point I’m thinking one wind generator using a demountable pole fitting towards the bow. With that we would only have the wind generator up while at anchor and it would be as far away from the solar panels and where we sleep as possible so that neither the shade nor the noise will be a problem. That will let us properly evaluate how much difference it makes. If we think it is enough then we could explore other options.

With our ketch rig the only option for that won’t cause shading and can be used both at anchor and when sailing is a permanent mounting on top of the mizzen mast. That doesn’t excite me. The top of a mast is the last place you want to add weight. It will also be moving around a lot in waves which will affect it’s performance. Finally, the foot of the mizzen mast is above the head of our bed. I’m concerned about noise and vibration disturbing our sleep. However, it would be out of the way and (until it breaks) very convenient. If we want that option to be available we need a generator that can be remotely braked (manually or automatically) if the wind strength is too high.

It is very hard to estimate how many nights in a marina having a wind generator would save us. We would have to save about 40 nights to recoup the cost. We could achieve that saving over a couple of winters if we could reduce the need to get shore power to once every 10 days instead of once every 5 days (both are guesses and will be very weather and location dependant). Of course it would also help avid the need for shore power a bit in other seasons, particularly if permanently mounted.

What else can we do to make the battery bank capacity last longer?

The most obvious answer is to install another form of heating that does not use the battery bank. All the YouTubers who have visited the Arctic Circle or Scandinavia in the winter have some form of heating that is not electric. They all say they can’t manage long at anchor otherwise. While our goals are not so extreme (the midnight sun is attractive to us but the sun not rising above the hills at all is not) we would be crazy not to learn from them. So what do they have besides electric heating (that they all only use when connected to shore power). There is a great video from Alluring Arctic on this, our takeaways from what we have seen are:

Wood burning stove

Uma have one of these and we have seen a few others. However, recent reports that we have seen on the high levels of pollution they release into the boat (mainly ash whenever you refuel it) and the air pollution from the chimneys mean we have ruled this out.

Diesel powered hot air

Probably the best known brand is Eberspächer, these install out of sight and burn diesel to heat air. Then then use a fan to blow the heat through the ducts around the boat. They are a more modern replacement for the paraffin heater we removed. The provide lovely warm dry air all around the boat. However, the ducting takes up a lot of space in lockers and they use quite a lot of electricity. Ran Sailing for example can only use it for one night or so before needing shore power to charge their batteries. Sailing Yacht Salty Lass have one and it is clear that these also require regular, quite time consuming maintenance to keep the insides clean and efficient. Obviously they need a diesel tank (and would normally take it from the main diesel engine tank which we don’t have).

So we are ruling this out for the loss of locker space, the significant electric use (which is what we are trying to avoid) and the amount of maintenance needed.

Drip fed diesel heaters

The brand that seems to offer heaters most suitable for us is Refleks. Their 66MW would fit neatly to a bulkhead which would be safe and not get in the way much. However, there are other options. The 66MV is insulated so it only heats the boat by hot water radiators, we could position that in a custom locker out of the way. The 66MK includes a stove top for kettles etc which would really help cut out electric consumption but I’m not sure where we could fit one. It seems some models can provide hot water for domestic use such as showers but I’m finding the information about which models do that a bit hidden.

As they are gravity fed they don’t use any electricity (I don’t think they even need a pump for the radiators?) and they are supposed to be very low maintenance.

We think at the moment a Refleks heater would be a good option. Whilst it does mean some fossil fuels it is far more efficient to directly heat the boat rather than run a generator to charge batteries to then heat the boat. It also gives a backup heat source should we have a catastrophic electric failure.

Conclusion

By combining lots of these options we hope to get to the point where we can cruise in Arctic summers, stretched Scandinavian sailing seasons and British winters while stretching out the time we can go without needing to connect to shore power.

We will work up to the full combination of insulation, localised heating, wind generation and a Refleks heater (hopefully for radiators in all cabins and hot water for showers) with the goal of being energy independent (with care and some help from the weather) for a couple of weeks at a time. Only time will tell. If nothing else works we can sail to the middle the Azores high pressure and bob around for a few weeks to warm up 🙂

House Battery Bank: Should we go 48 Volt?

While we wrote Going 100% electric: the “house” after Going 100% electric: the Motor we had in fact made most of the decisions around the house electrical system before we made the decision that we would go straight to an electric motor instead of the diesel.

Now we are thinking about making a change. The things prompting us to consider a change include:

  • The high cost of 48 volt battery chargers. We do need the option of charging our battery bank when in a marina or harbour (or even ashore in the boatyard). We can imagine spending sometime alongside in winter or even popping every so often just to get the batteries fully charged (the expectation of needing to live in colder climates in Winter is influenced by both Covid and Brexit which might limit our options for where we spend our time).
  • We think our house battery bank has ended up a bit small (4 x 120AH) and so are going to be needing to charge it from the Motor bank (4 x 300AH) quite often.
  • Having two battery banks at different voltages ends up creating quite a lot of extra complication.
  • With one exception (the anchor windlass) we have realised that our 12 volt usage is relatively low (LED lighting, boat instruments, water pumps).
  • While we have specified really thick cabling with big busbars and fuses, it is challenging to power 2 x 2,000 watt inverters from a 12 volt battery bank. The current that we need to safely pass is huge and this is where the vast majority of our house consumption will be (induction hobs, microwave, multi-cooker, watermaker, water heater).
  • We didn’t understand enough about how you can power 12 volt systems from a 48 volt battery bank. We thought they were too inefficient but have now realised that we either incur that inefficiency when charging a 12 volt battery bank from the 48 volt bank for all house uses OR when using a 12 volt house appliance (but not a mains powered item from a 48 volt inverter). The total losses are much smaller if we incur them only as we need the 12 volt power rather than to keep a whole batery bank charged.
  • We deliberately chose 4 batteries for the house bank that had enough output so they could be re-wired to be a 48 volt battery bank for the motor if the main bank failed. However, it would take ages to do. So a bigger 48 volt bank with two sets of 4 batteries wired in series and then the sets connected in parallel gives immediate access.

So a little maths about the issue with power over 12v cables.

P = power in watts (W)
V = voltage in volts (V)
I = current in amps (A)

Power = Current x Voltage or P = I x V

Switching it around we have I = P / V
So 4,000 watts from 12 volts = 4,000 / 12 = 333 Amps
Whereas on a 48 volt system we have 83 Amps

More amps = thicker cables and lots of care to avoid melting connections or high losses.

The disadvantages of changing from a 12 volt hour battery bank

Our current thinking

  • As we install them, we will configure all 8 batteries as a single 48 volt battery bank. This is pretty straightforward.
  • We will sell our unused 2 x 2,000 watt Victron Phoenix inverters (get in touch if you are interested).
  • We will use our Victron Orion 48 volt DC to 12 volt DC converter to power all our 12 volt appliances. We can always add extra Orion’s to run together if we need more power (eg for the electric auto-pilot)
  • It would be very expensive to add enough Orion’s to provide all the 1,500 watts at 12 volts for the windlass. So we will add a 12 volt battery close to the windlass. When the windlass isn’t being used we can charge the battery through the standard 12 volt system.
  • We will add 2 x 48 volt 3,000 watt Victon Multi-plus charger/inverters (2 of them to provide redundancy, we can run appliances with some limitations off one of them).

The Multi-plus inverters are smart. They provide mains power to the boat circuit and they automatically take that power from a shore power connection or if that isn’t available from the battery bank. When connected to shore power they automatically charge the battery bank. Two of them can put a total 70 amps into the battery bank.

We will have a 48 Volt battery bank with a total capacity of 1,680 AH (4 x 300 plus 4 x 120). Suppose we arrive at a marina with it fully depleted (ie down to 10% charge). That means we need to put in 90% of 1,680Ah which is 1,512 AH. At 70 Amps charging we are talking about 21 hours to fully recharge the battery bank (realistically we would expect many marinas to be limited to either 16A or 32A supplies so this will be a lot slower). Gradually we would expect marinas to upgrade their electric supply as the number of electric boats increases.

While there are costs to this change it does simplify a number of things, particularly with cabling and charging. All our charging goes into the one battery bank without having to switch solar panels between banks or do inefficient bank to bank charging.

It gives us much simpler use of the battery capacity as we can choose how we allocate the available power between house and motor. For example if we are not going anywhere and expect some sunny days in a while we can use all the capacity for the house. Or if we are motoring up a river to a marina all the house capacity is available for the motor.

In the long term we would expect more boat appliances to be available in 48 volt versions which will gradually reduce the need for DC to DC converters.

We haven’t made a final decision on this yet, but it does look like we are heading this way at the moment.

Avoiding engineering calculation paralysis

Two recent examples have in equal measures frustrated and amused me.

In their plans for Ruby Rose 2 Nick and Terysa have oodles of calculations but they appear to be aimed at justifying fitting large diesel engines because an all electric boat isn’t possible. They seem to have totally missed what was shown to be possible in their interview with Dan and Kika from Sailing Uma.

Then there is the subscription website “Attainable Adventure Cruising, The Offshore Voyaging Reference Site” with an article in the last week “Induction Cooking For Boats—Part 1, Is It Practical?” where I joined a discussion coming from our very different approach.

Both these present a numbers based “engineering” approach to decision making about the “practicalities” of moving away from fossil fuels. Sadly due to the initial assumptions the approach almost always leads to the conclusion that renewable energy sources cannot provide enough power for either propulsion or cooking.

The approach rejects working examples because they don’t present numbers in an “acceptable” way.

Our problem with this approach is that it is simply too easy to make assumptions about what is needed and the conclusion depends far more on the assumptions than on the calculations. In both these cases the assumptions are based on the expectations and lifestyle of a couple.

Ruby Rose have assumptions about never compromising on a luxury lifestyle with every modern convenience.

John and Phyllis have decades of experience cruising in high latitudes and strong views on what is safe and seaworthy. They have a stated goal of not considering anything that has not got a 10 year history of reliability.

Both these approaches are flawed if the goal is sustainability (or if budget constraints are tight). So if your assumptions are that you need to motor for an hour at full speed, and 500 miles at cruising speed, cook for a couple of hours every day, run a water maker, washing machine, multiple fridges and freezers, electric auto pilot, video editing laptops every day then you are going to conclude that renewable energy sources can’t cope.

Cynically if you control the list of things that you want to run all the time or anytime regardless of the conditions then you can guarantee that you will never be able to manage with renewable resources (at least until the last oil well has run dry and the Netherlands has disappeared under the sea).

Yet there is another way. One that we find most often from people with limited resources.

Embrace the limitations

Or start at the other end. Start with the resources that are possible.

  • What battery bank capacity can I afford?
  • What size battery bank can I fit (size and weight)
  • How many solar panels can I fit (and afford)?
  • Is wind generation going to fit my boat, my budget, my geography?
  • Is water power generation either from regen on an electric motor or something like Watt and Sea going to work (how much time sailing at suitable speeds)

These provide the constraints. Then sustainability becomes how you live within the constraints. There are plenty of options.

  • A vegetarian or vegan diet (as recommended as a key way of reducing our carbon footprint) can reduce the cooking energy significantly (no a roast chicken cooked for several hours is not required every week, if you want it then save your energy up first, or use a solar oven)
  • Set your passage plans according to the energy you have, probably slower (but then the whole point of sailing is surely to sail)
  • Set your cruising ground according to the season and energy available and required (so you probably can’t sail sustainably into an Arctic winter which is just a constraint, like the ones the majority of people live with all the time)
  • Have food available that doesn’t need to be cooked if you are short of energy (Huel and the like)
  • Plan to use appliances when you have the energy, keep the ones that have to be on to a minimum (eg freezers, fridges, autopilots).
  • Embrace the constraints. Do you really have to be able to do the washing, make water and cook for 2 hours on the same cloudy day – if yes then why?
  • To be honest the list is endless, we have gone in just a few years from it being normal to only use an engine in harbours to expecting to motor constantly for days at a time. From no refrigeration and basic hobs to dishwashers and ovens and drinks coolers in the cockpit.

The argument that it isn’t possible to live within the constraints of renewable energy is disproved by history. It is disproved by the examples already documenting their experiences eg Sailing Uma; and Beau and Brandy.

The challenge is to our assumptions, our privilege, our expectations of luxury. The opportunity is to open ourselves to the impact our lives have on others and to stop seeing ourselves as deserving something that our actions deny for others both now and in the future.

Saturday extra

So we had an extra day this week.

The house battery bank box got the last bits coated in epoxy.

I finished the vertical posts that the corridor and cockpit sides will fasten to. These got coated in epoxy and fastened in with thickened epoxy. They will also support the horizontal beams that the house battery bank will sit on.

Finally, we put the first coat of paint behind the saloon cushions.

Very pleased with the progress this weekend.

Friday progress 24

I suppose the most significant progress is that we has a guest sleeping on board with us for the first time. Stephen, one of our sons, in our social bubble, joined us for the night. The saloon single berth got a good rating.

Today, I ended up working for the morning but Jane and Stephen took the house battery bank apart and then reassembled it with thickened epoxy as glue. They have then coated nearly all of it with epoxy and added some fillet joints to strengthen the joint between the sides and the base.

Then we spent some time going over the design and plans for the electrics.

Meanwhile, one of the lasts part of our drivetrain had arrived (the shaft from the reduction belt pulley to be connected to the propeller shaft via the Aquadrive) so we have been able to lay things out and make sure everything fits (it does – just).

Motor frame on temporary wood supports at approximately the right height showing the motor shaft in about the right position to connect to the propeller shaft.

I’ve had to redesign the way the electric motor rests on the engine mounts so that we can support this shaft at the propeller shaft end. So a few more bits of metal and one extra bearing are now on order.

This shows the base of the box for the motor batteries.

It is slightly oversized at present but there is just space for it and still be able to open/close the seacocks. Access to the Aquadrive (which will be partly under the battery box) will be by making the new bulkhead to the after cabin open-able (after all no carbon monoxide or diesel fumes to worry about).

The house battery bank goes above the motor and the motor battery bank.

The two inverters go on the bulkhead forward of the motor and just above it (grey bulkhead at the bottom of the previous two images).

Given how tight everything is I’m sure we are going to have to pay attention to air flows and ventilation to ensure that the motor, the motor controller and the batteries don’t overheat. However, I’m pretty confident that we are going to be able to make that work fine for most climates with passive ventilation. We will probably need to assist that with fans in the tropics (but if it is hot there should be plenty of solar power available to charge things.

The centre of gravity of the batteries has moved up a little from what I had hoped for. However, I don’t think it is very different to when the diesel tanks were full (and it doesn’t move around). Fortunately, we have saved a whole lot of weight in other places and when we switch to dyneema rigging we will save a whole load of very high up weight.

So not huge visible progress but a lot of thinking and planning will help next steps.

Holiday progress day 9: Electric Motor reliability

Well not much progress today because we nipped home last night as our old Diesel engine was being collected today. The forecast had also helped make the decision with another storm coming through.

So rain nearly all day for the time we were in Manchester, rain for the journey back to Beaumaris and rain most of the evening.

The key progress is emotional, with the sense of freedom from having an engine sitting in our trailer, waiting to be sold. As we were driving back we were remembering all the expensive work we would have had to do in order to get what was a good engine working.

  • The survey required the raw water seacock to be changed. That was bonded in so thoroughly it needed cutting out with a hole saw. Possible with the engine in (although the two cockpit drains would have been much more difficult).
  • the survey warned that the cutlass bearing was worn and that the stuffing box needed to be repacked. We found that the propeller side of the coupling to the gearbox needed to be cut off (and so would have needed a replacement). We also found that the propeller shaft is too long to slide out because of the skeg, so we would have had to lift the engine for the propeller shaft to come out under it, that would have meant cutting off the rusty original engine mounts and replacing them.
  • the survey warned of a leaking fuel filter, would we then have found that several of the valves in the various fuel lines were seized and would we have felt we needed to add inspection hatches to the fuel tanks, replaced all the fuel lines and thoroughly cleaned all the system and all the fuel? As we did that we might have noticed and been concerned about the very rusty fuel vent fittings and the condition of the fuel filler hoses.
  • In this process would we have noticed and dealt with the rusty paraffin fuel tank for the boat heater (that failed and spilt paraffin everywhere just as I arrived at the recycling centre).
  • When would we have taken out the hot water calorifier (heated by the engine or by a mains system condemned in the survey) that was buried behind the paraffin tank, under the rusty fridge compressor and under the unreliable water pump? Because when we did take it out, we found it rusty and leaking out of sight.

In short, because everything around the engine wasn’t replaced with the new engine, we would have had large costs to get afloat with this engine and far more over time to get it to a point where it would be reliable with the many problems with the setup diesel supply (particularly water in the fuel and no way to get it out, modern problems diesel bug growing due to the use of bio-diesel and no way to get it out, old sludge in the tanks causing blockages in the pipes before the filters).

We are more and more glad that we took the plunge and decided to go fossil fuel free from the beginning rather than first fixing what we had. So we have not spent any money on fixing the diesel but all on preparing for where we believe all yachts need to be going – fossil fuel free.

Again we have been watching more YouTube videos and seeing more people having problems with diesel fuel, the old idea that diesel engines are this magical safety device because they are always reliable just isn’t the case for lots of people. Also the amount of nasty, cramped, smelly maintenance and the impact that has on sea sickness and morale needs to be acknowledged more openly in the sailing community.

Obviously, at the moment we have very little to be sure of in terms of the reliability of our electric motor system, how dependable will it be. However, from all we have studied so far we are quite confident. We will have a good installation of a brushless motor, that will be in as dry a place as possible, with potential backup batteries and tools/spares for making cables.

We have come to realise that the Rival 38 centre cockpit has a number of really good features for a reliable electric motor installation.

  • the bilge is really deep and large. So even if we get a lot of water on board it is going to be a long way from the motor or the batteries, we have made this so it is visible for checking as well as making it possible to access the pumps and hoses (initially we are fitting both an automatic large capacity electric pump and updating the original manual pump)
  • the motor compartment is not accessible from the companionway steps (but instead from the corridor to the aft cabin). Very often these steps lift up for access but that also means there is potential for water to get into the motor compartment whether it be from spray or people climbing in with wet clothing etc
  • the motor compartment is large enough so that our batteries, motor and controller can be right next to each other, so short cables that we cann easily inspect that don’t go through bulkheads where they can get damaged or through bilges where they can get wet.

We are also implementing a few things they we hope are best practice to help with the reliability

  • The motor is brushless for no maintenance and high efficiency. It is air cooled to keep our moisture (we will need to monitor temperature and might need exhaust fans)
  • All our battery banks are going to be in boxes that are watertight from below with a top that means any drips from above will not make it in. Build from epoxy coated plywood with a strong timber frame that does not allow battery movement but does allow air circulation for cooling.
  • The motor frame will have a watertight undertray and a lid that directs any drips clear of the motor.
  • Our batteries that are connected in series will have automatic battery balancers to ensure they are evenly charged. Those in parallel will have huge busbars and identical cables for equal loading.
  • We are over specifying all our battery cables and have a full size professional crimping tool to make the best possible connections.
  • Most of the batteries (5 out out of 8) have a bluetooth BMS and I will be monitoring this automatically from our Raspberry Pi system
  • All our solar chargers, battery balancers, battery monitors are from Victron with bluetooth capability so we can monitor them from their app and from the Raspberry Pi system
  • The SignalK system on the RaspberryPi will allow us to add a number of sensors to monitor temperature, humidity etc of everything, so we should know if there is a problem in any battery, bearing, motor, motor controller etc
  • We are installing a dripless seal for the sterntube. This should minimise maintenance and the chance of any salt water coming into the engine compartment.
  • We are installing an Aquadrive. This absorbs all the thrust from the propeller which means the engine and the bearings are free from these loads. It also means that the alignment of the motor is not critical. Both these mean that the motor will be on very flexible mountings so there should be much less vibration in the motor frame as well as in the boat. That should help avoid things shaking loose.
  • We plan to install an automatic dehumidifier for the motor compartment so keep the air in and around the motor plus electronics as dry as possible.
  • The cockpit floor is removable for lifting diesel engines in and out. All our electric stuff is small and light (heaviest individual items under 40kg). Even the motor in it’s frame is under 70kg and we can put it in the frame in the corridor next to where it will go. So we will use a more secure sealant on the cockpit floor, it would be possible to get it up but not as easy as it has been.
  • We will have a much more sealed bulkhead between the motor compartment and cockpit locker. So when you put wet ropes, fenders, sails in there it will drain into the bilge directly and not splash through lots of holes.
  • We are re-routing the vent for the main water tank so it doesn’t go through the motor compartment (reduce chances of water ingress)
  • The boat does not have a working electrical earth at present, we will make sure it is implemented and tested to protect the systems from galvanic corrosion.
  • All new composite cockpit drains and seacocks should reduce condensation and with much higher quality hoses should be more watertight.
  • We are not in a rush and so we can take the time to build it up slowly, carefully and with clear layouts and documentation
  • As we are doing all the work ourselves we know how it is installed and how to maintain it

Despite all that there are still some risks:

  • The biggest is the motor controller, the wiring is complex (for us, fortunately we can bring in our son who is an electrician). Also they are programmable and we don’t have the tools to reprogram it (particularly for regen but potentially also for things like throttle response and max revs)
  • We don’t manage to generate enough electricity to charge the batteries enough (separate updated blog post on generation to come)
  • We do something stupid with one of the expensive components so we need to spend a lot of money replacing it (eg shorting a battery, wiring something wrong).
  • Something we have not thought of

Compared to our lack of understanding of diesel engines this feels like a comfortable place to be 🙂 We think that overall we should be more reliable than diesel, better to live with and because of these be both more convenient and safer than a diesel engine while obviously being incredibly better for the planet.

Going 100% electric: the “house”

I recently detailed where we are at with the Electric Motor, now for the domestic “House” side.

The House power supply

I have started building the battery box which will sit above the motor and motor batteries in the motor compartment.

We have 4 x 120AH Lithium (LiFePo4) batteries from KS Energy KS-LT120B. These have Bluetooth BMS’ which I have been able to connect to from a Raspberry Pi (so one day will be able to monitor and control from the integrated navigation system). Their high continuous current rating of 160 Amp and 30 seconds surge at 250 Amp means they are easily able to power our inverters. It also means that we could rewire them in series to replace the motor batteries if we needed to.

These batteries are going to be connected in parallel so they act as a 12 volt, 480AH bank. This is one decision we agonised over. An alternative would be to have a 48volt house battery bank (and even have a common battery bank for the motor and house – such as Sailing Uma have). The biggest advantage of a 48 volt system would have been for the inverters. However, there are also disadvantages, particularly if you want to add additional battery capacity (you need to add four 12 volt batteries at a time).

Powerful 12 volt inverters require a lot of current, they therefore need very thick cables and short cable runs. Ours are going to be very short and so on balance we have gone for the simplicity of running everything on the house side at 12 volts.

So our batteries are connected in parallel using a massive 60mm x 6mm tinned copper busbar. We will be using very short 95mm2 cables to connect the batteries to the busbar. All 8 cables will be the same length. This form of connection is one of recommended ways (simplest of them in our opinion) of making sure that the battery use is balanced equally across the batteries.

From the battery box +ve busbar we will have doubled 95mm2 cables to a fuse. Then doubled 95mm2 cables to a shunt (used so that the Victron battery monitor sees everything). Then again doubled 95mm2 cables to the main battery switch. Finally the doubled 95mm2 cables go to a +ve secondary busbar at the forward end of the battery box.

From the battery box -ve busbar we will have doubled 95mm2 cables direct to the -ve secondary busbar at the forward end of the battery box.

The reason for doubling the 95mm2 cables is twofold. First, our inverters could potentially draw more current than one 95mm2 cable can carry. Second, the inverters are very sensitive to any voltage drop over the cable (it can cause fluctuations which can damage the batteries). By doubling the cables and keeping the lengths very short we should avoid both problems.

We will have 4 connections from each secondary busbar. All of them will have circuit breakers or fuses on the positive and all of them will have 95mm2 cables to the circuit breakers/fuses.

  • Inverter 1: a Victron 12V inverter giving up to 2000 watts (95mm2 cable)
  • Inverter 2: a Victron 12V inverter giving up to 2000 watts (95mm2 cable)
  • Lofrans Tigres Horizontal Anchor Windlass windlass 12v connected via 70mm2 cables (thicker than the 50mm2 specified by the manufacturer)
  • Distribution busbar for Main 12volt switch panel (busbars situated above the corridor to the aft cabin, switch panels on the bulkhead above the entrance to the corridor)

The 230volt AC systems

The Victron inverters get connected together into a single mains supply. So we have a 230V 4000watt mains supply via a standard circuit breaker box. The main purpose of having so much 230 volt power is the galley. In the galley we have

  • 2 x single induction hobs (max 2000watts each)
  • Microwave/combination oven/grill (max approx 1000watts)
  • Multi-cooker (max 900watts)

And no doubt we will be adding coffee machine and a few other gadgets.

So we will be able to run any 2 of these devices at full power at the same time (and to be safe we won’t run both hobs on full power at the same time).

Beyond the galley we have

  • 230volt water heater to supply sinks and shower
  • Device like our current laptops which only have 230 volt power connectors.
  • Two wall infrared panel heaters.
  • Power tools (most of them are now cordless but the batteries are charged from 230volts)
  • One day in the future a 230volt watermaker

Our electric outboard motor for the dinghy has a 12volt charger as well as a 230volt one.

4000 watts should be plenty with some simple house rules

  • only one cooking device while using the windlass (why would anyone be cooking when you are either raising or lowering the anchor?)
  • if using two cooking devices then turn off most other mains devices (possibly via the circuit breaker?)

The 12volt DC systems

These are mostly very normal for boats with lights, instruments, electric autopilot (we mainly want to use a windvane anyway), fridge (not planning a freezer), windlass (a lot of current but not for very long).

However, we are also going to be building our navigation, entertainment and office systems around 12volt Raspberry Pi computers and 12 volt screens. This will include WiFi to our phones etc. We will be fitting a hi power/long range 3G/4G antenna that will make it’s connection available via WiFi to everything else.

The Raspberry Pi’s will be used for navigation (we have a touch screen for the cockpit) with OpenCPN as well as for general use (everything from NetFlix to general office to video editing) on a TV screen in the saloon.

We will be using a SignalK server to connect the Raspberry Pi systems to marine instruments (AIS, Radar, WindSpeed/Direction etc). Anyway that is a whole lot of other posts.

Capacity

While it is perfectly ok for us to plan the system so that we can deliver 4000watts for cooking at full power on two hobs or run all these other devices the fact is that we still have a battery bank with limited capacity.

Here we admit there are a lot of unknowns and variables. However, we think that being able to monitor our battery use very accurately will allow us to modify our behaviour to suit the available battery charge (eg no hot showers or minimise cooking power use).

The next key part of the picture is how we recharge our batteries, both house and motor banks). That will have to be a separate blog post.