The Electric Plan: Solar

So in my last post on Introduction to generation I outlined the options and challenges for renewable energy generation and concluded that we were going to start with solar.

This video from Desiree and Jordan, Project Atticus, has been helpful. Like us they have a ketch (although smaller) which means a radar arch doesn’t work.

The simplest first step is going to be 4 x 40w solar panels on the top of our wheelhouse. It has a perspex “window” slot in the middle to allw you to see the mainsail when steering. That restricts things a bit but we can essentially fit one 40watt panel in each corner. Hopefully only one side at a time will be in shade from the boom & sail. So the panels will be connected in series along each side and then the two sides connected in parallel. That way the shaded side doesn’t affect the output of the other side. These will connect using a single Victron MPPT controller to the house battery bank.

The second step is to setup 4 large 175watt panels. They are approximately 1.5m long by 0.7m wide. We are starting with 2 controllers for these (one per side of the boat). The intention is to do some experimenting and end up with a variety of places they can be setup depending on whether we are at anchor or in a marina or sailing.


We are going to fit legs to the middle of the short sides. The bottom of the leg will be fixed just inside the edge of the boat. So the panel can be “stored” vertically or it can be swung out and the angle adjusted for maximum effect. They probably will need to tacked with the boat so that on the downwind side they don’t hit waves (ie we fold them away on the side we are heeling towards). At anchor they can be fully deployed and should get minimal shading. They will go from the back of the boat forward about 3m which should mean they are clear of where we get in and out of the dinghy as well as clear of sheets (the ropes that control the sails) when sailing. We probably won’t be able to use them when tied up in a marina as they will either overhang the dock where people walk or be in the way of other boats. We will make them reasonably quick for us to remove so that we can put them in other positions when that will be more effective.

Mizzen Boom

When we are anchored or in a marina they should fit across the boat while resting in the middle of their length on the mizzen boom. Not quite sure what will be the easiest way to fasten them here as the legs won’t be quite as long as the boom is high.

Stern Gantry

I haven’t quite given up on putting panels off the back of the boat. It would require a “goal post” that is clear of the swinging boom (and sufficiently braced). I’m thinking the panels would need to be able to slide either behind the boat (when using the mizzen) or forward (blocking the mizzen but out of the way for docking).

Wheelhouse Sides

I’m not sure if this can be made practical enough. I was wondering about fitting one long edge to the top side edge of the wheelhouse and then supporting the panel to stick out horizontally. They would not stick out much beyond the side of the boat but you would have to duck under them to walk forward and they might catch on ropes (particularly jib sheets).


The 4 x 40watt and 4 x 175watt panels we have at present should give us 860watts which is a good start, although we have to assume that due to shading we will be looking at more like 400watts effective at any particular time (depending on whether we move the big panels around when on anchor).

If tests show that all the places I’ve mentioned are possible then we might be able to get to over 1,500 watts which would be awesome (and enough to start considering an electric motor).

Beyond that if we can sort out storage when not in use we could potentially fit another 4 around the sides of the boat when at anchor.

By this time traditional conservative sailors are going to be horrified about what Vida will look like 🙂 To us though not needing fossil fuels is incredibly beautiful and very worthwhile.

To facilitate the flexibility we will end up with a variety of connection points around the boat supported by multiple MPPT boxes. Until then we will experiment using longer extension leads while we work out what works best.

One of the big challenges is that most of the examples (on YouTube that includes channels like Sailing Uma, Project Atticus, Beau and Brandy Sailing, Rigging Doctor) were at least started in the tropics where the experience of the sun is quite different to North Wales. We need more panels and we need to angle them more efficiently than they do.

We also need to focus a lot of attention on minimising the use. Having a large battery bank and big inverters needed for induction hob cooking could tempt us to be heavy electric users meaning we will never be able to generate enough renewable energy, I’ll be writing about that side of the equation too.

The Electric plan: Introduction to generation

This is probably the most important element of the electric picture. If we have to generate electricity using fossil fuels then all we have done is move the fossil fuel from one source and time to another. On the other hand if the electricity that we store comes from renewable sources then we can look at fossil free cooking, cooling, heating, lighting, navigation, dinghy outboard and one day full engine power for the whole boat. You can see by the number of those areas without links how much more writing I need to do.

On-board renewable energy generation

We are starting from zero here. Nothing on the boat at all and no supporting infrastructure (cables etc). There are 3 main sources of renewable generation commonly used on boats. Solar, Wind and Water. Sadly our boat has shortcomings when it comes to all of these which make it all rather challenging.

The challenges


Until I started researching solar panels for boats I didn’t realise the impact of shadows on solar panel performance. It takes very little shadow to reduce the output of a whole panel (or even a whole series of panels connected together) to almost zero. Unfortunately sailing boats have a whole load of shadow creating rigging (masts, booms, stays, sails, sheets) and other equipment (radar, aerials etc).

Also we all know that solar panel efficiency is greatly affected by the angle of the panels to the sun. Again this is tricky on boats as they roll, heel and change direction.

Finally, solar panels become less efficient if they get too hot. So fixing them to a flat surface (such as a cabin top) without ventilation reduces the efficiency (but adding ventilation means that you have strength issues if they are in places where you need to walk).

The easiest boats to add lots of solar power to are catamarans, as they are so much wider they have huge areas of deck space (and large cockpits that can be made more comfortable by adding shade from solar panels). We don’t have a catamaran (and not because we would not have liked one, just they are way outside our price range for purchase, maintenance, storage and mooring).

When it comes to monohulls then the most common solution is to build a “radar” arch across the stern and mount solar panels on this (sometimes with the option to tilt them to face the sun). See this video from the wonderful Kika and Dan on Sailing Uma for how they did it (first time around).

Unfortunately, even here we have extra challenges. As a rather traditional design our Rival 38 has many advantages when it comes to seaworthiness, however, compared to modern boats the stern is quite narrow which restricts the size of panels that can fit on a “radar” arch. Also, Vida is a ketch so we have two masts and rhe mizzen mast is set well back with a boom that extends to the very end of the boat. That means that any solar arch would need to be a gantry extending out beyond the end of the boat. The structural challenges are not too great but there are implications on the cost of moorings and storage (typically charged by length) and it would likely be vulnerable to damage in lots of situations.


Using a wind generator seems obvious on a sailing boat. They too are not without their challenges (and again our boat makes some of these more difficult).

  • Power: They work best in stronger winds. However, generally by choice you anchor in sheltered places protected from the wind for comfort, exactly the opposite of what you need for effective wind generation. When long term sailing the goal is typically to sail downwind whenever possible (much more comfortable and faster). When sailing downwind the apparent wind speed is reduced (true wind speed less boat speed) often making wind generation ineffective.
  • Mounting. Again our mizzen mast makes things more difficult. We can’t just mount a supporting pole on the back of the boat as our mizzen boom sticks out so far. This doesn’t just affect the vertical pole but also the supporting braces. One option with a ketch is to mount the wind generator on the mizzen mast. Typically on the front about 1/2 way up (exactly where our radar is at the moment and where it would get snagged on the potentially very useful mizzen staysail). Another option is on top of the mizzen mast which keeps it well out of the way of everything including me when it needs maintenance (as the boat rolls the top of the mast moves pretty dramatically which puts a lot of strain on the wind generator and means that it is moving rapidly which affects it spinning).
  • Noise: Wind Generators have a reputation for both noise from the spinning blades and from vibration echoing through the supports. Not great for us as our main sleeping cabin (at least when we are not on passage) is the aft cabin which has the mizzen mast stepped on it and where the braces for a pole at the stern of the boat would be mounted.


In recent years water generators have been gaining popularity. Essentially they look at little bit like an outboard engine with a propeller on a shaft off the back of the boat. As you move the water spins the propeller which generates electricity. For us a couple of concerns. One is whether we can sail fast enough to generate much power. Second is that there isn’t a lot of space on our narrow stern, especially if we end up with a windvane self steering (which would probably reduce our energy consumption by more power than the generator would add).


Initially, we are going to try to break all records for the amount of solar we can generate given the challenges we face. That will include us moving the panels dynamically to try to make the most of them. More in a later post.

The Electric plan: Storage

Our Electric cooking plan and the need to charge our Electric Outboard (plus other projects) has made it obvious that we will need a big house battery bank. On boats there are typically separate battery banks for engine starting and domestic/house purposes. The intention being that even if you leave all the lights on and flatten the house battery you will still be able to start the engine. That was especially important when the engine alternator was the only way of charging your batteries.

The house bank on the boat as we bought it was made up of 3 lead acid 12V batteries that had been left alone for more than 12 months. They will hold enough charge for using a interior light for a short while but no more than that.

There is now a ton of evidence that it is most cost effective on a boat to buy Lithium-ion Phosphate batteries. They have numerous advantages over older technologies including:

  • Easier recycling of the Lithium
  • They can last orders of magnitude more discharge/recharge cycles than any other battery technology
  • They can be discharged to around 90% without damage, unlike lead acid which can can only be discharged to 50% before needing to be recharged.
  • They can be discharged faster for high power applications
  • They can be charged much faster
  • They are lighter
  • You can add new batteries into a bank of old batteries (can’t do this with lead acid etc)

So looking around there are many people building battery banks from a variety of non-marine specific batteries (mainly due to the price premium charged for “marine” batteries). Also many people are building battery banks from lots of smaller batteries eg 6volt golf cart buggies, for similar reasons.

When building a battery bank one of the absolutely key decisions to make is what voltage you are going to configure the bank as. For example two 12 volt batteries can be connected in series to appear as a 24volt bank or in parallel to appear as a larger 12volt battery. You get the same total capacity but if the voltage is higher you get the same power from lower currents.

For example if I want 2,000 watts for an induction hob then from a 12volt battery I will need to draw 166 amps of current (ignore the conversion from DC to AC at the moment). That is a lot of current and will require a very thick cable if you are not going to melt it or have very low efficiency. With a 24volt battery the same 2,000 watts will only need half the current: 83 amps, so the cable can be thinner and cheaper and easier to install.

From this logic the temptation is to go for the highest voltage bank of batteries that you can. For electric motors, used instead of diesel engines to move boats (the most power hungry of all devices), the battery banks are often 48volt or even 72volt. However, there are disadvantages too. 48volts is into a new level of dangerous if you get it flowing through you. From here “In industry, 30 volts is generally considered to be a conservative threshold value for dangerous voltage. The cautious person should regard any voltage above 30 volts as threatening, not relying on normal body resistance for protection against shock.”

Then there is the matter of how you configure your batteries to create a bank. To get a 48volt bank from 12 volt batteries you need to connect 4 batteries in series. That means you can only extend your battery bank by adding 4 extra batteries at a time. A 72 volt bank needs batteries adding in sets of 6. A 12volt bank allows you to add one 12volt battery at a time.

Also we need to consider what the battery bank is powering and where it is situated. In our case most DC devices for boats are 12volt (many are now also available in 24 volt but not stocked as widely and more expensive). For us the big power devices are going to be AC at 240 volts. The AC power can run through much cheaper power cables. That just leaves very high levels of current running to the inverter before they get switched to high voltage AC. We can minimise this problem by keeping the inverter close to the batteries and using big cables, also by using multiple inverters so that the current gets split between them.

So we have gone for a huge 12 volt battery bank with three big 300 ampere hour batteries (traditionally 12 volt batteries have been about 100 ampere hours). This is slightly cheaper and significantly simpler to install than 9x100AH batteries. I’ll be using very thick, oversized cables between the batteries and to/from the inverters to minimise the losses. We have gone for a pretty low profile brand at about 2/3 the cost of better known ones as a calculated risk.

Will let you know how we get on when they arrive.

The Electric plan: cooking

As the entire gas system (used only for cooking) was condemned by the surveyor we are taking the opportunity to try eliminating another fossil fuel. So we are going electric for cooking.


Fortunately, there have been huge advances in electric cooking in recent years. So we are having two separate one burner induction hobs. Having separate hobs means we can run both at full power and also means we have redundancy if one fails.

So our batteries will feed two inverters. These can work together so while each one converts 12 volt DC into 230 volt AC with a maximum of 2,000 watts we can draw a total of 4,000 watts at anytime. With modern inverters the loss of efficiency in converting from DC to AC should be less than 10%, including the cables.

We have been using and measuring the power used by the induction hob. While the draw on high power is a lot, the total isn’t because they are so efficient and fast.

We are having to refit the galley area anyway so we will be creating a gimbled “tray” for the hobs. That means that when the boat rolls the hobs swing and the food stays in the pots.

Other cooking

We are going to be experimenting to see what we feel really adds value when it comes to cooking, possibly a microwave or a small oven. Possibly an instant hot water boiler (safer than using a kettle). Again high power for short periods of time should be achievable.

We will also be looking at Solar ovens (although not with high expectations while we are in the UK).


The obvious challenge is to make sure we have enough electricity stored and enough renewable energy generation to keep going. So I’ll be writing separately on these topics.


As with the dinghy engine the key advantage is the elimination of another fossil fuel from the boat. However, more than that it is long term freedom from having to keep finding new gas cylinders. The typical Camping Gaz bottles used in the UK are not available all over the world. There should also be cost savings as once everything is installed there are no fuel costs.

Plus there is the ease of cleaning and the much better cooking experience of induction hobs.


In the past electric cooking has only been for superyachts or powerboats who run engines or generators the whole time. However, with advances in every direction (generation, storage, conversion, efficiency) we know that there are a few boats already doing this and we feel that it is only the traditional conservatism of the sailing community that hasn’t led to widespread adoption yet. Given the climate emergency it is a change that will need to come fast.

Dinghy cradle

So Highfield provide a pdf download plan for a cradle to store your dinghy so that it is under least stress.

I’ve just knocked up one using the wood from the pallet that our solar stuff arrived on. It isn’t going to win any prizes but should be practical enough. The intention is that the cradle will fit in the van to make carrying the dinghy easier (the front section might need to be lifted a bit so that the front of the dinghy will fit between the front seats).

I’m going to add some rubber padding and if it works in the van will paint it so that it lasts a bit longer.

The Electric plan: Outboard

A key element of our goals for Sustainable Sailing (as we have hinted at many times) is going to be replacing fossil fuels with electricity with the assumption that the electricity comes from renewable resources. So this is where we are at so far:

Outboard Engine

Vida didn’t come with an outboard engine or a dinghy (at least one we think is suitable). So we have gone for an electric outboard. In many ways it seems like an obvious option. There are many obvious advantages of electric outboard motors to power a dinghy to make getting to and from the shore easy.


  • Replaces petrol with (renewable) electricity. The key and obvious win, should be enough reason on it’s own. We have to massively switch away from fossil fuels as an essential response to the Climate Emergency.
  • More portable. Compared to a petrol outboard engine this is so much easier to move. The battery is removable and so you end up with two parts that are both light enough for me to easily lift on and off the boat, in and out of the van, up and down the beach.
  • No spills or smells. Petrol outboard engines smell, the fuel tanks smell, spills smell. Petrol gets split and smells. Electric outboards have none of these issues. you can keep them anywhere in the boat without worrying about spills, they don’t have to be kept the right way up. You don’t have to make sure you have used up all the fuel in the carburettor to avoid spills.
  • Safer. No risk of explosions or fire! Petrol in enclosed spaces (like a locker, or in your vehicle travelling) is explosive.
  • More reliable. Petrol outboards are notoriously high maintenance and unreliable. Always needing servicing.
  • Simpler and easier. No difficult pull start, just turn on and twist the throttle. To reverse just turn the throttle the other way. Full torque immediately available without any need for chokes or warming up.
  • Waterproof. The battery actually floats, not just waterproof but if you drop it in the sea it will float! Compare this to the hours of video on YouTube of people having to rebuild their petrol outboards if they get dunked.
  • Silent. Especially useful for when we arrive late at night. We will be able to get our to the boat without disturbing anyone else.
  • Zero maintenance. Comes with a promise of being Lifetime Maintenance free


  • Speed. We are not going to be able to go anything like as fast as would be possible with a petrol outboard. The maximum size of engine for our dinghy is 15hp which will comfortably plane, the recommended size of 10hp will also plane if not fully loaded. Without paying silly money electric motors max out at about 3hp equivalent. So we will pootle rather than zoom. The only issue for us is the speed of the tide in the Menai Straits which will run faster than we can motor. We will just have pick times carefully or hug the shore to avoid the main tide.
  • Range. Essentially unlimited with a petrol outboard as you can always carry extra tanks of fuel. With electric once the battery is flat you are stuck until you recharge it. The range at full speed should be about 6 nautical miles (7 miles, 11km) which can be doubled by slowing down. We are giving ourselves some comfort space by having a 2nd battery, also by having both a fast mains charger (that we can take ashore to charge at almost anywhere) and a DC charger that means we can charge efficiently on the boat.

So we have bought an Epropulsion Spirit 1kW unit with extra battery from Nestaway Boats, doing so before the recent plummeting pound was reflected in the prices. We haven’t yet used it yet so more when we have. Meanwhile have a look on YouTube to see plenty of positive experiences.

Aft head update

So here is a video of where we got up to last weekend with the aft heads.

The Natures Head composting loo needs a bit more space than the original Lavac pump out loo, in particular it is quite a bit taller. However, the seacock under the floor is no longer needed (was toilet flush inlet) which is good as the access is rubbish and the bolts look like they need replacing (and they are not cheap).

So by removing the flush inlet seacock (and properly filling the hole with epoxy and glass cloth) we can lower the floor for the new toilet. Obviously we can also remove and fill the toilet outlet seacock. Now we are thinking that it would be good to also get rid of the sink drain as that will allow us make the compartment feel more spacious (or at least make it a bit more comfy), plus it means one less seacock to maintain, one less potential leak. We are doing some research on how we might combine basin & sink wastes.

We wrote about seacocks in a lot of detail at Refurbish or replace: Seacocks? since then I’ve upped my aims. My goal now is to have only 3 holes below the waterline (2 cockpit drains and one engine inlet). Above the waterline there I’d like just 6 (4 x deck drains, engine exhaust and a multi-use bilge pump out).

The video starts talking about the electrics which are going to be key to our reducing the fossil fuel use. Much more later!