Electric liveaboard catamaran project

I've bought a boat!

It's a 1976 Catalac 9M catamaran, older than me. Now it had two 30HP perkins diesel motors. These were completely overpowered for a sailboat like this, they usually have two 10HP diesels. They're also really heavy, and smell like diesels. This is a major problem for my wife, as she is part bloodhound and would simply not live on a boat that smells of diesel.

So the diesels have been removed, along with the gearboxes, shafts, and propellors. Then as I like things simple, I've decided to replace them with two 6kW ePropulsion outboards. This also frees up a huge amount of space in the giant engine bays that I have other uses in mind for.

Then in terms of batteries I'm thinking of a 16S1P pack of Eve 280AH cells or similar for just over 14kwh of power. I could be persuaded to go for a 16S2P or two 16S1P packs, which would increase range, but I'm tempted not to as I think the 1P pack would be enough battery for my typical use, and I like the idea of lightening the boat somewhat. Another option would be to put a Yamaha 9.9 outboard for added range/redundancy, but if that can be avoided I'd rather do that.

To keep it all charged my plan is for somewhere between 2800w and 3600w of solar, made up of between seven and nine Sunpower Maxeon 3 400w panels. These will be all in parallel to avoid shading issues, and run to three 48v Victron Smartsolar 100/20 MPPT charge controllers.

From someone I know with a similar boat, he gets around 5 knots on 2500 watts of power, so in good sunlight I could motor a very long way and still have power for using at night. When not motoring, the large battery pack will send power to a 48v inverter, to give my wife some of the creature comforts of home, such as hot showers, a washing machine, and all the electricity she wants for other things.

In our current apartment we use around 10kwh per day, and the amount of panels on the boat should support that on non-motoring days.

The 12v bank will be a 4S1P pack of the same batteries, charged by a DC to DC.

I've attached some pictures, but note that they're 3+ years old from before the boat was stored on land, so it's quite a lot worse for wear. As I plan to live onboard I'm willing to put in the time and money to get it back into even better condition again.

Happy to hear your thoughts, and if you have any better ideas on what to do.

Nice boat !.... i have happy memories of living on a cat ..more than a few years ago !
I dont know where you are based , or plan on going to.....but if you are happy to rely on the sun for motor power etc, then you should consider using direct solar water heating also .
Many experienced free campers have found that hot climates generally heat water more than enough for showers, washing etc, even without a managed defined solar heater system.
It is not sensible to waste solar generated electricity on a water heater ! .

So just one quick update. I was able to spend another week on the boat and get the first piece of the project done... The engines are out! It was a monumentally difficult job due to the hardtop making it impossible to use a crane, and the boat being out of the water, over 2 meters above the ground. Fortunately the previous owner was around again, and was hugely helpful. He designed a crane we strapped to the cockpit and the very strong rear arch with a manual winch to lift and lower the motors.


I also think I've decided on the solar layout. It'll be for 3.2kW of panels, all in parallel to minimize the effects of shading, with two panels per mppt controller.


I'll only be back at the boat in April so between then and now it'll be a lot of research, ordering components and watching videos on how to work with fibreglass. If anyone has some good resources on that please let me know.

patrickza said:

I'll only be back at the boat in April so between then and now it'll be a lot of research, ordering components and watching videos on how to work with fibreglass. If anyone has some good resources on that please let me know.

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Nice boat project!
Have you already bought the electric outboard motors? If not, you could look into the QS Motor range to replace the diesel engines. More info on them here on E-S:https://endless-sphere.com/forums/viewtopic.php?f=31&t=65972

Water cooled QS138 is probably more than enough:https://nl.aliexpress.com/item/1005002741157530.html

QS180 motor:https://nl.aliexpress.com/item/1005003493746855.html

Ref solar panel rating... remember you will not get near the full panel rating with them mounted horozontal, and when you are under way with sail and wave motion, the output is very erratic.
A wind generator can be very effective on a sail boat..and at night !

I have been pondering the idea of getting into sailboats or should I just say "boats" because I'm not exactly sure which direction I'd end up with. (big, small, single hull, cat or tri)

There are very well done ENTIRELY solar boats. Catamarans seem to be the preferred shape.

If you do the math on it you could just dump the sails and make something that can go great distances at a slow pace entirely on the sun. And with enough battieries (60kwh) you could run at night too.

Just look at your boat... you are covering maybe a third with solar and getting 3200 watts. (3.2 kwh)

Do the whole thing solar and what do you get? 10 kwh.

So if you get six hours of good sun per day you recharge the battery.

Run the motor at 2500 watts and move along at 5 knots. (60,000 / 2,500 = 24 hours)

For emergencies you have a back up generator to add charge.

And most docks have electrical plugs so you could jump from dock to dock while touring.

SafeDiscDancing said:

If you do the math on it you could just dump the sails and make something that can go great distances at a slow pace entirely on the sun. And with enough battieries (60kwh) you could run at night too.

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The wind gets you a lot more motive power for a lot less work and money. I'd hesitate to give that up. (And the wind can even charge your batteries from your forward motion if your drive is set up to do that.)

Just look at your boat... you are covering maybe a third with solar and getting 3200 watts. (3.2 kwh) Do the whole thing solar and what do you get? 10 kwh.

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Right. Now look at sails.

If you have 60 square meters of sail, and are making 10 knots in a 20 knot wind, you're generating about 45 kilowatts of motive power. And that works day and night.

A hybrid of both is pretty ideal.

SlowCo said:

Nice boat project!
Have you already bought the electric outboard motors? If not, you could look into the QS Motor range to replace the diesel engines. More info on them here on E-S:https://endless-sphere.com/forums/viewtopic.php?f=31&t=65972

Water cooled QS138 is probably more than enough:https://nl.aliexpress.com/item/1005002741157530.html

QS180 motor:https://nl.aliexpress.com/item/1005003493746855.html

Click to expand...

Outboards aren't bought yet, but while an inboard may have some advantages, I'm going for a boat with no holes below the waterline. The head will be composting, and with outboards I can close up the shaft tube too.

SafeDiscDancing said:

I have been pondering the idea of getting into sailboats or should I just say "boats" because I'm not exactly sure which direction I'd end up with. (big, small, single hull, cat or tri)

There are very well done ENTIRELY solar boats. Catamarans seem to be the preferred shape.

If you do the math on it you could just dump the sails and make something that can go great distances at a slow pace entirely on the sun. And with enough battieries (60kwh) you could run at night too.

Just look at your boat... you are covering maybe a third with solar and getting 3200 watts. (3.2 kwh)

Do the whole thing solar and what do you get? 10 kwh.

Click to expand...

I would get around 10kW covering the whole boat, but it's hard to go back from that. I suspect the mix of sails and solar will do very nicely for my needs, but I'm not ruling out a phase 2 if it turns out I hardly ever sail.

Hillhater said:

Ref solar panel rating... remember you will not get near the full panel rating with them mounted horozontal, and when you are under way with sail and wave motion, the output is very erratic.
A wind generator can be very effective on a sail boat..and at night !

Click to expand...

I'll look into it, but for the start I'll go pure solar. I know someone with a similar boat, and he moves along nicely with 1kw of power, which I should get fairly easily.

patrickza said:

Outboards aren't bought yet, but while an inboard may have some advantages, I'm going for a boat with no holes below the waterline.

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Although a project on its own, I love the EV conversion of an outboard motor "goatman" is doing for his Bayliner:
https://endless-sphere.com/forums/viewtopic.php?f=39&t=107045&start=100

There seem to be a lot of ready made electric outboard motors available these days:
https://www.elcomotoryachts.com/product-category/electric-outboards/

https://www.edyn-marine.com/product/1018-ob-edyn-lithium-battery/

patrickza said:

I'll look into it, but for the start I'll go pure solar. I know someone with a similar boat, and he moves along nicely with 1kw of power, which I should get fairly easily.

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The bottom line is whether you are in a big hurry or not.

And it also depends on where you plan to operate the boat. Sunny Florida or some place less sunny.

Probably the wisest move is to install a motor of sufficient size to get you out of trouble when you have no choice but otherwise in calm conditions to operate at low power most of the time.

If a hurricane were heading straight at your boat you need the ability to rapidly get out of the way.

A large battery is a safety measure to guarantee you get away.

Whatever you decide to do is great and I love the idea and have been thinking about it for a few years... might do it someday but I'm kind of stuck in place for family reasons for now so I'm not free to leave.

patrickza said:

Outboards aren't bought yet, but while an inboard may have some advantages, I'm going for a boat with no holes below the waterline. The head will be composting, and with outboards I can close up the shaft tube too.
............
..... but for the start I'll go pure solar. I know someone with a similar boat, and he moves along nicely with 1kw of power, which I should get fairly easily.

Click to expand...

Before you finally commit ...
Have you sailed a Cat with outboard drives before ?
Unless you plan on staying in rivers or lakes, the pitching of a cat in open water waves will lift a transom mounted outboard prop clear of the water.. they need to be mounted as far forward as possible.
..and i would not venture into open water with only 1 kW of power..unless you are a very confident sail boat user.
You would need much more than that to move safely in a tidal or river current..let alone against a headwind.(Catalac has a lot of freeboard windage )

Hillhater said:

Before you finally commit ...
Have you sailed a Cat with outboard drives before ?
Unless you plan on staying in rivers or lakes, the pitching of a cat in open water waves will lift a transom mounted outboard prop clear of the water.. they need to be mounted as far forward as possible.
..and i would not venture into open water with only 1 kW of power..unless you are a very confident sail boat user.
You would need much more than that to move safely in a tidal or river current..let alone against a headwind.(Catalac has a lot of freeboard windage )

Click to expand...

I won't be fully committed until I punch in the credit card numbers

I must admit, I do quite like Justin's new marine kit... I'm going to speak to him and see what it would take to connect a couple of his big marine motors to each of my shafts...

Quick update:

I've ordered 24 Eve 280AH cellsand will be making the following:
-1 x 16S1P pack for the propulsion motors and 48v inverter
-1 x 4s1P pack for the house battery
-1 x 4s1p pack for a trolling motor for the dinghy

I'm looking at a Haswing Protruar for the trolling motor, probably the 600w 1.0. The 280AH batteries are overkill for this motor, but it will definitely give me a great range!

For the propulsion motors I've ordered two ePropulsion Navy 6.0 Evo outboards. In the end the allure of having no holes below the waterline, and the ability for me to service things without taking the boat out of the water won over the pod drive motors being deeper in the water. It took a huge amount of back and forth in my head, and I'm still not 100% sure it was the right choice, but it's done, so I'll have to make the best of it. It is a sailboat after all, so theoretically I'll sail faster without the drag of the motors in the water.

Then I've decided on the following layout for the solar panels:


That'll give me 3200w of mounted solar. Every panel will be in parallel running to four Victron Smartsolar 100/20 48v MPPT controllers. That will hopefully give me good resistance to shading. I suspect that on non-motoring days I'll have plenty of power. At my house at the moment we only use 10kWh per day on average, and the solar calculators tell me I'll produce more than that on a typical day, at least in summer.

On motoring days I'm hoping to be able to move using zero net energy when the sun is strong. Once I've done some decent testing I will decide if I'd like to double the battery pack size, or go for a Honda 22i generator as backup power. At the moment I'm leaning towards the Honda, mainly because it'll be significantly lighter, but also because it will allow motoring regardless of the weather.

Then for one last update of the electrical nightmare! Here's the before:


This is what I removed:


And this is me probably just past the halfway mark


And what a nightmare it was. The boat had no tinned wire, positive and negative busbars hanging protected only by painters tape, crocodile clips connecting to wires, wires changing colours mid way through, everything in blue brown and yellow, both AC and DC. Rusty chocolate block connectors, no ferrules anywhere to be seen. All solid single core house wiring for the AC. It was a nightmare, and a fire waiting to happen, though the heavily corroded through hulls and non functioning bildge pumps would have sorted that out in no time

Now it has bright yellow tinned Lapp arctic cable for the AC (not in picture) and tinned Oceanflex for the DC. All the breakers are DC rated, and all well under the amperage that the wire can handle. I'm prett clse to finished with the AC wiring, and the DC is around halfway I think.

It works!!!


Still a few more things to work on, including making it sail, but at least the electrical and propulsion systems work!

Well done!

Thanks, it was a very stressful project. Right until the last minute I still had no idea the boat would float

Okay so after my first season which included a full month at anchor I'm really pleased with the boat. There were only two negatives. First, I never got the sails setup, so I just had a motorboat, and secondly, I was terrible at docking!

In total I had around 20 long motoring days, where I averaged around 25 nautical miles a day. I would typically start the day on 60% battery from my overnight usage, then set my motoring speed to use all but 500w of the solar power, so in the morning that might be 500w going to the motors, and 500w going to the batteries. Later in the morning I would send 1000w, then 1500w, and then 2000w to the motors which gets me to 4.5-5knots of boat speed, while still charging the batteries at 500w. Then as the solar increased I'd just let the extra power go into the batteries until they were full. Once that happened I'd put all the power into the motors for an extra half a knot or so.

This meant I got to my destination with a full battery back, so I could run the water maker if needed, the water heater for our showers, and I could use the microwave and electric stove for dinner.

It worked brilliantly. I'm hoping next year with the sails I'll be able to either sail or motor sail a little faster.

The docking wasn't fun. It seems my motors are too close together to be able to use differential thrust to "tank steer" the boat like I use to on other catamarans. I also don't have water flow over the rudders, so if the boat wasn't moving it was very hard to steer. At the moment my solution to this for next season is to have a docking setup for angling the motors toe in like this:

I'm hoping that will mean I can use either motor individually to pull the boat in that direction like a typical outboard powered boat with steering, or that I can now use "tank steer" using both together more effectively. Any thoughts on this?

I have a 37' ketch with only an eight foot beam. It had originally had two 5hp gas engines driving two props, but someone had replaced them with a single 27hp diesel. Given that the diesel needed replacement I decided to mount a pair of 9.9hp electric outboards.

They were only four feet apart, and forward on one and reverse on the other didn't have enough offset to turn the boat.

So a I added steering cables, using stick steering, mounted to the aft wall of the cockpit. With the motors turned my boat will spin in its own length.

You might check out the Wynn's on youtube. They are having a hybrid 45' built in France. I believe that their only $ comes from their channel.

Patrickza- nice project! Really good to hear about solar panel performance- especially range. It’ll be interesting to know how much speed prop regeneration lowers sailing speed.

We just converted our monohull sail boat from a Yanmar diesel to a Torqeedo 48-5000 for the Torqeedo Saildrive, and 2 Torqeedo 24’s for the housebank. A few things we’ve learned-

As far as docking- epower has changed docking from a hideous terrible emotional thing to something positive- the nice thing about edrive on a boat is the nearly instantaneous torque (response) from the props. This means you can glide without power into the slip in neutral at whatever is just above the threshold of positive steerage (a couple of knots), ready to go into reverse to stop the boat (which will happen quickly with epower). If you have centerboards or daggerboards, they need to be down to try to prevent sideslip. It really helps if you can helm (and use the throttles) from a spot as close to the side of the boat next to the dock, so you can judge how close you are. Using BIG fenders will help. Lateral distance to the float from your boat is crucial, whether by eye, or from your crew by hand signals or verbally. With epower things are nice and quiet. Stick the boat 1/2 way or so into the slip, stop, get off, and walk her in.

Backing a boat out can seem tricky- go as slow as you have steerage, but not a lot faster, or the rudders will do all sorts of evil things. A crew can start moving the boat out to get things started, and then hop on. Keep things gentle.

You can practice all this away from the dock with a lifejacket thrown in the water. Communication of information is crucial, not yelling. Figure out what you need to know. Nobody needs to yell. Epower is nice and quiet.

You’ll need to learn what current and wind do to your boat at low speeds.

As you’re getting the sailing part of the boat together, keep in mind that windward performance is incredibly important in an electric sailboat, mainly because in really light air, when you are motorsailing, the apparent wind swings forward A LOT. Main, blade jib, and a close winded code zero might be a good starting point to consider. The closer you can sail to the wind, the more you can use your sails motorsailing (and sailing, for that matter), so sail design is important, as well as reducing windage onboard as much as possible- it’s amazing what little things can do, especially since catamarans have fair amount of windage to start with. Which is why, if you’re going to use a wind generator, I’d suggest you don’t permanently mount it up- it’s an amazing amount of air drag- if you can swing it down when not in use, it’ll help a lot. It’s also amazing how little wind is force multiplied by electric power. Conversely, a tiny amount of wind coupled with e motoring can extend your e range exponentially.

What we’ve learned so far is that epower on a sailboat is basically sailing all the time, except more so- current and wind become much more important, as well as pure sailing skill. There’s a purity to it that is surprising- much closer to paddling.

I’ll look forward to future reports! Doing this on a cat makes a lot of sense.

When under sail is it possible to get a bit of regen to recharge the batteries?

It depends on your system- the Torqeedo saildrive + 48-5000 batteries, for example, with the fixed turbine prop (not the folding prop), if you’re sailing between ~ 4-12 knots through the water under sail alone, the fixed turbine prop turns (freewheels?) as the boat goes through the water, and charges the battery. That drag slows the boat down at least 2-3 knots, depending on the boat. It does argue for an outboard instead of an inboard, so you can pull the turbine out of the water when you don’t need/want the charging or drag. We went for the inboard and the folding prop more for aesthetics, handling, sailing ability, speed, and keeping the prop in the water when things get lumpy. IIUC, off the wind is better for regen. Given what even a bit of kelp around the foils can do to upwind ability, that sounds right to me. Depends on the boat- with a heavy boat, displacement/length of >250, who knows? We have an ultralight d/l -96- doesn’t take much to get her going, but it doesn’t take much to slow her down. In a couple of knots true wind reaching, with the code zero and main, plus what would be electric alone around 2 knots, we can do 6+ knots through the water, with very little battery draw. A few times, going across a tidal flow in no true wind, the induced tidal wind plus 2 knots electric got us 4-5 knots. Apparent wind is kind of cool, little wonder Einstein was a sailor…

Anchored in a tidal race with the fixed turbine set to freewheel /regen might do the same as regen under sail? Add deployable solar / wind turbines- energy all around!?

Torqeedo info is on their site.

Thanx!