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Electric liveaboard catamaran project

Posted: Oct 27 2021 7:14am
by patrickza
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.

Re: Electric liveaboard catamaran project

Posted: Nov 01 2021 8:11pm
by Hillhater
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 ! .

Re: Electric liveaboard catamaran project

Posted: Jan 12 2022 6:49am
by patrickza
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.
EnginesOut.jpeg
EnginesOut.jpeg (297.5 KiB) Viewed 724 times
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.
SolarPlan.PNG
SolarPlan.PNG (1.65 MiB) Viewed 724 times
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.

Re: Electric liveaboard catamaran project

Posted: Jan 12 2022 12:06pm
by SlowCo
patrickza wrote:
Jan 12 2022 6:49am
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.
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: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

Re: Electric liveaboard catamaran project

Posted: Jan 12 2022 11:51pm
by Hillhater
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 !

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 12:07am
by SafeDiscDancing
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.

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 12:45am
by JackFlorey
SafeDiscDancing wrote:
Jan 13 2022 12:07am
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.
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.
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.

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 1:10am
by patrickza
SlowCo wrote:
Jan 12 2022 12:06pm
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: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
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 wrote:
Jan 13 2022 12:07am
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.
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 wrote:
Jan 12 2022 11:51pm
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'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.

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 6:34am
by SlowCo
patrickza wrote:
Jan 13 2022 1:10am
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.
Although a project on its own, I love the EV conversion of an outboard motor "goatman" is doing for his Bayliner:
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 ... outboards/

https://www.edyn-marine.com/product/101 ... m-battery/

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 10:14am
by SafeDiscDancing
patrickza wrote:
Jan 13 2022 1:10am
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.
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.

Re: Electric liveaboard catamaran project

Posted: Jan 13 2022 5:33pm
by Hillhater
patrickza wrote:
Jan 13 2022 1:10am
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.
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 )

Re: Electric liveaboard catamaran project

Posted: Jan 14 2022 3:16am
by patrickza
Hillhater wrote:
Jan 13 2022 5:33pm
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 )
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...