Liveaboard solar electric boat

[CaptainJohn49]

Originally Posted by Nauti Cat

I’m looking for advice and suggestions on getting a solar/electric catamaran.
I would like to find a boat without engines to put a Torqueedo hybrid system in with solar panels for living on the hook.

And if anyone has experience living on the hook with solar-How much energy needs to be produced per day. I would be in south Florida and Caribbean so would need a/c 24/7 most of the year plus the usual appliances and tv.

Ideal boat would be 40-46’ at 25,000-30,000#, with a beam of 20-28’. Also I’d prefer to use the outboard version of their electric 55kw motors.

Why don't you get a Westsail 32 for about 30k, go sailing wherever you want, stop, go to a local bar, have a cold beer or three, watch some TV, cool down in the AC and enjoy life. You'ii be $300k richer, meet lots of locals, enjoy new foods, go places you never dreamed of and have fun.


Sounds like you want to stay inside, watch TV, have everything in the frig., and keep cool. No need to exit the comfort zone. Having a movable apartment won't make you a happy person.


CaptainJohn49

[peter57]

Originally Posted by StuM

I think he is talking about 20-30,000 pounds displacement, not cost.

Is that not heavy for a cat as my old 1961 SS 43'LOA 13' beam 7'1" draft was 10 ton dry. Half of that was lead, apparently.

[StuM]

Originally Posted by peter57

Is that not heavy for a cat as my old 1961 SS 43'LOA 13' beam 7'1" draft was 10 ton dry. Half of that was lead, apparently.

I suspect that he is talking about a powercat (no way to get the solar he's after on a sailing cat of that size).

The Silent 44 is apparently 11 ton (22,000#) lightship and he's looking at finding an existing catamaran hull which doesn't currently have any propulsion and creating something similar from scratch.
Don't know how much he would save compared to just buyng a Silent for a milliion bucks or so.

[john61ct]

Pretty sure OP did not start out here with much clarity or background information before posting that wishlist.

And budget not being mentioned, means unlikely to be unlimited.

But knowledge is being gained on multiple fronts, and that's always A Good Thing.

[Q Xopa]

Originally Posted by StuM

Hmmm!


https://hvacdirect.com/carrier-9-000...praq09aa3.html


Electrical 208/230 V. 1 Phase 60 Hz
Amperage Requirement 15 Amps


By my reckoning, that's over 3 kW or around 250 A @ 12 V.


Not saying it draws that all the time, but it makes that 460W maximum startup surge dubious to say the least.

So your reckoning is 12V at 250A ie 3,000W to run that air cond.

As you say, hmmm.

[Q Xopa]

Originally Posted by john61ct

2500W of panels as a minimum starting point for a small volume well-sealed and insulated space in mild weather, maybe 6-10 hours a day

will of course wildly vary not just by those factors, but also by thermostat setting and aircon efficiency

50Ah usable storage for each hour aircon used when panels not feeding most of the aircon directly.

Both over and above what the boat would require with aircon fed from shore power / ICE sources only.

And all this assuming ideal insolation conditions low latitudes.

ICE will need to make up the difference otherwise or proportionally add panels for off-season, higher latitudes, bad weather etc.

Those designing for this practically will likely be using ICE pretty regularly, to the extent they've foolishly allowed their bodies to get acclimated / dependent on aircon.

Remember, the OP's use case was solar **only**, and **propulsion** as well!!

Is **anyone** knowledgeable claiming that enabling this scenario would be a practical project, retrofitting an existing boat suitable for liveaboard cruising?

'2500W of panels as a minimum'.

Ok good, any clues/ examples/ references/ calulations etc how you arrived at that number?

Anyone can throw WAG numbers around.

[valhalla360]

Originally Posted by StuM

Hmmm!


https://hvacdirect.com/carrier-9-000...praq09aa3.html


Electrical 208/230 V. 1 Phase 60 Hz
Amperage Requirement 15 Amps


By my reckoning, that's over 3 kW or around 250 A @ 12 V.


Not saying it draws that all the time, but it makes that 460W maximum startup surge dubious to say the least.

And this is for a small 9k btu unit.

We had 12k btu on our small cat and it struggled just to keep the salon cooled with the rest of the boat closed off once it got hot.

[CatNewBee]

Originally Posted by Nauti Cat

I’m looking for advice and suggestions on getting a solar/electric catamaran.
I would like to find a boat without engines to put a Torqueedo hybrid system in with solar panels for living on the hook.

And if anyone has experience living on the hook with solar-How much energy needs to be produced per day. I would be in south Florida and Caribbean so would need a/c 24/7 most of the year plus the usual appliances and tv.

Ideal boat would be 40-46’ at 25,000-30,000#, with a beam of 20-28’. Also I’d prefer to use the outboard version of their electric 55kw motors.

https://www.energymatters.com.au/ren...amaran-em5211/

https://www.energymatters.com.au/wp-...-catamaran.jpg

https://catamaranguru.com/catamarans...olar-catamaran
https://catamaranguru.com/images/art...-catamaran.jpg

Maybe 4u? Only you need to append some 0's to your budged.

[valhalla360]

Originally Posted by CatNewBee

https://www.energymatters.com.au/ren...amaran-em5211/

Maybe 4u? Only you need to append some 0's to your budged.

Doesn't give price but the soelcat 12m gives a good starting point of what can...and cannot...be done.

This boat has a roof over the entire deck space of the boat...total solar panels 8.6kw.

120kwh of batteries at 8kg per kwh...literally a ton of batteries.

8kt for 6hr off 120kwh...works out to 20kw to make 8kt...That's bout 30hp (actual output from the motors) to make 8kt on a light skinny hulled catamaran...that seems reasonable.

Assuming 4hr at the rated wattage, that's about 35kwh per day of generation. Assuming 5kwh is lost due to efficiency, that's about 4 days to charge a dead battery bank, if you use no power.

There are a few caviots that are unclear...is that 8kt speed running empty in calm conditions or does it include typical loading. A cruising boat will almost never run empty and long skinny cat hulls lose a lot of speed and efficiency when you overload them.

Assuming 5kwh lost to efficency and another 5kwh to other house loads, 25kwh usable at 1.5kw for the air-conditioner (not buying the 500w numbers as real world numbers are typically in the 10-15amp @120v range), means you can accommodate an 69% duty cycle (16.5hr out of 24). If you stick to temperate climates where, you will see the duty cycle drop off at night, you are borderline making it work and the battery pack should be sufficient.

If this boat sold at the same price as a standard 12m cruising cat and didn't lose performance, I think it would be a winner. That's reasonable range for coastal cruising (6*8=48miles in a day). If you stay in marinas, you could charge overnight (you will be pulling max amps from a 50amp connection all night). If you wanted to charge overnight at anchor, you would likely need something on the order of a 12kw generator (10hr * 12kw=120kwh) but that could get annoying having the generator running flat out while you sleep.

But something tells me, you are going to see a price tag at least double what a standard cruising cat of similar size will run.

[StuM]

Originally Posted by Q Xopa

So your reckoning is 12V at 250A ie 3,000W to run that air cond.

As you say, hmmm.

No, I'm saying that that's what the manufacturer says is the wattage (presumably peak) required for that equipment.

[valhalla360]

Originally Posted by StuM

No, I'm saying that that's what the manufacturer says is the wattage (presumably peak) required for that equipment.

I suspect that's the amp rating for the breaker and they often round up...but they don't round up by a factor of 6.

Even at 5amps actual draw, that's still more than double the 500w suggested.

[StuM]

Originally Posted by valhalla360

And this is for a small 9k btu unit.

We had 12k btu on our small cat and it struggled just to keep the salon cooled with the rest of the boat closed off once it got hot.

16K BTU/h here struggles in the afternoon to keep the saloon () cooled.
(With 800 W solar, we stil only ever run it on shore power).

[CatNewBee]

Originally Posted by StuM

No, I'm saying that that's what the manufacturer says is the wattage (presumably peak) required for that equipment.

That is pretty much what A/C use to draw. If I run all 4 units on board (42000btu) I need about 18...22A on 220V or up to 5kW. Too much for an inverter and even a 16A shore power connection is not enough. You can run maximum 3 A/C units on the 16A shore power outlets in the Med.

[Q Xopa]

Originally Posted by StuM

No, I'm saying that that's what the manufacturer says is the wattage (presumably peak) required for that equipment.

I think the numbers you are quoting are what the manufacturer wants the circuit capacity. There is obviously a good amount of saftey margin.

Ive seen people run their older bigger 16,000 BTU, cheap, ie alegedly less efficient air conds from 2000W suit case generators. Of couse some do, and some wont start depending on the specific generator and air cond units.

I dont know the actual numbers but Im pretty sure these units dont need 3,000W to start, or operate.

But Im open to better information.

[john61ct]

Yes regular Webasto 16,000 BTU units are fine powered by a portable 2000VA genset, just need to add an EasyStart.

8,000 BTU even runs in Eco mode.