Liveaboard solar electric boat

[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.

[john61ct]

The topic of electric propulsion is fraught, been recycled dozens of times

https://www.google.com/search?q=site...+OR+propulsion

Same concepts as "solar powered aircon" really.

And both edge case / speculative topics, should really be segregated from the very much less controversial one, of solar recharging for House bank usage.

[smac999]

There is no way you are going to run a/c and an engine from solar. Unless you rarely move. And rarely use A/c

[tkeithlu]

Agreeing with Smac999, and

Look, you have a wild idea. Lots of other people have had the same idea, and members of the forum may be a bit tired of shooting down dreams that do not equate power in with power out. It keeps coming up, sort of like perpetual motion machine patent applications.

So, don't give up on your interest in solar, because it has improved in efficiency and price big time over the last few years. Start with the square feet in panels you can reasonably mount on your dream boat while still operating it, then figure in efficiency given hours of sun, angle to sun, etc., and then see how many amp hours you can get into a house bank, and how big a house bank you'll need. Efficiency again coming out, and what can you realistically do with it? Then think about how big a genset you need, diesel hopefully, running at half load for eight hours a day to make up the difference. Then start dreaming again.

There are a bunch of electrical system wizards on the forum. They write very long responses. I am not one of them. When you come back with a realistic design, I think they will gladly coach you through the finer points. Go for it, and have a good time at it.

[Nauti Cat]

I'm not debating the viability, I believe for what I'm looking for it is viable which would be living on hook for days or weeks in one spot then moving on 20-40 miles for awhile longer on a retirement schedule. While running would not need to run a/c (only while anchored)

Thanks for the link John, lots of good info in previous debates, but since I believe the system is viable with the right boat, I'm looking for suggestions on the right boat for Torqeedo system and any suggestions for setup or equipment to make life on the hook with this type of setup most comfortable

[StuM]

Aircon a 40-46ft catamaran for days at a time off solar/batteries in Florida/Caribbean?


Dream on. Just do the maths.

[Nauti Cat]

The silent-yachts 55 and Aquilla 44 converted to solar/electric don't seem to have a problem doing it. Also another boat on youtube called "top secret"
They all run aircon all day and night from solar/batteries

[StuM]

Originally Posted by Nauti Cat

The silent-yachts 55 and Aquilla 44 converted to solar/electric don't seem to have a problem doing it. Also another boat on youtube called "top secret"
They all run aircon all day and night from solar/batteries

Can you provide any reference to that 24/7 aircon from solar/batteries? especially in S Florida/Caribbean in summer?



Silent 44:
Fuel: 250 – 500 L
Solar Panels: 9 kWp
E-Motors: 2 x 30 kW / 2 x 80 kW
Generator: 22 kW / 100 kW
Battery Capacity: 120 kWh


Silent 55
Fuel: 500 – 1.600 L
Solar Panels: 10 kWp
E-Motors: 2 x 30 kW / 2 x 250 kW
Generator: 22 kW / 100 kW
Battery Capacity: 120 kWh


Why the large generators and fuel capacities?


Like I said, do the maths.

[john61ct]

Yes, bulldust, ICE sources required for anything more than a few hours of aircon a day, even that is a stretch.

And anything more than say a half hour anywhere near hull speed.

And choosing between one or the other.

100% for sure.

[Nauti Cat]

I'm doing the math and unless they are putting out bad info , the aircon draws less than 2kw and on a sunny day the solar panels produce nearly 50kwh , so with other appliances and maybe a little less draw from aircon at night, it'll be close and that's with full aircon. you could shut off air to rooms not in use at different times and stay under the 50kwh, but if you did go over , you would drain battery some , but if it go low enough , then run genset for a couple hours and get full batteries again.

Genset and fuel are mostly for range and speed increases when necessary to go faster or further based on hybrid style running. Also while running , I would think you would turn aircon off and just have airflow.

At least this is my understanding and it makes sense to me, have I been told bad info there?

[john61ct]

12kW of panels maybe?

How many square feet is that?

5000Ah battery bank?

How much does that weigh?

[john61ct]

Hybrid mode will use **a lot** more mpg than direct propulsion

[smac999]

A cat here with 2 Torqueedos And a $40,000 48v. Mastervolt lithium Bank gets 30 mins At full power.

It does not have ac, Is stored plugged into a dock. And has a generator

[valhalla360]

Originally Posted by StuM

Aircon a 40-46ft catamaran for days at a time off solar/batteries in Florida/Caribbean?

Dream on. Just do the maths.

If he gets a cat without a sailing rig and covers pretty much the entire deck with solar panels then installs a large battery bank, it's technologically feasible.

Very expensive and impractical...but technologically feasible.

Say a 40x20 cat with the entire deck area covered with a solar roof (100%) That's 800sft at 14w/sft...so about 11.2kw of panels. Assuming 4 times the rated output as the typical KWH production around 45kwh per day.

Let's say an air/con at 15amps @ 120v...That's 1800w x 24hr...works out to around 43kwh per day for air/con...Assuming you got a smaller air/con or multiple small units and only cooled specific areas, it could be done while having enough extra to cover typical house loads.

Of course, assuming production drops off by say 3pm and doesn't really pick up until around 10am...you need a battery bank of say 37kwh. But really you probably want double that as a cloudy day may result in not having enough to get you through the next day...so let's say you buy a $15k tesla battery pack with 80kwh.

How much is a 11.2kw solar array suitable for marine conditions including support structure, charge controllers, etc... to feed that battery bank...

Of course, this is pretty much an ideal scenario. Reality, you probably won't be able to cover 100% with solar panels. There are efficiency losses converting power. Windage would be horrible if anchoring in a storm. This is all before touching the propulsion aspects.

There are a few demonstration boats doing just this...but they are incredibly expensive and impractical.

[john61ct]

No lithium chemistry but LFP should be used on a boat, despite the lower density.

Unless (maaayybe, not me though) the whole setup is professionally engineered with a proven TMS and liquid cooling of the cells (good luck).

Certainly not packs from scrapped EVs sans all the protections.