Liveaboard solar electric boat

[a64pilot]

All this can I cruise an electric boat or run air conditioning we keep getting on here is sort of silly.
Of course you can, it’s simply a matter of scale, all the variables are known. Simply do the math yourself.
People have completely unrealistic beliefs in how much energy you can get from a panel, but that data is well know and been published, people are just too lazy to look it up and do the math themselves.

It’s like these building off the grid TV shows we sometime watch, at the end of the show they always show one or two smaller like maybe 100W panels and say this will provide all our electrical power needs.
But don’t tell you that those needs are four LED lights, they give you the impression that they are going to run a fridge, watch TV etc.

[Nauti Cat]

I looked seriously at an arrowcat 420 , but it's narrow beam doesn't quite have the liveability . What is nice about it is that it is set up for outboards. Has a nice long roof for solar panels and seems it would take very little power to move this light cat with low draft. Also it's hull was designed as planing hull with large outboards and I'd be better served by a displacement hull. But does it really matter that the hull was designed to plane at the speeds we are looking at (6kts)?

[CharlieJ]

Post#68 Valhalla360: June. St. Petersburg, FL. Hot and humid 90F/90%. Oh course it took about 6 hours to cool the interior and furnishings and that took a lot more power. But once cooled, 650W maintained it.

[Nauti Cat]

Originally Posted by a64pilot

All this can I cruise an electric boat or run air conditioning we keep getting on here is sort of silly.
Of course you can, it’s simply a matter of scale, all the variables are known. Simply do the math yourself.
People have completely unrealistic beliefs in how much energy you can get from a panel, but that data is well know and been published, people are just too lazy to look it up and do the math themselves.

It’s like these building off the grid TV shows we sometime watch, at the end of the show they always show one or two smaller like maybe 100W panels and say this will provide all our electrical power needs.
But don’t tell you that those needs are four LED lights, they give you the impression that they are going to run a fridge, watch TV etc.

I'm not sure what's silly about research, there is a lot of misleading information as you pointed out, so it takes awhile to filter through it, but I think the aircon answer is it could take 2kw to cool a 44 foot cat , but once cooled-less than 1kw will maintain.

[OldMan]

Originally Posted by Nauti Cat

I'm not sure what's silly about research, there is a lot of misleading information as you pointed out, so it takes awhile to filter through it, but I think the aircon answer is it could take 2kw to cool a 44 foot cat , but once cooled-less than 1kw will maintain.

That does not match my experience.


First, in the middle of the day with the sun shining bright in my 40+' catamaran, my (2) 16Kbtu AC struggle to lower the temperature, they do a good job on humidity. They will run, ~3KW total, full time in bright sunshine. When the sun goes down, they will catch up and cycle. Remember, boats are not insulated.


YMMV

[flyingfin]

Live for free,,,,,,great idea, wonder why no one has thought of that yet??

"We'll all be drinkin' that free bubble-ubb
And eatin' that rainbow stew
When they find out how to burn water
And the gasoline car is gone
When an airplane flies without any fuel"
Merle H.

[Simi 60]

We have 9 x 250w panels with no shading from sails
Have 800ah @ 24v of batts
A victron 5000 Va inverter/120amp charger

With that we run a couple of 240v fridges, ftreezer and a 240v HWS (that is charged while putting in max amps) plus lights, TV, pumps on occasion etc.

With all that there is no way we could run an a/c without raping the battery's horribly or running the 7.5 kva genset

[StuM]

Originally Posted by valhalla360

Looking at his channel, he seems to be promoting (ie: advertising/kickbacks) from the systems he's installing...so take it with a big grain of salt. Not saying he's lying but he is not an unbiased source of information.

I watched the first few minutes but my BS meter went off when he either completely misunderstood or deliberately misrepresented what SEER is.


As others have pointed out, a well insulated RV in temperate climates with an engine driven alternator every time they move is hardly comparable to the OPs situation.

[KP44]

Originally Posted by CharlieJ

I have personal experience with their 60,000 BTU/240VAC unit and have seen it keep a 44' power cat at 77F using 650W.

650 watts on a 240 volt system is just over 3 amps. (Including the normal loss for alternating current.)

I just researched a 60,000 BTU AC unit. It requires 3 phase 460 volt power and draws 9.5 amps. (And "sale price" is just over 10,000$US.)

In other words, a 60,000 BTU AC uses about 4,400 watts and not 650 watts as you say above.

[a64pilot]

Originally Posted by Nauti Cat

I'm not sure what's silly about research, there is a lot of misleading information as you pointed out, so it takes awhile to filter through it, but I think the aircon answer is it could take 2kw to cool a 44 foot cat , but once cooled-less than 1kw will maintain.

What is your reference for that?
How much it takes to maintain temp depends on heat load, and that greatly depends on insulation and solar gain, Solar gain in particular is huge. Next July and August take an IR thermometer and shoot your cabin roof with it, on the inside of the boat. You’ll likely be surprised what you find.

In the middle of Summer in my 38’ mono it takes 22,000 BTU to maintain a nice high 70’s temp. During the day, and that isn’t cooling it down, that’s maintaining a temp.
Now you can take that 22,000 BTU number and determine how many watts it takes to get there with an efficient system, I can tell you with a Marine System, by they aren’t particularly efficient so they are kind of out of there for Solar usage. I assume for that your going to need a house type of split system, an efficient one.

Now an assumption is that any kind of Solar boat will live in the shade, none of the boat will ever get direct sun because to work it’s going to have to have as much Solar as is possible, it will look like a flat table with a boat under it.
Being shaded will help the heat gain tremendously, as will insulation.
Maybe a couple of feet at least between the boat and the panels. That will help with heat gain, and allow cooling air flow under the panels which helps with output, plus you need to get to the underside if there is every any kind of wiring issue.

If I were to try this, I’d first assume this will never be a “blue water” boat, but always stay in protected waters, so I’d go find me the biggest pontoon tubes there are, or even have some made, and I’d build myself an exceptionally well insulated little house to sit on the flat deck of a big pontoon boat.
I’d also put an outboard on one side and an electric drive on the other, just in case, leave the outboard tilted up and out of the water if you don’t need it.

Then I’d install a huge Solar array above it, as big as I could possibly get. Then spend as much money as a nice boat likely costs on an LFP bank and it’s charge system, inverters etc.

You could probably knock around the Keys with it in comfort, just have a hurricane plan.

[john61ct]

Exactly.

The boats that will be able to fulfill the OP's expectations, even if "mostly solar" rather than "solar only"will be **purposefully designed to do so**.

And other qualities valued by the market will need to be compromised in order to do so.

[CharlieJ]

Post 84:

In other words, a 60,000 BTU AC uses about 4,400 watts and not 650 watts as you say above.

I am so sorry to disappoint you but...this is me actually being involved with the installation, bringing it on line and then observing the unit cool the boat on a late May day with 90F/90% ambient. And me observing 650 W at 240 V on the dedicated control panel. Not you reading some specs. Go research the Termodinamica unit that I referenced in the first post.

[valhalla360]

Originally Posted by CharlieJ

Post 84:

I am so sorry to disappoint you but...this is me actually being involved with the installation, bringing it on line and then observing the unit cool the boat on a late May day with 90F/90% ambient. And me observing 650 W at 240 V on the dedicated control panel. Not you reading some specs. Go research the Termodinamica unit that I referenced in the first post.

And as a certain radio personality used to say...."and now for the rest of the story...."

Not buying it unless you've purposely left out a lot of key info.

[Q Xopa]

Originally Posted by OldMan

That does not match my experience.


First, in the middle of the day with the sun shining bright in my 40+' catamaran, my (2) 16Kbtu AC struggle to lower the temperature, they do a good job on humidity. They will run, ~3KW total, full time in bright sunshine. When the sun goes down, they will catch up and cycle. Remember, boats are not insulated.


YMMV

I dont have air cond.

I agree most boats are not Insulated. However I have insulated mine. I know others that have also done it.

It was some effort, but made a good difference with mine. I couldnt fit as much as I would have liked as my ceiling liner hasnt got much space between to the deak.

[Nauti Cat]

Originally Posted by Nauti Cat

That's just about exactly what I'm looking for, would those 9Kwp panels run aircon and appliances on a typical live aboard day and leave batteries full without running generator so I could also do a day cruise of about 50 nm on batteries (again without running genset)

And the silent 44 with options runs $1.4m

someone asked about budget= $1m
The silent 44 looks to be ideal, but over budget. also the Aquilla 44 converted to solar/electric. Best option I see at moment might be the arrow cat 420 with solar and 2x Torqeedo 55kw outboard-might be able to convert this boat for under $1m , but it's a little narrow for what I would like.

and yes, to answer another poster. I am kind of looking for a "movable apartment", don't need to go fast , just change locations by up to 50nm once in awhile.

Any other existing boat or possible conversion suggestions?