Na Mara,
Well, color me a little confused here (and I'm a darn smart guy).... LOL
And, there is a lot to unpack from your post / questions....so, please bear with me for a minute as I unpack / decode some things, that will allow me (and others here) to better help.
Seriously, I will get to your questions/answers in just a sec....but, just want to give you a bit of background info and ask you for a clarification up front.
1) I professionally designed/sold/installed my first solar array/off-grid system (on land) in 1984....and had been playing with solar/alt energy for a few years before that....and in the late 80's/early 90's stated working on solar installs on some boats....
I designed/installed my
current solar array on my
current boat, in 2006....and I still keep up with changes/improvements in solar technology, etc...
http://www.c470.jerodisys.com/470pix/47004.htm
I also installed (and still use) a water-generator to use when at sea on passages (usually only when cloudy/overcast)....and while it's certainly secondary to solar, it does
work and does serve a purpose, particularly on long passages...
http://www.c470.jerodisys.com/470pix/47074.htm
https://hamiltonferris.com/images/pdf/pdf_359.pdf
SO...
In addition to my professional background in communications/engineering, I have experience with both solar and water-generators on boats as well...so, I'd like to offer a bit more than checking your math.
{And, to be clear, the biggest issue I saw right up front with your math, was that you're assuming some things about energy generation (and consumption) that is not consistent / repeatable (which effects the math) and you're combing A/H's (what you're representing as Ah's) with A/H's per-day, etc., which also effects your math....see below for some details.}
2) A North Atlantic circuit / circle is something I've done multiple times, and understand well....sailing from US to
Europe....and back from
Europe to US/Caribbean....having done my first crossing decades ago (in the pre-GPS days, when we used a
sextant and DR), and my most recent crossings on my current
boat, just a few years back.
BUT...
But, I think we may be referring to two different things, as you mention sailing between
anchorages? Nowhere to "anchor" in the middle of the North Atlantic....so, I suspect that you're writing about coastal sailing? Or are there language issues confusing me?
So, could you please let us know where you are located, where you are planning on sailing, and just as important, when you will be sailing in these areas....('cuz sun angles, and hours of daylight, vary greatly in different areas during the year....as well as ambient temps / water temps, effecting refrigeration energy consumption.)
3) As you can see, I have both the professional/engineering experience and the
offshore sailing experience, with solar and water-generators....
So, I hope you will take my generic recommendations/advice seriously? (and then we can discuss / help with your specifics)
a) Install as much "unshaded" solar panels as you can afford, and as much as you can fit on-board....(also allow adequate ventilation under / around the
panels, as their output drops off when they get hot)
{Since you mentioned the "Watt & Sea" water-gen, I'm assuming you have a decent budget to work with? So, I highly recommend SunPower panels.....the SunPower X-22 panels, such as the X-22 360 watt panel is 41" x 61", and because of their cell design is not only very efficient but also produces more power at lower sun angles, which translates to more power per day....more A/H's per-day...so, go with Sunpower panels and one or two Morningstar MPPT controllers, and you'll be very happy....and you'll save many $$$$ versus buying/installing a watt & sea system or two!}
b) Make sure you reduce/eliminate any shading of the panels....(a small/minor shadow from a stay or
halyard is usually not a major problem, but shading is a big problem)
c) Use quality MPPT controller(s) (Blue Sky or Morningstar)
d) Improve insulation of your refrigerator (and freezer, if so equipped)...reducing energy consumption
e) Manage sail trim / helm balance, as best as you can (improve as much as you can) reducing autopilot energy consumption.
If you do those simple things, along with a decently sized
battery bank (larger than you have now), it's highly likely that you'll be 100% (or at least 90%) energy independent, meaning no
diesel needs to burn for you to sail for days (or weeks) and relax at
anchor for days/weeks as well....at least with good sun angles of summertime (or wintertime in lower latitudes)
4) Those are the generic recommendations, that apply to 99% of sailors out here... and now, here are some specifics (but these depend on where / when you're sailing?)....
a) You don't need to build an "arch", nor do you need
davits to mount panels on (although, if you are thinking of
davits, they do make a good place to mount solar panels)....but, you can use the space you have more effectively....first off, remove / move the TV
antenna that is on your
radar pole....you will find it will work just as well if you move it a foot below the
radar scanner, or even on the stern rail...
Then move the
GPS antenna / receiver
outboard, place the
GPS antenna on the TV antennas old mounting....
This gives you a nice open/clean space to work with, in order to better design a solar array....with your radar scanner being the one thing to design around to keep the panels from being adversely shaded (usually by placing the panels/array at this same height of the radar scanner).
b) Your pictures do not show much of your boat, and you've not said what boat, so it's difficult to say....but, it appears that you do have room above the
helm area, aft of the boom, for a decent sized solar array?
Even if some of the array extends forward, so some of it is under the boom, as long as you move the boom
outboard a bit (not close-hauled), you would avoid boom-shading?
Although, you would have some minor shadow from your
backstays, if you use two panels here (one on each side) in parallel, or two panels each with their own controller (the best approach) these would have little effect on array output...
{note that if you used only one panel there, and then had two shadows on it, the output would probably be measurably effected.....please understand that this is something that many/most "professionals" in the alternative energy business know little, to nothing, about....and neither do most sailors....and here again, is another reason why it is VERY difficult to make specific recommendations for a boat we know nothing about...
}
c) If you don't mind a small aesthetic effect, it appears you could place a decent sized array, aft of your helm / above the transom area?
Using your radar pole as the starboard-side support (with some added
hardware / brackets), and then adding another "pole"/support on the port-side? Keeping the panels up high, so that the radar scanner itself would only shadow the panel(s) when sun angles are very low?
Or...or depending on the space you have (I have NO idea, as I don't know your boat), you could have panels here (aft of the helm / aft of the backstays) AND other panels above the helm area (forward of the backstays), as I described above in "b"...
d) Take note that rigid panels (of reputable manufacture, usually not made-in-China) will not only be more efficient than flexible panels, but they also last a LOT longer! (some with flexible or semi-flexible panels find they get 5 years out of the, but many find they only 2 to 3 years, before serious power degradation or total failure....those with good-quality rigid panels typically get decades of life....and Sunpower panels have 25 year warranties where they guarantee spec'd output at specific ages....fyi,
Kyocera does this too....but it's darn hard to find
Kyocera panels these days....)
So...
So, while many folks these days have jumped on the "flexible panel" bandwagon, usually this is a diminishing return....and many regret it....fyi, those
race boats you see plastered with flexible panels have repair/services crews in various
ports to repair/replace things, we cruising sailors don't!
And, we just want something that works, works 24/7/365, for years! And, that means high-quality rigid panels (Sunpower, Kyocera, Sanyo, Shell / Seimens, etc.)...
So, again not knowing your boat nor the dimensions you have to work with....nor the constraints you have regarding aesthetics...nor even the most important variable, your
budget for all of this....it makes it very difficult to make specific suggestions....except for the above recommendations, and the strong
advice here to use rigid panels...
e) Now, for someone (me) that has successfully used a water-generator on passages, you may be wondering why I haven't mentioned this as a priority?
The answer is four-fold:
--- Solar is much better overall....a decent-sized solar array (and good quality MPPT controller) will produce more power in a day than you will typically get from a water-gen (unless you sail at 10+ kts, and its always cloudy where you sail)
--- A water-generator only works when moving (and no matter what watt&sea says you will only see significant power at speeds of 4 kts and higher....and please figure about 60% to 70% of their factory output specs, as your actual real output...so figure about 6amps at 5 kts, and 7 - 8 amps at 6 to 7 kts...so, let's just be generous and say you'd get 6 to 8 amps for 24 hours, that's ~ 150 to 190 A/H's per-day....you'd get that much from a decently-installed solar array of ~ 360 to 450 watts...please read my article I wrote a while back, referenced above...)
--- Solar is maintenance-free....all you need to do is splash some water on them from time to time, and wipe off any bird-poop....and they will last you a couple decades or more, with no issues at all!
--- Solar is silent.....now, you think a water-generator would be quiet, too....but, it's not... Depending on how it's mounted/installed, you can find it a bit noisy (mostly vibration)....understand that the "towed-water-generators" (like I have) have much less vibration issues, as the prop is 75' aft of the boat, and the line connecting it to the transom-mounted motor/generator absorbs most of the surges/vibrations....
Now, I'm not saying a water-generator is bad....but they should always be secondary to solar....and the Watt & Sea is notoriously a
maintenance issue....ask around, and you'll find many that have found the mounting / hinge system to be prone to early failure (within months) as well as other issues....
(as well as it being wicked expensive....the "300" model is 2908 Euros / ~ $3500 USD, and the "600" model is 4990 Euros / ~$ 5900 USD....my Hamilton Ferris 200 (which is spec'd about the same as the watt&sea 300) cost me just over $1000 USD, plus a couple hundred dollars for spare line /
parts (which are still brand-new, never used)
There is more to say, more to explain, more to do....but, nothing more I can do now, as I don't know much about you, your boat, your cruising area / cruising plans, your budget, your aesthetic constraints, etc. etc....
So, I think this will do for now...
I do hope this preliminary info helps.
Fair winds.
John
P.S. Bottom line here: Read all above again....and follow the recommendations in #3 (3a, 3b, 3c, 3d, and 3e), and you will save a lot of $$$ (or Euros), have a quiet/silent time on-board, with no extra maintenance, and not burn fossil fuels to generate electricity!