Solar Array Location

[Indefatiguable]

Hey all,

So like so many of us I've had my solar array mounted on the bimini frame. My boats a Formosa Ketch, and shade from the Mizzen (even the boom to a limited extent) is significant. Additionally, the glass of my panels has roughly 1/2" clearance below the mizzen boom itself which invites headaches and breakage aplenty. I'm bringing that array back home to run my wintering grounds and will be speccing new panels for the boat, so I have room in size/shape etc.

What I'm thinking of doing is lining up the panels (standard rigid frame panels btw) in a single row, putting some gal steel angle iron around the whole rectangle so it's nice and solid, and attaching a spare mizzen halyard to one end plus a spare main halyard to the other end, hoisting it up tight and running the final +/- lines down the mizzen mast (pretty good location, charge controller batteries etc are close by).

My main mast is only slightly taller than my mizzen, so there would be a slight aftward declination of the whole array (perhaps ~15 degrees) but on the plus side there's almost 0 possible shade. I run in full series so any shade is bad.

It would not be difficult to add appropriately sized "side stays" to stabilize the thing against rolling over, and I understand that I need to appropriately size the +/- wiring running down the mast to account for the length of the wire run.

It also would be possible to lower the array via the halyards for service/cleaning etc.

Total weight should be in the neighborhood of 250-300lbs including all mounting hardware, and that's a high estimate - 200 is possible but unlikely.

Just FYI I'll be running >1.6kw solar total (48v Elec motor replaced old volvo), that's why optimal shade-less-ness, and such weight, is needed.

Yes, all that weight would be aloft. Yes, that's one of the main worries I'm having when considering this whole thing.

So.. Please do feel free to poke holes in my idea and let me know the problems I haven't thought of. Additionally, if anyone has some input on the effect on seakindliness, motion, handling, etc of all that weight aloft I absolutely would like to know as I'm still pretty new to owning and skippering a boat this size.

For reference, total displacement is ~18000 lbs with around 35% ballast/disp ratio.

Thanks in advance

[BillKny]

I am guessing you have a Formosa 30, based on the weight and other minimal details you post.

Lets do some quick numbers... If you hang 250 pounds of solar panels roughly 30 feet above your center of buoyancy, that's a moment of 250*30 = 7500 ft-lbs working to tip you over.

Your keel weighs 4000 lbs and probably has a center of mass maybe about 3 feet below your center of buoyancy. That's a righting moment of 4000*3=12,000 lbs.

That's all really, really rough, and ignores a lot of variables, but it tells me that your idea is very roughly equivalent to throwing away 7500/12000*100%= 62.5% of your keel.

Does that sound like a remotely good idea to you???

And we aren't even talking about the problems of safely hanging all that up there where a failure will kill people on deck.

[Indefatiguable]

Hey,

Thanks for the quick reply and more comprehensive math than I've come up with so far. It's a 36, but i've been unable to find exacting numbers hence the approximations. Pretty sure ballast weight is 4500lbs but both the Admiral and my first mate disagree to a wide margin.

No, that sounds terrible as I thought it might. Thanks for the help bud.

FWIW, and just to be thorough, if i were able to somehow finagle total array weight down to - lets say 100lbs (flex panels v. rigid, lightweight framing of fiberglass or whatever vs angle iron etc etc).

I input those (4500 bal, 100 array) into the calculations you provided and it came up to ~22% (correct me if i'm wrong, please and thank you). That's still pretty far from acceptable.

My question now is are the other variables you provided, specifically center of bouyancy and keel center of mass fairly loose as to not need alteration? how rough are those numbers? Rough enough to allow potentially lowering that 22% enough or no?

I wish i wasn't 10 hours away from the dang thing otherwise I'd have more precise numbers.


As far as potential failure dropping weight on deck, I'm confidant enough in my fabrication skill and maint vigilance to mitigate that into acceptable margins.

Thank you, quite seriously, for your input bro.

[Indefatiguable]

Addendum,

that ~62.5% -> ~22% number would need to be probably 5% max to be worth further expenditure on development.

Thanks

[Indefatiguable]

Further Addendum,

I was able to pull up a line drawing of the boat and estimate the aforementioned variables to be fairly accurate, with maximum hopeful numbers dropping that 22% to only 17%. Not enough.

Thanks again bud, back to the drawing board it is. Perhaps a new charge controller properly specc'd to allow running panels in parallel to mitigate shade dmg + a slightly taller mizzen mast step to give a comfort margin in boom<->panel clearance.

[wholybee]

I have panels in 2 strings on the lifelines on each side of my boat. I think it is a lot better location than a Bimini because it they aren't directly under the shade. I can have more panels, and more of them are not shaded.

The weight is down low, and I can sail with them all deployed, only folding them down and securing them in severe weather.

[Indefatiguable]

holybee,

I've toyed with that idea. Weight wise that's even better than the cabin top, probably as ideal a location as could be done.

Am i correct in assuming that the operating principle of such a design is that you essentially have 2 complete arrays (one on each side) that are both (mostly) adequate to your needs so when one side is shaded the other is in full sun?