Help mounting solar panel on davits

[NotCook]

I have a new 123W solar panel and I am going to mount it on my stern davits. There is room between them and they extend far enough to allow the panel to remain within the confines of the davits and aft of the mizzen traveler. I am looking for ideas on how to go about mounting the panel on the davits. I will need to attach some kind of framework on the davits to which I can attach the panel. I like to solve challenges like this myself, but I would appreciate input on this one. Any thoughts?

The davits are steel, and painted, and they are 2" by 3" enclosed beams. I have attached a photo, which is not the best angle, but it is what I have available. From this angle it doesn't look like the area is clear, but it is.

I am assuming I will need to attach two rails across the davits, to which I attach the panel. Any thoughts on the material, and source thereof?

Thanks for any ideas!

Brian

 

[sailingdog]

I don't see any attached photo. And a photo would be really useful for this. Chances are pretty good that you can weld tabs or bolt brackets to the davits that you could bolt the panel to. This would probably be about the simplest way to do it.

 

[Johnb]

Be aware that shadows cast on solar panels affect them out of all proportion to the size of the shadow. This is because the shadowed cells become high resistance, reduce output and can even be damaged by the current from the other cells.

John Brecher

 

[Ross]

I think that I would try a good lashing to attach any framework to see if that position will serve you well. Later you could resort to a more permanent installation.

 

[Ron20324]

Not knowing how strong the frame is on the solar panel, keep in mind if you bolt it right to the davits, the davits may twist and therefore twist the panel and damage it. Partucularly with the weight of the dingy. I'd put some lumber across the davits then attach the panel to that.

 

[sailingdog]

Given the photo, the davits appear to be pretty widely spaced, and you may need a cross beam added to support the solar panel.

John is right about how shading can seriously compromise a solar panel's output, although I've never heard of one so badly designed that the panel could damage itself.

 

[NotCook]

Not knowing how strong the frame is on the solar panel, keep in mind if you bolt it right to the davits, the davits may twist and therefore twist the panel and damage it. Particularly with the weight of the dingy. I'd put some lumber across the davits then attach the panel to that.

Ron, absolutely right. I wouldn't want to just depend on the structural integrity of the panel itself. I like the idea of lashing some thing across before a permanent solution, and I like Dog's idea of welding attachment points for whatever framework I ultimately decide on.

I think I would like to find some kind of 1' square steel tubes to build that framework, but right now I don't have any idea where I would go about finding that.

Just some additional information: The davits, at their aftmost and narrowest point are 66" apart, and the panel is 59" wide. I think I would just need 2 support beams running between the davits, and possibly some crossmembers between those.

 

[Ross]

Baltimore has several steel suppliers and Lorain must have more than a few. The scrap yards are also a good source for metals of all sorts.

 

[Ed Schenck]

It appears that your mizzen backstays attach to the ends of the davits. Is that the case? If so then they must be extremely well built. I would weld one cross brace as far aft as possible. Then I would hinge the panel to that. I would still use a cross piece on the forward edge of the panel. But I would design it so that I could tilt the leading edge upward. I know how to do that just not how to explain it.

One inch square tubing is overkill I think(I buy my steel at Slesnick's in Canton, OH). I think 3/4" angle would more than suffice.

 

[Ross]

They sell one inch square aluminum tubing in most hardware stores. Supporting the panel in a strong frame and pivoting it at its center line would allow you to adjust the angle reletive to the sun. The ideal would be to mount it in a gimbal.

 

[Ron20324]

Brian, I can't tell if you're here in Annapolis now? There's a steel shop where I get mine from. (There and the dumpster at the air conditioning shop.) It off Chinquapin Round rd, the same street as Echoes and Accents.

 

[sailingdog]

Considering the davits are made from 2" x 3" steel box extrusions, I'm doubting that they're going to be twisting or warping anytime soon. Also, in the photo, it appears that the mainsheet traveler is mounted on a crossbeam on the davits, which gives some indication of the strength of the davits assembly.

 

[Bob V]

Stainless grab rails

are commonly attached to the sides of dodgers and can be made to any length. A bolt is welded into the end and then you just need to drill the square tube steel in the appropriate places. When used on canvas leather washers are used to protect the canvas. Use 1 1/4" tubing for greater strength.

As others have pointed out, there is a lot of shade on your davits from all the lines. A skinny shadow that extends all the way across the panel will reduce the output way beyond what you would expect.

 

[Ron20324]

Considering the davits are made from 2" x 3" steel box extrusions, I'm doubting that they're going to be twisting or warping anytime soon. Also, in the photo, it appears that the mainsheet traveler is mounted on a crossbeam on the davits, which gives some indication of the strength of the davits assembly.

That being the mizzen traveler. Each davit being strong in it's own right, the two still may go thier separate ways and split the panel like a wishbone. What looks like the mizzen backstays would add the mast to the torsional twist. Still, a frame to support the panel is needed. I like Bob's bimini mount!

 

[sailingdog]

Ron—

The cross piece the mizzen traveler is mounted on would appear to prevent the two from moving in relation to each other, as it is attached to both by the looks of it.

 

[John Nantz]

You know what they say about ONE panel... ?

.... it's a good start.

(You said that you got "A" panel..)

It's been mentioned above about shade and shadows, and by looking at all the lines, mizzen sail cover on the boom, mizzen mast, etc., what you're going to really need are TWO panels to keep one of them in the sun (hopefully). So....

What about putting one panel on the outside of each davit so it can be adjusted to either hang down or pivot up to the horizontal?

Solar panels have aluminum frames so a word of caution about about steel, and stainless steel, attachments. Steel should be isolated from aluminum or there will be galvanic corrosion problems.

Also, I like the idea of clamps or welding on the davits as opposed to any drilling of holes (just in case you might think about doing this) which can weaken the structure.

 

[JerryA]

Beautiful boat Brian! I think I sailed by you in Sandusky Bay last summer while you were anchored. If your boat is up here in Lorain, I'd give you a hand putting something together.

JerryA

 

[NotCook]

.... it's a good start.
...I like the idea of clamps or welding on the davits as opposed to any drilling of holes (just in case you might think about doing this) which can weaken the structure.

That is my feeling as well. I am on the bolting or welding page, just a Dog pointed out in his initial post. Also, I've been considering the galvanic issue, but I expect the only way to avoid it would be by isolating the connecting bolts with grommets. Something is going to attach to both steel and aluminum.

I will have to consider the idea of panels hanging on each side of the davits. I like the concept, but I have to say the thought of 50+ kt winds blowing from either beam while docked in Ohio (where we are currently, Ron) gives me a little heartburn. Not sure a vertically mounted panel would survive a storm. Now, once we are in the Carib, and only at anchor, so that we always swing into the wind, I think that will be an excellent option for those additional panels. However positioned, the attachment will have to be substantial...

I am leaning towards Ron's initial idea, and doing a preliminary test using some bimini type tubing attached by square u-bolts. I can use bimini parts to attach the panel to the tubes. That will also give me some hinging options.

It is going to be interesting to see how the back stays are going to impact the output. Those and the wind generator tower (attached on the port davit) should be the main source of shadows. Naturally, the mizzen boom will be a factor when the sun is forward, but, it IS a sailboat!

This is a great forum!