Large solar array support beams

[s/v Jedi]

The first beam exists, is curing right now.

It was a four hours straight job, we’re shot. But everything went perfectly.

[sailingharry]

In the business world, I firmly believed in the quip that "A clean desk is a sign of a sick mind." It probably applies to clean shops as well.

But that detail aside, that looks like some pretty good work.!

[s/v Jedi]

Originally Posted by sailingharry

In the business world, I firmly believed in the quip that "A clean desk is a sign of a sick mind." It probably applies to clean shops as well.

But that detail aside, that looks like some pretty good work.!

Ha! You realize I’m an amateur and this is just a couple garages where we also park cars and stuff

Yes, I think the beams will come out really well… which they should as it’s about $1k on materials alone!

[s/v Jedi]

Overall the beam came out great. We have to do some sanding on two surfaces where the peel ply formed wrinkles and resin accumulated underneath. This is the first time we use peel ply and I think it doesn’t handle a slightly shrinking in size of the beam as resin is squeezed out. The fibers just compress into a tighter weave but the peel ply is a plastic that can’t do this. As this lamination is wrapped all around, there’s nowhere to move for excess peel ply other than to wrinkle.

We could leave out the shrink wrap to prevent this but then there’s more resin in the laminate… but if it eliminates sanding I think I can live with that thought

You can clearly see how the two short sides have double the amount of carbon fiber and it’s shaped a bit like train rails. I will weigh it later

[s/v Jedi]

Some numbers: the height of the beam increased by 7mm so 3.5mm laminate thickness per side and this is the part that includes the layers of uni-directional fiber.

I can’t precisely measure the wall thickness of the side of the beam until I cut the beam to it’s final length.

I calculated we added 1.32kg of carbon fiber and 1.48kg of epoxy resin and the weight of the current beam is 12kg up from 9.2kg. I believe we are close to the 50/50 ratio of carbon and resin but added some resin to the outside surface with the peel ply but that should reduce the amount of fairing compound used before painting.

[BG305]

Originally Posted by s/v Jedi

Yes, I did notice Can you post a link to the sliders you found? Note that I need 44” or longer ones.

I do believe I will get many years of service out of these, because all the exterior surfaces will be coated either with paint or a tape (need to isolate different metals) and the interior bearings and bearing races I will regularly address with rinsing and Boeshield T9.

I have similar sliders in use inside the boat for the past 4 years and they look like new without any additional measures.

I looked at aluminum sliders but the shipping coasts alone were $700, then they were twice as thick and cost $350 each ($700 per pair).

Did these end up not being a good fit?

https://gsfslides.com/applications/m...non-corrosive/

[s/v Jedi]

Originally Posted by BG305

Did these end up not being a good fit?

https://gsfslides.com/applications/m...non-corrosive/

No… just shipping alone was $700 which added to the sliders came to around $2,000.- because the price they list isn’t for a pair but for each single one.

I now spent $300 and we’ll find out how many seasons they will last. I think I’llbe able to keep them going for a while.

[BG305]

Understood, that is a serious shipping fee. 🤔

[s/v Jedi]

So I just did the sanding of the first beam. You don’t really have to be careful to not touch the carbon fiber because it is harder than the sandpaper

The observed wrinkles are indeed just resin and I could easily fair it out using the mouse sander. Where the last layer ends, the peel ply had created a neat flat end and I simply sanded over it where you now see the carbon where the fabric ends and epoxy next to it as fairing compound.

I don’t think I will be using fairing compound. I’m even thinking about maybe finishing it with clear coat to show off the carbon fiber laminate. Not sure about UV protection though… does anyone have more info on that?

When I knock on the beam it sounds and feels like a thick wall steel beam, perfect! Still thinking on how to cut it to size… the miter saw must be the best option, right?

[Chotu]

I haven’t really ventured in here. Been underwater with my projects. I wish I had. Having built a boat I could have made some contributions to help pay back for the help you’ve given me.

There are a few different ways to protect the epoxy so you can see the carbon still.

2 part Uv protected polyurethane varnishes (I think you’ll like this one):

https://www.jamestowndistributors.co...MaAlwIEALw_wcB

Water based marine varnish:

https://www.totalboat.com/products/h...waAoXHEALw_wcB

More epoxy, but UV protected:

https://promiseepoxy.com/uvart?setCu...oaAvOVEALw_wcB



Personally, I’d probably go with the first one if I wanted longevity. If I didn’t care too much about the longevity and just wanted something quick there are even polyurethanes in the hardware store that would do the trick for a couple years.

[s/v Jedi]

Good news: after pushing Renogy a bit they have shipped the new solar panels and they are due to arrive on Monday

Also, we laminated the second beam. No peel ply wrinkles

[s/v Jedi]

Last beam laminated!

Also, panels arrived: https://www.cruisersforum.com/forums...ml#post3816505

[s/v Jedi]

Cut off the ends to get three equal beams ready for laminating the end caps. They are 85.5” long (2.17m) to support even larger panels in the future (like the 550W bifacials from Renogy, which are 2.27m long instead of the 1.90m of our 450W version… at the same width)

You can see the small sides are about twice as thick because of the unidirectional carbon fiber

[Lee Jerry]

Originally Posted by s/v Jedi

Cut off the ends to get three equal beams ready for laminating the end caps. They are 85.5” long (2.17m) to support even larger panels in the future (like the 550W bifacials from Renogy, which are 2.27m long instead of the 1.90m of our 450W version… at the same width)

You can see the small sides are about twice as thick because of the unidirectional carbon fiber

I'd be curious if you could put a micrometer on the skin thicknesses (assuming you haven't already put the end caps on), to whatever level of detail you feel like - 2 or 4 sides, 1 to 3 beams , one or two ends.

[s/v Jedi]

Originally Posted by Lee Jerry

I'd be curious if you could put a micrometer on the skin thicknesses (assuming you haven't already put the end caps on), to whatever level of detail you feel like - 2 or 4 sides, 1 to 3 beams , one or two ends.

Good idea. I used my Mitutoyo digital calipers which are accurate to 0.01mm.

After curing carbon fiber, core is 118.77 x 59.82 mm and incl. carbon fiber is 124.50 x 63.75. So the carbon fiber skin adds 5.73 x 3.93 mm.

Note that some spots of the web are a little thicker because of overlap where a fabric ends. I avoided those spots when measuring so that this error isn’t in the measurements.

This means the web is 1.97 mm and the flanges are 2.87 mm thick.

The outer surface of the flanges is completely flat, but the outer surface of the web is not because the unidirectional fibers come over the round corners, shaping the beam more like a train track. Because of this, the web has a higher resin to carbon fiber ratio because I was not able to remove excess resin as effectively as for the flanges.

Web:
1,198 gsm becomes 1.97 mm (608 gsm to build 1 mm thickness)

Flanges:
Unidirectional adds 915 gsm
2,113 gsm becomes 2.87 mm (736 gsm to build 1 mm thickness)

I believe that for the flanges the fiber to resin ratio is 50-50 by weight. Using the aluminum fin rollers, rolling lengthwise, is was able to squeeze all excess resin out, especially when rolling the unidirectional.

Another interesting detail: when using the fin roller perpendicular to the unidirectional fiber direction, this seems to redistribute/smooth the fibers into the laminate, resulting in a much smoother, better looking laminate.

I didn’t do the end caps yet. I’m first gonna drill holes in the center of the ends 5/8” diameter and 1” deep, then cast-fill these with epoxy thickened with high density filler. When that cast is gelling, I will laminate the end caps on using the same schedule as the beam web’s.

After all is cured, I plan to drill and tap 1/4” or M6 thread in there, to be used to hold the beams during painting as well as possible attachment points for awnings etc.

I’m currently working on the cassettes for the solar panels, getting final shape figured out, fitting the sliders, which fasteners etc.