Construction of solar arch?

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RJJ

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Hi all

For a solar arch - 25mm tube - I'd welcome thoughts please on:
- wall thickness 1.5mm? Or should it be thicker?
- 304 vs 316?

Thanks
 
To a degree it depends on size of boat . I used 25mm for mine but I have seen plenty of arches or gantries made of thicker tubing on bigger boats.
 
RJJ said:
Hi all

For a solar arch - 25mm tube - I'd welcome thoughts please on:
- wall thickness 1.5mm? Or should it be thicker?
- 304 vs 316?

Thanks
Click to expand...
A lot depends on design and height, with no bracing that might be a bit skimpy. lots bracing you could do it in 2mm solid bar :)
Building a bimini frame at the moment for a mate, 30mm x 1.5 CHS stainless which feels OK enough on 4 legs, will be solid once the top is on anyway.
 
Definitely 316.

As others have said, diameter depends on size of your boat. But 25mm will be a bit flimsy. OK just for solar panels, but not much else.

Arches are so useful that you soon find yourself using them for all sorts of other stuff. I use mine to pull the dinghy out of the water at night, as a brace for taking a leak over the side, as grab rails for boarding the boat, to suspend a deck light, as a mount for an anchor and stern light, as a support for a bimini. The list goes on.

Having said that, if performance is more important than practicality, then a lightweight 25mm arch is adequate. Suggest you don't go for those rigid polycrystalline solar panels. Better to roof it with thin plastic then attach an array of the flexible panels. It will be much lower profile, lower windage and you can more easily replace individual panels as they wear out.
 
dansaskip said:
To a degree it depends on size of boat . I used 25mm for mine but I have seen plenty of arches or gantries made of thicker tubing on bigger boats.
Click to expand...
Thanks, it's only to hold the solar panels and nothing more (no radar, windgen, dinghy etc.).
 
GHA said:
You must be Mystic Meg if you can say that knowing absolutely nothing about the design, height, weight/size of panels. connections to deck.....

I have a piece of string, is it strong enough?? ;)
Click to expand...

If he makes it out of 100mm diameter x 25mm wall thickness it won't be any good if he sticks it on with chewing gum, one assumes that it will be suitably affixed.

I have a pair of 100w panels on a gantry made from 25mm x 1.5mm 316, it is perfectly adequate. Previous to that, there was a single panel mounted on top of a 25mm tube that was u-bolted to one of the pushpit uprights, it had been there for decades.
 
PaulRainbow said:
If he makes it out of 100mm diameter x 25mm wall thickness it won't be any good if he sticks it on with chewing gum, one assumes that it will be suitably affixed.

I have a pair of 100w panels on a gantry made from 25mm x 1.5mm 316, it is perfectly adequate. Previous to that, there was a single panel mounted on top of a 25mm tube that was u-bolted to one of the pushpit uprights, it had been there for decades.
Click to expand...
Not that there was any doubt, but that just confirms you really have no idea about even the basic concepts of structural analysis . It's not helpful to make definitive statements about an unknown design with no knowledge of how structures and forces work.
 
GHA said:
Not that there was any doubt, but that just confirms you really have no idea about even the basic concepts of structural analysis . It's not helpful to make definitive statements about an unknown design with no knowledge of how structures and forces work.
Click to expand...

Yawn, back to your usual obnoxious self
 
RJJ said:
Thanks, it's only to hold the solar panels and nothing more (no radar, windgen, dinghy etc.).
Click to expand...
May be true on day one, but that platform will start to look real handy next time you have something to install! I'd probably size it with an assumption of radar and windgen being attached. They also seem to be used for storing SUPs and similar these days. I can't imagine it would make much difference, stainless is probably way too strong for the requirement anyway, especially given you'll probably have 4 support posts.
 
25mm x 1.5mm 316 tube, a pair of 100w panels and an emergency VHF antenna, nothing complicated, no feats of fantastic engineering, no multitude of brace and/or guys and supports. Been there 4 years, regularly used as a hand rail for getting on and off of the boat or for leaning on when underway.

Solar Arch.png

If we want to hang the dinghy off the back or add other things, we design something different and use appropriate materials. Swing out davits, etc, so bigger tube, built into the pushpit (not quite finished in this picture) for additional strength.

20190226_163315.jpg

Horses for courses, the OP said he only wanted to mount his solar panels.
 
I based mine on Paul's design having spoken to him. Used 25mm x 1.5mm tube. Added an extra smaller diameter support from the pushpit to the toe rail because it only has two legs either side and there was a bit of flex of the pushpit where the rear leg of the gantry is clamped on. Supports 2 x 100w panels. 20210402_122850.jpg
 
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Surely a pedant would say that the thickness will depend on the spec you buy? That was almost the opposite of pedantry, it was a sweeping generalisation
 
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