mast / pole for wind gauge / direction

[Gina]

I'm looking into this whole mast business again. I'm fed up with my Heath Robinson rig of 6ft of 2" galvanised water pipe, then a 2m piece of 28mm water pipe and topping off .with a 3m piece of 22mm copper water pipe stuck into that. The copper pipe bends rather easily as copper is soft. I can't stay it properly as it's on the boundary of our property. I have one guy wire supporting it from the prevailing SW wind direction. Not only is it rather floppy but it's also heavy and a struggle to get up and down. (And I will keep modifying my wind sensors!!).

I have found what seems to be a reasonably priced web site for aluminium tube in the U.K. and they have a vast range of sizes in stock. The URL is http://www.aluminiumwarehouse.co.uk. Main snag is cost of shipping of £15 (15 UK pounds) plus VAT. But if I can get all I want in one go that isn't too bad.

They do two grades of aluminium alloy, one is designed for strength and for mechanical structures (6082T6), the other (presumably a softer alloy) more for decorative use and where the tube is supported (6063T6). I shall go for the former.

Next consideration is the size and wall thickness of the tube. I'm thinking of two parts, thicker at the bottom and thinner at the top.

Bottom section :- Aluminium Round Tube (6082T6) 1.75 in x 10 swg (44.45 mm x 3.2512 mm)
Top section :- Aluminium Round Tube (6082T6) 1.25 in x 16 swg (31.75 mm x 1.6256 mm)

Now I really don't know how stiff and strong this would be. Both sizes are available in 2.5m and 5m lengths. Using 5m for both sections would give nearly 10m (allowing for a sufficient overlap). I propose fitting the top section inside the bottom with suitable spacers. Alternatively, the mast could be in three sections, which I imagine would work out cheaper and lighter. No, I'm not suggesting 15m high Using shorter lengths. The permutations are almost endless.

Are there any structural engineers around or metallurgists with more information?

[Orion]

I used a washing line pole from Argos
Cat No 850/1415
And some other poles from B&Q
Slightly bigger than the ones supplied with the station
The bottom bit with the clamps came from an old amateur radio antenna
Would like to make it higher to clear the trees but would probably need planning permission.

[Gina]

Ah yes I've looked at B&Q, and just checked the washing line pole from Argos. The aluminium tube in a 2.5m length works out about the same as Argos's washing line and pole.

I'm thinking of setting up a second mast to check out my experimental wind vane, mounted on the corner of the goat shed. This would allow a higher mast but nearer the big trees. OTOH it would permit guy wires. It's difficult to know which of the two sites would be best, but I think a mast permitting a height of 8m above roof level and 10.5m above ground level would be in clearer air.

[Super-T]

I purchased a 6 Metre, 40mm square section, Aluminium length for the mast. I have it mounted on the upper deck so it is well clear of most influences. I've found it to be quite stable even in strong winds. Easier to mount also, being square.

[Gina]

That looks pretty good Terry

I've ordered some aluminium tubes and will be interested to see how rigid and strong they are. At the same time I ordered some shorter lengths of small tube for my wind vane project.