Thread: Shade Sail Poles

Originally posted by Sir Stinkalot

Is there any trick to know about positioning the sails for best effects?

I think its best if they are off the ground.
Hope this helps.
Cheers, Allan

I have just measured the shade sail posts at work and they are 100mm X 100mm square posts with caps. Fittings are stainless and look like the standard boating eye hooks, shakles, turnbuckles and rope.
One post is 2.4m off the ground and is angled away from the sail and the other post is 4.6m, vertical and has a wire stay fixed back to a brick wall. When the posts were installed I did notice the hole was deep but I don't know the depth.
Bunnings sell the sails (5m X 5m x 5m) under Colorado (I think) branding so you may be able to get some info off the box.

I put up a shade sail using some 76x38x1.6 galv patio tubing. Had it powdercoated and it works a treat. The posts are 3.3m long, sunk 800mm into a 300x300x900 concrete footing. Gives me 2.5m clearance under the sail. They've been put in so that their 76mm axis is in line with the load.

The posts do spring a bit under tension but ithey're as strong as!! They're not going anywhere and I've been able to put on enough tension to get the sail looking nice and taught and totally eliminate any kind of flapping. Moves a bit, but not much.

I do think that 100mm posts are more than is needed for a domestic shade sail. I can appreciate the need for larger posts in a commercial scene where the sails are usually pretty big, but for the average 5mx5mx5m triangular sail or 3.6m square sail, the patio tubing is just the trick. Anything else, in my view, is over-specifying.....and expensive

Cheers



By the way, the Bunnings shade sails are Coolaroo brand. That's what I've got.

Forces on shade sails can be mysterious iindeed, and quite large, by way of example, my neighbour has had an 8mm eye bolt straightened in a squall, replaced it with a 12mm one, so far so good!.

Not too many structural engineers are comfortable designing them and as a result many seem to be over-engineered.
Basic principals are:

1) if it breaks it probably wasn't strong enough.

2) if it doesn't break, you probably could have saved some money and built it a bit lighter.

Cheers,

P

Sails should be angled for good looks - a dead horizontal sail does not look good.
Poles should be slanted slightly back from the sail for strength.

Tracer wires can be used to move poles further out or too allow attachment to walls that are further away from the corner of sails.

Note that it is more than the diameter of the pole that determines its strength - there are also different wall thicknesses.

Sir Stinky...

I have installed a couple Shade Sails in the past and can give you a couple of hints:

Pole size should be approx 100mm dia (galv post) with a 5-6mm wall thickness - I picked mine up from a scrap steel yard and only had to pay by the Kg.

You will need to sink it in at least 900mm (1000mm better) and fill it right up with concrete - when you set the posts in, lean them over on a slight angle, AWAY from the centre of the sail (if you set them straight, the tension that pulls them in will make them look crooked - but if you lay them over a little, they look like they are meant to be that way and they hold the tension better) make any sense?

Go for a sail with a stainless steel wire around the outside (proper custom made) - they can be tensioned almost trampoline tight - the off the shelf ones flap like crazy, and cant be tensioned much at all.

Custom made sails are well priced if you do all the work installing etc. (most will probably do a good price if you pay Charlie ASH )

I think I used 10mm Stainless fittings ?? whatever they are - they handle the Summer thunderstorms OK.

Dont fit turnbuckles to all corners - use one turnbuckle as security and use that 4-5mm "silver" rope (wind it through both the sail ring and your fixing point - several times) it acts like a tensioner, then tie it off. Turnbuckles will "Jar" and be quite noisy when the wind moves the sail up and down.

Aluminium sail track is nice to use if you want a flush finish against your house - cheap as chips from an aluminium supplier - you only need to specify what side you want to fit into the track, and your sailmaker will do his thing- and the big advantage is it spreads the load across the entire length (instead of just two points)

If you are fitting to your facia on you house - go absolutley crazy re-inforcing the back of it!!! you cannot have too much back there!! You need to have whatever fitting there - tied back so the tension is pulling on the roof joist/rafter, and not on the facia.



I hope some of this helps - Both sails I have done (one about 5m x 8m with sailtrack - one about 4m x 7m with high point up through a roof tile) are still shading nicely 6 years on.

Best of luck...

Dohboy....

G'day Stinky - There is a new sail maker recently moved in to the factory a couple of doors up from us at 71 Little Fyans St Sth Geelong. I reckon it would be worth paying them a visit for info.

Cheers - Neil

Ok,

I have managed to buy some posts on the cheap. I investigated 100mm gal poles with a wall thickness of around 3mm, I needed 4 posts at 4m meters each ..... the price was $25.00 p/m.

Not happy with this I went to the local demolition yard and picked up some old fire pipe for $5.00 p/m. The pipe is 110mm diameter with a wall thickness of 4mm.

As you can see from the photos it needs to be cleaned up. I plan on using the angle grinder and wire brush to remove the surface rust and then paint on a rust repellent and then a few coats of exterior house paint. I will need to fill the small holes with automotive bog.

Does anybody have any recommendation for the rust repellent undercoat? Also is there anything I can do about the rust on the interior of the pipe? I plan on capping the top so water can’t enter, or will it take so long to weaken the 4mm thickness that I shouldn't worry about treating the interior walls?

Thanks

Stinky.

Stinky, don't use the rapidset concrete, it's not actually structural.

Mick

Mick,

The bloody holes are so deep that I will need to mix up my own concrete the old fashioned way

Stinky,
Don't forget to weld a couple of cleats on the bottom of the post to give it more bearing area in the concrete.

Mick

Paint:

Have a talk to a galvanising company. The cost of getting stuff hot-dipped is often not much more than the cost of buying the paint, and the blokes that do galvanising will sand blast and "pickle" the posts first as well.

After galvanising, you can choose whether to paint or not.

Rusting from the inside:

Drawing a long bow here, but the weakest spot from observation is the line at ground, right where the concrete shrinks away microscopically, just enough to hold water most of the time. Recent experience says 4mm will be rusted through in 15 years in a coastal environment if not maintained. At least you can see it happening and shouldn't get a surprise!

A bit of epoxy tar on the below ground part should fix that for your lifetime at least.

Concrete

Take Mick's advice regarding cleats on the bottom, and make the footings twice as deep as you think you'll need. Last one I was involved in was not large, and engineer specified footings 1200 deep by 600 diameter, belled at the bottom.

It's the uplift you see ..........
or so I'm told!

Cheers,

P

Stinky,
to help prevent rust at ground level like P warns about, be sure to have your footings slightly above finished ground level and the concrete high around the post and falling towards the edges.

Mick

Stinky,

I'd look at getting a quote from a powder-coater. Could galvanise first too, I suppose.

What's your budget again??