I have been getting quotes too.... not cheap but the sail sample I liked best was Mandura Sails - heavy duty fabric and narrow welded seams... approx $35m2 and 500 a post.... I will keep watching thi spost to see if there is any recomendations from site members....

Gidday Old Salty and Mr Winta,

I used to work for a firm that manufactured, supplied, and fitted shadesails and awnings. i was with them for many years, and can offer advice if you wish. (you're welcome to PM me.)

The main thing with shadesails is that they are only as good as the footing that holds the post!

A shadesail moves up and down with the wind, no matter how much tension they are under. This movement imparts lateral loading on the posts or attachment points. (Unlike patio or fixed structure that simply has vertical loading on the posts.)

This lateral force is trying to pull the posts inwards, and the only thing that stops this occuring is a bloody great lump of concrete at the base of the post! If you're in sandy soils its even worse. (which covers most of Perths flat locations!)

In such situations, I made sure the post went in the ground at least 1mtr, with a minimum of 10 x 40kg bags concrete. If the sail is small, or the ground conditions are compacted or 'tight', then less concrete is ok, but I'd still make sure the post is bloody deep.

For post sizes, we used 100 x 100mm or 90x90's, with 3-4mm wall thickness. Anything less and you get too much deflection with wind.

Fixing to a house or brick wall can also be fraught with danger! I have seen a few disasters, and some have created extensive structural problems that I couldn't fix. Like wise the posts, a brick wall is built for sustaining vertical loading. ie a static huse roof sitting on it. They are not designed for a sideways pulling force like a shadesail thats flapping up and down with the wind. If its a single leaf brick wall, dont even think about attaching a sail to it! A double brick house wall can be done so long as they are tied together with the loops brickies use in the building stage. Even then, I'd attach a post to the side of the house, with 3 fixing brackets. 1 at the base, 1 about a third of the way up, and the other 3 or 4 courses down from the top.

Always try and get 4 fixing points for the sail, with 2 diagonally opposing points up 1mtr higher than the other 2 points which would be lower by 1mtr. This height differential makes the sail into whats known as a 'hypar' shape and looks good, but is also functional. With tnesion on the shadecloth, it pulls the midpoint of the cloth up to 2 points, and also down to the other 2 at the same time. This holds the sail sturdier in the wind and reduces flap.

A triangular sail or one with only 3 fixing points is largely a waste of time. You end up with a 'g-string' of a sail, with stuff all coverage, unless you're just filling in a corner of a courtyard or something similar.

There are a number of good shadecloths on the market, and most have a sunshade factor of around the 95% region. Over the years, I used a fair number of types, and came to the conclusion that they are all pretty good for the purpose.

What does make a difference is how they are cut, and how they're joined. I'm of the opinion that the jury is still out on welding of shadecloths. (If the operator runs of even slightly, or the temp is even a smidge to hot, then the cloth is weakened considerably. This is my opinion only, and it depends entirely on the operator.) Not many fabricators Australia wide use this method. Most use standard stitching, but this has a limited lifespan. Whilst the cloth has a 10 year pro-rata warranty, the stitching isnt covered, and depending on location, they come apart at the seams in about 7 years. There is a thread out called TENARA, and this has a 15/20 year UV warranty, and  some fabricators are now using this.

Old Salt, a concern I have on the size of your sail is the 9m length. You will have bugger all coverage if it is only 4m wide! (unusual m'ments 9x7x4x1, so I'm guessing the shape). From the corner fixing points, straightaway you lose .3 of a meter for the turnbuckle tensioners. On top of this, the shadecloth has to be shaped in a catenary curve. The greater the distance between points, the greater this curvature should be to retain tension on the cloth. eg. for a 4m length, 5-6% should be cut out, for 6m 8% should be cut out of the middle, and for a span of 9m  then realistically the curvature should be in the region of 12%. That equates to approx 1m of shadecloth cut out in the middle of the 9m length. add this to the 300mm for the tensioners and your missing 1.3m of shadecover in the middle of the 9m side. You can counteract this by positioning the posts further back, or adding another fixing point in the middle.

This is a basic overview.

Hope it helps.

Cheers.

Browny.

Top advice that!!  Put a few in a couple of years back with 4 x 4m posts (1m was in the ground) and just over .2 m3 conc in each hole and they were solid.  Windy day in Exmouth and you could see the posts move with the flap of the sail even though they were tensioned bloody tight.  These were to cyclone ratings and had 2 lengths of rio bar welded to the 100x100 to anchor the posts in the conc.  The advice on anchoring it to your house is spot on!

Ask an expert and you get top shelf advice, many thanks browny I may just send you a pm in the coming days with a pic of what I was attempting to accomplish. Looks like I will be ripping up some big pavers and digging 4 big pot holes. Sounds like I wlll be parting with 4k approx.

Regards, Old Salt

Hey Browny i have attached the image to my original 1st post, bear in mind its a very old google maps image and there is quite alot more paving around the pool now to the pool fence 500x500 stone blocks, the trees i have planted on the western side of the pool will provide some nice cover in summer when fully grown. The area that gets the most use is the spa end and the deep end and these are the areas i will be focussing on sheltering. just out of interesting is evaporation reduced by much once a reasonable shade sail is fitted? I suspect not?

Cheers Old Salty

Which is why shark bay has massive salt harvesting - warmth helps but the breeze is the key

Howdy Odl Salt.

That image helps imensely!

2 things spring immediately to mind.

A) With a long narrow shape like you propose, there will be very little coverage! From my initial post, you'll see that each of the long sides will have about 1.2-1.3m of curvature taken out of the middle. (and when tension is applied at the corners, the cloth will pull in further in the middle.) This will leave a narrow strip (approx 2m)  of shadecloth down the length of the pool. To make matters worse, at the end where you show 1meter, this in effect will only have a strip of approx 400mm wide to start with. In effect, your sail will be like a giant g-string. The effective shade will be next to none!

B) With the long side facing North, this leaves the narrow strip to try and give shade whilst the sun moves East to West. i.e. you'll have shade directly under the sail from about 11.30 - 12.30 ONLY!. The rest of the time the shade will be elsewhere as the sun moves. Mornings will see no shade at all over the pool, as the shadeline will be pushed into the trees. You'll then have a brief period of shade, followed by the shadeline moving towards the house as the sun progresses towards the West. If your trees are tall enough, they may impart some shade.Again IMHO its a waste of money for effective shade in this design.

There are 2 possibilities to create better shade. 1 would be to add an extra post out near the southern corner of the umbrella or deck area. This would greatly enhance the effective shade over the pool. It would make the sail a very large one, so the footing sizes would need to be MINIMUM 10 bags concrete. ( I'd look at hiring a post hole digger and going 1.5m deep x .6 x .6 as a start point.) With the post near the southern side of the deck, you could also then add another two posts along the halfway points of the 8 and 9m sides. This would create lesser loadings on the footings, and greater aesthetics with alternating high/low effects on the sails. You will always end up with a few gaps in the middle between multiple sails, but it can look very effective, and in reality for the size you are talking about will be far more functional.

Another possibility would be to keep the original shape, but stick with a traditional pergola type structure that doesnt have curvature or flap.

ps.. Just another caution regarding the use of extended cables from a post to a sail like in your southern most post: this method allows a lot more 'play' in the sail. Without being directly fixed to the post, you will have a lot more up and down movement in the sail. I would make this point at 3.5m high or there-abouts to impart a greater height differential. This height will reduce the noticeability of the movement, and will give a greater feeling of space/ambience under the sail. The greater height difference will also hold the sail tighter when the tensioners have loading applied. alternatively, move the post closer to the pool and have the sail attached directly to it.

Apologies if a lot of the above sounds like sending a negative message, but with shadesails, it was a product that had less customer satisfaction than any other we produced (when I was at the firm.). I am a firm believer in solving problems up front, so that people have a realistic expectation of how a product will perform, and its limitations. This way an educated buying decision can be achieved without the nasty surprises when its delivered!

Cheers salty.

Hope this helps.

 edit: ALSO, you'll have to have all separate posts. Boundary walls are all single leaf in my experience. If you tie the sail to this wall, you WILL have problems!! You'll have to allow for full posts and footings to tie to.

Browny.

A lot of councils approvals for sails and many of them require engineering drawings to build anything.

 Many thanks again Browny the advice you have given makes perect sense and is highly appreciated. I think i may settle with 4 -5 posts and two sails at different heights for asthetic reasons. What i also need to now consider is irrigation pipe locations, footing placement and the neighbours opinion on the matter. Seriously council approval for shade sails???

Regards Old Salty

Jamie's correct Ole Salty. Most councils require approvals. The only one I know of that dont is the Rockingham Council, but that may have changed.

All councils have different regulations too. Some require planning approval first and then even charge another fee for building approvals! Some wont look at it without signed off engineered drawings as Jamie said.

Basically, they are deemed a pergola under the building bylaws. Some councils will require a signed document from every neighbor saying they're ok with you erecting the sail.

The other thing that you'll need to check before you go ahead is your councils requirements on how close to the boundary you can place a post and the height of said post. In the past I've had differing advice ranging from .5m from boundary and no higher than 1.6m, and varying up to 1.2m from the boundary with no height restrictions. You can also visit the same council and talk to 2 different people and get 2 differing opinions. Its a minefield! The worst case i had was with Vic Park council where they took 9 months to determine if a sail could be erected, only to come back and refuse it with the reason...'it could be seen from the road'!!!! no bullshit!  When I queried it on behalf of our client, the jumped up little council dick said that if they want, they could stop a resident putting up a hanging basket if they want!  Other P.I.A. councils are Swan, Stirling, Joondalup.

we always tried to do the right thing with council approvals, but some are very difficult to work with. In some ways i can see why 90% of shadesail manufacturers dont mention council approvals at all and just leave it up to you. It is up to the owner to know or find out what can and cant go in their property. Problem is if you go to sell it, and there's an unregistered structure, the sale could fall thru. Also, if ya neighbors complain, council can demand you take it down and then its a complete waste of money.

Anyway, good luck with the project Salty, and dont hesitate to PM me if i can help.

Browny.