Rolling pool cover

[Iain_lyons]

Hi all, please help! I have an in ground swim spa and have failed to make a rolling pool cover. The idea was aluminium box sections 75mmx50mm 3mm thick. This would contain insulation foam and roll over the pool. Unfortunately the aluminium is too soft and the deflection is such that it drags its belly on the decking and is impossible to move when I put decking boards on top.
I need to strengthen the frame. Please help!!

I hope that bolting stainless steel 316 box section 100mm x40mm x3mm to the long edge will stiffen it up. I need to ensure minimum deflection of <10mm. Currently it is 40mm deflection!
Some info: the frame is 5400x3000mm it sits on 80mm castors with 30mm clearance underneath. It will be covered with hardwood decking (heavy) I think 40kg/m2. I have attached a photo of the frame and a sketch.

Do you know if this will work? Any other thoughts?

Thanks everyone

Iain

 

[Pat ex]

You're hoping to pull something over 700Kg over the pool on castors?
Have you looked at commercially available covers and compared the price and ease of use?

 

[Iain_lyons]

Thanks, there are massively expensive commercial ones. They uses much larger aluminium box sections, but I wanted to keep the overall height as low as possible.

 

[cdbe]

Put castors down the centre and make a drop in beam/channel for them to run in.

 

[Iain_lyons]

Thanks, I have castors in the middle already so it is solid when it is on top of the decking. The problem is rolling on and off the pool as there is nothing to support the central castors. Thanks for ideas though please keep them coming!

 

[freddiemercurystwin]

He means you drop in a (removable) beam over the centre of the pool when you want to drag the cover across.

 

[Iain_lyons]

Ah, I see… makes sense. unfortunately as the pool edge is pretty flush with the decking, it won’t be possible to put a support beam there. The beam would obstruct the rolling of the cover. It would somehow have to be flush with the top of the pool, and I’m not sure how I could secure that. Not sure what would be strong enough yet low enough in profile.

I’m hoping to reinforce the frame with a steel beam along the long edge to prevent the sagging that is currently the issue.

 

[Harry Bloomfield]

If you can afford a bit of height - A few posts fixed along the both sides of the long edges, with a stainless wire from post at one side, down to centre, then back up to far post, will help support the middle when taught.

 

[Iain_lyons]

Thanks, I agree this could support the centre from sagging. However, I would need to keep the height as low as possible so this is a sadly not an option.

Does anyone have any suggestions for the stainless steel box section I had hoped could work?

Thanks for all your suggestions.

 

[cdbe]

Why can't it fit flush:

If it's bending like that under its own weight then God knows what will happen with half a dozen people dancing on it at your next party.

 

[Iain_lyons]

Thanks for the diagram, this would fit and could work!! It’s not the neat solution I was hoping for ( having to fit/lift off 2 beams to use the pool) but am grateful for your thoughts. FYI, when the pool cover is over the pool or on the decking there are screw down brakes along the long edge and it is solid as a rock!

 

[Harry Bloomfield]

hanks for the diagram, this would fit and could work!! It’s not the neat solution I was hoping for ( having to fit/lift off 2 beams to use the pool) but am grateful for your thoughts. FYI, when the pool cover is over the pool or on the decking there are screw down brakes along the long edge and it is solid as a rock!

Another wild idea - what about floats to help support the centre?

 

[Iain_lyons]

Thanks again, love the thinking! Probably not able to provide the lift needed to support the weight while rolling on/off the pool though.

Anyone with any structural engineering skills?!

 

[Higgy28]

Your bending in the long direction will be entirely dependent on the long beam cross section. If you're determined to keep the design you need to stiffen those members. Could you replace the long edges of the frame with a box section of thicker aluminium or even steel?

 

[freddiemercurystwin]

Does it only sag with the decking on top?