Artificial reef - airwave

simba's picture
simba started the topic in Saturday, 11 Aug 2018 at 6:39pm
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simba's picture
simba commented Saturday, 11 Aug 2018 at 6:39pm

.

simba

spuddyjack's picture
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spuddyjack commented Saturday, 11 Aug 2018 at 7:35pm

Really interesting read Simba. There seems to have been considerable research done hitherto. This would certainly cut the lunch of the wave pool wet dream brigade - at least to some extent. Would be marvelous if the inaugural project worked well and encouraged more councils to get on board. Victor Harbor council (SA) should be approached to address the less than mediocre Middleton-Pt Eliot stretch - that poor bloody demographic of surfers need a decent break - literally and metaphorically. No doubt there are countless possibilities around the globe. Hope the crowd funding comes together quickly.

Stay salty

Nick Bone's picture
Nick Bone's picture
Nick Bone commented Sunday, 12 Aug 2018 at 2:00pm

I get excited about a project like this, as there would be a excellent beach at home for this but it makes we wonder that if it did work as well as they say i.e a straight 6ft swell we get rather regularly, how crowded it would get. What i mean is, the places that these would suit would also get extremely busy as there wasnt much option to begin with?

I am the bone

indo-dreaming's picture
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indo-dreaming commented Sunday, 12 Aug 2018 at 3:04pm

Great if they can get it up and going and like to see it succeed and i think we have talked about similar/same idea here somewhere.

But skeptical it will work that well.

1. Seems its full with sand but also air? any air will create buoyancy making it less stable and easier to get moved around by waves and currents.

2. We already know from the Gold Coast sand bags objects like big sand bags just sink if sitting on sand as the water/currents/wave action just undermines the bags.

On a solid bottom like coffee rock, could be more successful though.

blindboy's picture
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blindboy commented Sunday, 12 Aug 2018 at 2:43pm

I agree Indo. Having seen the size of the boulders moved around, I'm struggling to imagine how it could be secured well enough to survive the kind of storm conditions we get on the east coast.

Laurie McGinness

simba's picture
simba's picture
simba commented Saturday, 18 Aug 2018 at 6:11pm
Eugene Green's picture
Eugene Green's picture
Eugene Green commented Saturday, 18 Aug 2018 at 10:54pm

Bunbury? That’ll be the second time an attempt at making an artificial reef in WA is unsuccessful due to a lack of swell in the chosen area. More money down the drain and will make it harder to fund any future plans for man made waves at better suited sites.

stunet's picture
stunet's picture
stunet commented Sunday, 19 Aug 2018 at 8:01am

Not a chance in the world it can work.

spuddyjack's picture
spuddyjack's picture
spuddyjack commented Sunday, 19 Aug 2018 at 10:12am

Why Stu? Poor overall bathymetric factors for the project at Bunbury or poor design or both? Please elaborate.

Stay salty

lampy's picture
lampy's picture
lampy commented Sunday, 19 Aug 2018 at 10:44am

Just doing a few basic calculations, If you submerge 300 m^3(just a guess of how large the dome would be and the volume) of air under seawater the force to hold it on the seabed is 307.5 tons. That's a lot of force to keep on the seabed without taking into account the swell force which will deform the dome and create localized elevated forces.
He is stating he will use 12 helical sand anchors. They are going to have to be very big to hold down 307 tonnes

lampy's picture
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lampy commented Sunday, 19 Aug 2018 at 10:45am

Wonder if he has done some scale models? doesn't seem to be much info on his testing

simba's picture
simba's picture
simba commented Sunday, 19 Aug 2018 at 11:14am

It might possibly be filled completely with sand.........whether thats enough to hold it down is the question.

simba

Craig's picture
Craig's picture
Craig commented Sunday, 19 Aug 2018 at 11:33am

No way that will stay attached to the ocean floor during a big storm.

blindboy's picture
blindboy's picture
blindboy commented Sunday, 19 Aug 2018 at 12:50pm

....... it could be a thoroughly deflating experience!

Laurie McGinness

stunet's picture
stunet's picture
stunet commented Sunday, 19 Aug 2018 at 4:37pm

@Spuddy,

One of the biggest misconceptions about wave mechanics is that wave shape is solely a product of the bathymetry below the wave. It's not. Equally as important, and very often overlooked, is the bottom topography immediately offshore from the wave - otherwise known as the 'run up'. The run up primes the wave for breaking, stands it up, focusses energy etc.

The importance of the run up increases as the wave period increases, because the swell feels the bottom earlier. Put a structure on the bottom with no run up, in a zone of long-period swells, and you'll get an undersucking, unsurfable surge.

So perhaps the intention is to have sand build up around the structure and create a run up? However, sand wont lay against something that's moving, even a few millimetres of movement, so it simply won't happen.

I like the out-of-the-box thinking, however, without sounding too harsh, the Airwave is destined for the Great Pacific Plastic Patch. I hope it doesn't sink all goodwill for artificial reefs 'cos there are some good ideas out there.

spuddyjack's picture
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spuddyjack commented Sunday, 19 Aug 2018 at 5:01pm

@ Stu,

Many thanks for that cogent explanation Stu. I had given no thought to the bottom topography run up factor whatsoever. Hopefully other good ideas will emerge to factor this in accordingly in future designs.
Cheers,
Spuddy

Stay salty

tubeshooter's picture
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tubeshooter commented Sunday, 19 Aug 2018 at 6:07pm

Scale modelling is one thing , but that is done in static environments that don't reflect the nature of the areas they would be placed, or the volumes and forces that the structure would be up against. Wet sand is far from solid and anchoring anything of any mass to it will take more than a few sand anchors. The opposing forces between the buoyancy of the air and the anchoring system will be in constant opposition to each other and will create many stress points. Highly skeptical.

udo's picture
udo's picture
udo commented Sunday, 19 Aug 2018 at 6:39pm

This is this blokes second crowdfund / kickstarter try for a Artificial Reef ?

tubeshooter's picture
tubeshooter's picture
tubeshooter commented Sunday, 19 Aug 2018 at 7:07pm

I wonder if he's called Dirk yet. I bet he hasn't factored in the little things , like councils will need full environmental paperwork cleared by seagrass and sand worm experts, sand movement problems leading to potential erosion, unretrievable broken bags half swallowed by sand, community opposition , commercial fishing {beach haulers}, hippies , , ,,, need I go on?
Tell him he's dreaming.

David Brown's picture
David Brown's picture
David Brown commented Monday, 20 Aug 2018 at 3:06pm

Nice idea!
It will be great for both adults and children to enjoy their surfing lives.

David Brown
shaka-surf.com

andrew-pitt's picture
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andrew-pitt commented Monday, 20 Aug 2018 at 10:52pm

Troy - best wishes - hope it gets up. Tweak it, you'll figure it out.
Found the 2014 Kickstarter campaign.
Anybody find the link for the 2018 campaign?

andrew-pitt's picture
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andrew-pitt commented Tuesday, 21 Aug 2018 at 3:08pm

The 2018 Kickstarter link is here...
www.kickstarter.com/projects/airwavesurfreefs/airwave-the-worlds-first-i...

Stu - are you going to run a story on this?

There's one key reason why every surfer should back this project, via Kickstarter.

frog's picture
frog's picture
frog commented Tuesday, 21 Aug 2018 at 7:57pm

Some merit if it is placed to support an existing sort of semi closeout bank. If it creates a peak and take off point to lead into existing angle where some peel and some do not. But on its own in a real closeout it might end up as a very brief takeoff followed by a major slamming shorebreak. The ability of a structure to alter the angle of a wave is determined by its length relative to wavelength. The structure needs to be multiples of the wavelength otherwise it surges past with no time to shift. The design should be long drawn out eclipse pointed out to sea, not a circle. The smaller it is the less chance it wiil work. Any good reef or even small bombie that creates a good wave is much larger than meets the eye.
But I think the pluses are using sand to weight it and air to add easy volume and it being soft and mobile. The goal is the great but I would need to see videos of the testing to see if the round design would work better than my current view.

Frogg

truebluebasher's picture
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truebluebasher commented Thursday, 13 Jun 2019 at 2:24am

Thanx to factotum for link via "More from the mind of Greg Webber"
https://www.swellnet.com/news/swellnet-dispatch/2019/06/06/more-mind-gre...
Here's factotum's News Link for "Bunbury Airwave"
https://thewest.com.au/news/south-western-times/artificial-surfing-reef-...

Roadkill's picture
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Roadkill commented Thursday, 13 Jun 2019 at 7:11am

And we can take a self driving car to the Uber Air flying car port....a quick 30 min trip and we can surf barrels. The future is coming..yeah nah.

Greg Webber's picture
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Greg Webber commented Thursday, 13 Jun 2019 at 10:35am

Well unless I missed the comment there is only thing that stops this from working. It is what happens to the entire structure when a wave passes over the top of it. Anchoring is no issue, the sand bag base is fine, you just need a certain, work-out-able ratio of mass pulling down to buoyancy lifting up for it to be quite stable.
The key problem is that if the air filled bag does not have significant rigidity, then the wave will just push the bag down in that area, just like filling a surfmat with air and pushing down at one end. Each wave weighs a lot, we all know that, water weighs a tonne per cubic meter so without getting smart with numbers there will be lots of tonnes pushing down on the bag over a relatively small zone, no more than a few meters from the front to the back of the wave. It'll be kind of like getting one of those back rollers on top of the surfmat that's lying on the ground, and rolling it along the length of the matt. It will depress the air filled structure almost entirely to the floor just below the wave, or in the case of the air filled bag, to the sea bed.
Then if you were to put a strong sheet of plywood on top of the matt then you could roll along the entire matt without depressing anything at all. It's the load-spreading effect.
So if the air filled reef doesn't have the equivalent of the sheet of ply, (which would then be reinforced concrete over the entire structure) then it will definitely deform and dent in about as much as what the cross-section of the wave is. A 2m wave will make a dent in the bag like an up-side-down wave shape. And as a result the wave won't break but it will certainly slow down and die out quickly as the drag kills the wave energy. So what you really end up with is a hollow concrete reef, that doesn't need an air-filled bag, nor sand bags, and has next to no novelty to it since it's obvious to most engineers, and so would not be very patentable. If the designers can explain clearly what the upper air bag is made of and how it will not deform under the mass of the waves then that's what they can counter this argument with. The scale testing can work quite well but doesn't indicate the real relationships that would exist at full scale, since the bag they will use will have enough of it's own rigidity just due to the material it's made of being just stiff or inflexible enough to handle the mass of a 2" wave.
I know, I've experimented with the exact same idea just under 10 years ago, and was so disappointed that it failed, but then also surprised that i hadn't realised the flaw before making it. The stiffer the air bag got in my experiments, the better it worked but then when I realised what that would equate to a full scale then I knew it was going to require either significant air pressure and a moderately strong surface material, or no air pressure and a very strong material like reinforced concrete. And I cannot see any system of retaining very high air pressures in their full scale design. But their scale model has an air inlet for compressed air and this might be what is making them think that it will work. If that's done with the full scale then the pressure required will be huge and then if it gets punctured then watch out.

truebluebasher's picture
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truebluebasher commented Thursday, 13 Jun 2019 at 2:09pm

It's very thoughtful to spare your valuable insight with swellnet Greg!
I'm sure Troy from AirWave is much the wiser should he tune in. (Most excellent!)

Be great to solve the riddle of the floating sacks in China's Wavepool.
The XL Pool seems devoid of Bathymetry...
https://i1.kknews.cc/SIG=3lfi3aa/ctp-vzntr/prs23q57709r47r2oq5roso18440q...

*We can see that Rice is everywhere & sand is a foreign luxury to this site.

2nd frame we see the wave train in action...
https://www.youtube.com/watch?v=2saaZFuWNrw
See how the Bathymetry is depressed as if the contour has released or escaped.
Now various sized weighted 'black sacks' have 'escaped' to float 'n' bump about.

Perhaps the wave train action has teased these floating sacks from the liner.
Contour sacks are clearly too heavy to be air & too light if sand! (Half Soaked Rice?)
Anyhow! It actually looks really bad & that can't be good!

truebluebasher's picture
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truebluebasher commented Friday, 14 Jun 2019 at 7:53am