Apparently an air waves artificial reef is going to be placed on a Perth beach during September. 20 m by 2 m inflatable device that gets locked on the bottom allowing for prefect a frames. Sounds like it maybe a trial.

more?

There's not much more info. I found a face book page and the site for the device but there is no gov or council broadcasts to verify the program. still looking.

Not real confident on this! I've had a lot to do with oceanic pipelines in high energy coastlines. Problem being anything of any size like that sitting on the bottom will be undermined by shifting sand, result being it will wash up on the the shore after the first storm!

Let's hope it's a huge success and they get installed up and down the coast.

Yup. Who remembers the tyre/chain/crete efforts that were attempted in Perth mannnnnny moons ago? Same fate.

Yeah that's the concept. It popped up on face book as an event that runs from 21/09/15 to 21/12/15 at an undisclosed beach in the metro area. I hope it works but share the mentioned sentimen.

Supposed to be on the 21st of this month, Monday, has anyone heard anything else about the event and location

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jbshack said..
Supposed to be on the 21st of this month, Monday, has anyone heard anything else about the event and location

Cool I have the day off

Help me out here guys.

I know you guys can get solid waves south but for years now all I hear is how crap it is more often than not.
Winds? or a load of straight beaches ?

Would rock walls help improve things?

Lack of point breaks ?

Gotta know where to look, you dont hear me winging.

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DARTH said..
Gotta know where to look, you dont hear me winging.

Yeah sounds like a lot of local knowledge is required,but I hear it can be on and then the wind screws it cutting a session short? or poor timing?

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Macaha said..
Help me out here guys.

I know you guys can get solid waves south but for years now all I hear is how crap it is more often than not.
Winds? or a load of straight beaches ?

Would rock walls help improve things?

Lack of point breaks ?

Basically the beaches have straight banks, when there's a big swell it's onshore, and other than that we have 2 large islands offshore (garden island and Rottnest Island) blocking swell, plus they are connected by the shallow 5 fathom bank. The northern areas are protected by outer reefs too. All this makes it tough and you'll see our very regular 2m swells resulting in waist high waves.

Perth's crap Mac, as crap as crap can be. As busy as the Goldy but with really $hit waves. A series of smallish groynes would probably help but there's just so many frothing tuckfards and not enough waves.

There's a few reasonable waves down Pup's way but they're just OK.

Cape to Cape region is good, usually busy but good.
A couple of hours north of town can be good, fickle but good when it's on.

The rest of the coast north is pretty isolated with the odd epic reef ala Bluff and Tombies.

South coast is amazing, sharky, intimidating and lonely. Waves all the way from Augusta to the Bight.

It's a big joint, you get used to travel or you surf $hit with tuckfards.

this was discussed and this is cut and paste of a conversation that was running on a friends face book. The below makes sense to me, I'm far from an engineer however with the theory below is the closest I've seen to making sense of the idea.

Machaha
Perths Coast is pretty straight, not a lot of bays or coves with a couple of islands and a long reef 3 miles offshore that catches a lot of the available swell. There's certainly windows where it gets through, and North and South of the metro have some great days. The artificial reef South of Cott never really reached its potential but regardless of what you put down you still need swell, that's what gets robbed pbefore it reaches the beaches and reefs of the Perth Metro area. Autumn and winter can give you some great days but summer, forget it....many days of no waves.

anyway an engineers perspective below.

asked a prominent expert on artificial reefs / waves about this. I won't mention his name without permission but I'm sure he won't mind me posting his response. It's not feasible sadly. I patented something identical years ago and then did the experimentation and the reef cannot be flexible in any way at all or the mass of each wave above will push a dent into the air filled structure virtually identical in volume as the volume of water that is pushing down on it. As a result the wave will not break, or even shoal. So then you would need a totally rigid structure to force the wave to break and then the cost goes up to build and install. Also even if you did make the floating reef totally rigid then it would still tip downwards at its leading edge when a wave went to break on its front edge. Another thing is the ratio between the mass holding it down and the buoyancy pulling upwards. To be stable you'd need the mass holding it down to be several times the buoyancy pulling it up in order to be stable. This is because the net mass of the anchoring masses is in relation to water not air, since it's underwater. So with sandstone and concrete being double the mass of water you'd need 2 tonnes of rock for every one tonne of buoyancy just to break even. So you'd need between 6 and 10 tonnes of rock for every one tonne of buoyancy. At one tonne per cubic meter of water and air being virtually no mass, then you'd need 5 to 10 tonnes of rock per cubic meter or air filled hollow reef. This would have to be directly below each cubic meter of air. So effectively you would have a column of rock 5 to 10m below each cubic meter or air. It is now a solid reef.

No need to talk Perth up smicko!

Have you hatched a plan for the christening of your new board?

Nothin set in stone mate, will be too big and windy up north, maybe just Avalon or such. Shame it won't be big enough for where I was Fathers Day.

Maybe a groyne made from granite built at the correct angle to the sandy coast would create a wedgy right (or two when dug out by storms in winter) and a shortish (but fun) left pointbreak in summer..

Seem artificial reefs are a nice concept tho rarely produce anything substantial for surfing.

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mousetrap said..
Seem artificial reefs are a nice concept tho rarely produce anything substantial for surfing.

We have one here on the north end,it could have been great but ended up a flop,after a few swells it was burried in sand and you wouldn't even know it was there,great idea probably needed some work but sadly no more funds were made available.

Well what d'ya know? It was big enough after all

There was a thread on artificial reefs a while back.

The problem with groynes is how much they change the coastline.

Best idea that I can remember was the adaption of dust control measures used in mining and the existing technology used to protect underwater pipelines.

Like an anchored hairbrush just offshore. Would capture sand to make a bank and then let excess sand keep flowing laterally.

I've been thinking about the air cushion reef and too much flotation, which then led to why not pump it with water, then thought have a mesh outlet and pump it with sandy water until the whole thing fills with sand.
Anyway i found it easier to just move from Perth.

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Grevas said..
I've been thinking about the air cushion reef and too much flotation, which then led to why not pump it with water, then thought have a mesh outlet and pump it with sandy water until the whole thing fills with sand.
Anyway i found it easier to just move from Perth.

i would have thought pumping sand in it would have been better than air.


i would put massive concretes coloums into the sand in different heights to for a reef and that would allow the sand to move around on it,or it would just barnicle up

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Surf69 said..
this was discussed and this is cut and paste of a conversation that was running on a friends face book. The below makes sense to me, I'm far from an engineer however with the theory below is the closest I've seen to making sense of the idea.

Machaha
Perths Coast is pretty straight, not a lot of bays or coves with a couple of islands and a long reef 3 miles offshore that catches a lot of the available swell. There's certainly windows where it gets through, and North and South of the metro have some great days. The artificial reef South of Cott never really reached its potential but regardless of what you put down you still need swell, that's what gets robbed pbefore it reaches the beaches and reefs of the Perth Metro area. Autumn and winter can give you some great days but summer, forget it....many days of no waves.

anyway an engineers perspective below.

asked a prominent expert on artificial reefs / waves about this. I won't mention his name without permission but I'm sure he won't mind me posting his response. It's not feasible sadly. I patented something identical years ago and then did the experimentation and the reef cannot be flexible in any way at all or the mass of each wave above will push a dent into the air filled structure virtually identical in volume as the volume of water that is pushing down on it. As a result the wave will not break, or even shoal. So then you would need a totally rigid structure to force the wave to break and then the cost goes up to build and install. Also even if you did make the floating reef totally rigid then it would still tip downwards at its leading edge when a wave went to break on its front edge. Another thing is the ratio between the mass holding it down and the buoyancy pulling upwards. To be stable you'd need the mass holding it down to be several times the buoyancy pulling it up in order to be stable. This is because the net mass of the anchoring masses is in relation to water not air, since it's underwater. So with sandstone and concrete being double the mass of water you'd need 2 tonnes of rock for every one tonne of buoyancy just to break even. So you'd need between 6 and 10 tonnes of rock for every one tonne of buoyancy. At one tonne per cubic meter of water and air being virtually no mass, then you'd need 5 to 10 tonnes of rock per cubic meter or air filled hollow reef. This would have to be directly below each cubic meter of air. So effectively you would have a column of rock 5 to 10m below each cubic meter or air. It is now a solid reef.

Whatever how you fill with bags ( air or sands) they needs to be founded on an geological layer of heavy materials like gravels . I explain: in most situation beaches stretch was originally river mouth so there is layers of gravels where river had been flowing during glaciation period.
So off shore of some beaches there is gravels banks ... this is the place to cast the sand bags or Chrispy's concrete column to enhance the nature which is providing the A frame wave to shore.

Slightly of topic but..

I have always been of the opinion that the sand in Perth especially around my area (Mindarie to Hillarys) tends to wash south but never seems to make it back north again due to the marinas of Hillarys, Ocean Reef and Mindarie Im not sure if that correct or not but when you consider Quinns beach has been dumping thousands of tones of sand onto the eroded beach over the last few years, could that extra sand be the reason the northern beaches are finding record levels of sand

Obviously the Airwave reef system was not trailed anywhere Or if it was, its a best kept secret..

I really do think some sort of solid artificial reef structure would be great in local Perth. The swell that hit the coast on Sunday seemed to be wasted at most spots TBH

I just cant see a 20 m anything breaking up Perths straighthanders