Avoca's Artificial Reef!
Stuart Nettle March 22, 2010
Last Friday I attended the 7th Artificial Reef Symposium at Bondi.
The invitation came as a surprise, for as readers who have followed this column will know I'm a doubting Thomas when it comes to artificial reefs.
Dissidence aside, it was an informative day. One of the things that I learnt - and it came as no surprise - is how hard it is to get an artificial reef built. The difficulty not just in the expense but also in gaining approval; there are many layers of bureaucracy to appease, many hoops to jump through, and finally, many public fears to be allayed before anything will be signed off.
I also learnt how existing artificial reefs were constructed; the meticulous modelling to predict potential side-effects, and the precise to-the-metre placement of the materials that comprise the reef. The near-shore zone is in a permanent state of flux so an understanding of how the reef will impact the surrounding areas is a necessary step in the approval process.
On Saturday I read about the plans to scuttle HMAS Adelaide at Avoca.
For those not up to date on the HMAS Adelaide here's the skinny: the Federal Government has approved plans to bung the decommissioned warship full of dynamite and scuttle it off Avoca Beach with the purpose of creating a dive site. The boat will lie 1.8 kilometres offshore in approximately 30 metres of water. At it's shallowest point it's estimated the boat will be 10 metres from the water surface.
There are many similarities between the 'artificial reef' that will be created by the scuttled ship and those proposed for surfing: both are amenities for coastal users, both are made from materials foreign to the ocean environment, and both are located in the active near-shore zone where they interrupt the flow of sand.
Although the outcome and potential environmental affects are similar the perception of each is vastly different. Artificial reefs for surfing are considered dangerous, unwarranted and questioned at every turn. And rightly so. As I mentioned earlier, anything dropped in the near-shore zone, especially near an active swell region, is likely to affect wave patterns and sand movement. Therefore it should undergo the most rigorous modelling and testing before any work is carried out. Yet artificial reefs for diving - created, in this instance, by blowing up 4000 tonnes of scrap metal - are being sold as a boon for the environment and locals with minimal testing of potential side-affects.
Speaking to the ABC Ian Kiernan, Clean Up Australia founder and chairman, said that sunken ships can actually benefit the environment. "Scuttling of ships has been done before and in a lot of instances it's benefited the environment through the creation of artificial reefs," he said.
So artificial reefs are actually good for the environment...?
It appears that the difference is what it is being used for. Perhaps also skewing the debate is that the Avoca Beach artificial reef is a ship that once served in the Australian Navy. The organisers maybe thinking that locals would've be thankful to have a venerated vessel sunk in their waters? An appeal to their sense of patriotism.
For mine, it is not so much a piece of maritime history but a 150 metre long, 4000 tonne supply of a finite resource. There are ship graveyards in south-east Asia where decommissioned ships are torn apart plate by plate for the metal they contain. The economy of whole towns reliant upon the supply. And yet we are blowing one up to make an underwater Jungle Jim set for a few divers to play on.
Postscript: Sell and Parker, scrap metal merchants at Banksmeadow in Sydney, will fork out $1 000 000 plus for a 4000 tonne ship. Gotta be delivered in small parts though...
Comments
Towed a bit further in, tweaked just so and the Avoca crew could be onto something. Starboard Rights in a southerly swell and heave to Port Lefts when from the north.
What are you complaining about?
D4?
at a glance, I'd say the dimensional difference between a bunch of sandbags verses a complex object, made of the key mineral that is limiting in surface waters (that's right ladies and gentlemen - the wonderful element Iron - Fe), is the key difference. One provides a multitude of habitat, structure and even "ocean fertilizer" for marine life, while the other provides a dubious chance of a wave for surf crazed city dwellers... so I guess one approach is about giving and the other about taking...
What sort of twisted talk is this?
A Titanic act of littering is actually considered 'giving'. Logic available only to PR agents and lobbyists.
Heals, what an ignorant comment! Jimmy-Dell has more than a valid point.
Ian Kiernan is right, there are many scientific studies published in the literature highlighting the positive effects that artificial reef structures can have on local productivity. Sure, that is not the primary goal of the proponents, but to say it is 'twisted talk' seems a little short sighted.
It wont take long for the ship to be completely fouled by epifauna, and become a suitable habitat for many reef dwelling species. With the constant degradation of marine habitat, and the ever increasing pressure on commercially important marine species, sinking this ship not is necessarily an environmental negative.
I assume there is potential for pollution through leaching of toxins from the materials of the ship, but one would hope this is something that has been considered and mitigated by the authorities involved? Even still,it would be a blip on the radar compared to the effluent and other toxins we pump into the ocean daily.
As for the effects it would have on physical coastal dynamics, e.g. beach erosion, I don't really know. In the scheme of things, I'm guessing it is probably a lot less destructive than any break wall or marina built on the Australian coast line?
Stu has a good point about the economic benefits a ship like this could have to a developing country - maybe a more worthy cause? But 'Titanic act of littering' - Heals, I think it is you displaying the PR and lobbyist logic with that piece of sensationalism!!!
G7?
Haha. You hit my carrier Herman!
Humpty,
Perhaps there was a bit of license assumed to string out a seafaring pun. So 'Titanic' it might not be but an awfully crude way to dispose of something it is. And this 'one is giving, one is taking' point. Why is creating an artificial reef for surfing 'taking away'?
Try as I might I really don't understand that point.
you can google hmas adelaide, and it will tell you all about the preparation and cleaning done before scuttling.
I think that turning one of these into an artificial surf reef would have to better than sandbags. I have seen photos of nice peeling barrels along the side of shipwrecks
We would love one of those down here, in the land of the 2 ft closeout
try researching previous scuttlings of de comissioned ships and submarines on the Australian coastline.
being apart of the defence force myself in the diving industry I have learnt much of the work and thought put into the process.
It doesnt take long and, alas, it can now be done over the internet.
HMAS BRISBANE in SE Queensland. Or the more recent HMAS CANBERRA in Victoria, or several of the Otway Class Submarines.
If you type in any of these, or the ADELAIDE that was previously mentioned into GOOGLE IMAGES you will be quite surprised to see the effects they have in a maritime environment.
The metals are cleaned and stripped of layers before being tested for corrosion levels, which is even before being considered for scuttling. It takes years for a ship to be scuttled.
They also create great dive sites and boost the tourism industry.
Go for a dive on one. Then jump back on here and tell me it wasnt beautiful and it IS bad for the ecosystem.
Much a do about nothing really.
4000 tonnes = the average weight of people in the water up and down the coast.....pissing,taking plastic bags to the beach,butting out ciggies, etc etc etc. Sink it create life and get on with another article Stu boy.
Why sink it in Sydney? The visibility will be mediocre at the best of times, especially at 30m.
I have studied coastal engineering and an object 1.8km from the coast and in 30m of water is nowhere near the near-shore zone - as claimed by Stuart. Depending on the composition of ocean bottom substrate at the sinking point, there is a possibility the ship may have a minor (read: MINOR) influence on sand flow. I'm not familiar with the area but I imagine there are many man-made structures on the shore itself? Groynes, jettys, etc? If so this negates the arguement that the ship will degrade/interrupt the natural equilibrium of sand dynamics, as this has been done years ago (before the notion was even concieved).
I think $1m worth of steel (minus dismantling costs) is a small price to pay, given the possible benefits through tourism, fishing and the rest. Given the efforts made to clean the vessel it would also seem a benefit to the environment.
Good on you Sanpedro, as was stated its all a do about nothing compared to other issues that affect the ocean.
Cheers sanpedro. With regards to man-made structures on the beach -- there are none. The only one is the rockpool at the south end which was constructed around the middle of last century (I think) by some SLSC folk. Other than that, it's just a standard beach which happens to have a unique sand deposit all the way out to where the boat is to be sunk. One point is that the lake in the middle of the beach gets discharged a few times a year (http://www.flickr.com/photos/dylanfm/3613333693/in/set-72157604050637957/). All the sand and crap that comes out from there will be sent straight out towards the boat. Not only do I wonder what effect the boat would have on the beach's unique sand deposit, but I wonder what could happen over time as sand possibly accumulates around the boat from the lake being opened.
The boat's location has been chosen because of the sand deposit, it's 30m deep which is great for all levels of diver (or so I've been told) and it's just around the corner from Terrigal Haven with it's dive shop, accommodation and boat access. A boat of its height sitting in 30m of water means that (I think) its top would be about 9m beneath the surface. Would this affect a solid 2m+ groundswell as it comes into the beach and point?
they should drop it in the carpark or on the beach.
just like they drop their rubbish down at that beach.
actually, put it across avoca drive and trap the morons in. ha ha
they should drop it in the carpark or on the beach.
just like they drop their rubbish down at that beach.
actually, put it across avoca drive and trap the morons in. ha ha
they should drop it in the carpark or on the beach.
just like they drop their rubbish down at that beach.
actually, put it across avoca drive and trap the morons in. ha ha
Good on ya hihi, obviously not a local of Avoca, lets dump it in your front yard and see how you like it, rather it there than ruining our super bank availability and prospects. And further more the ship was not cleaned properly as can be seen on the noship.com.au website
Yawn.
Generally speaking, a wave requires a depth of less than or equal to 0.75 its crest height to break. Hence a 2m groundswell would require a depth of less than 1.5m to break.
Assuming the depth to the ship will be 9m, then the wave height would have to be 12m!
So unfortunately it is unlikely that the wreck will have any effect on wave height.
The NSW Govt reports say that swells of 5M or more "will feel the effects of the submerged vessel", mind you the report comes from a mining company, so take it with a grain of salt. They haven't modelled extreme wave conditions, and therefore the effect the vessel will have on refracting the storm swells and impacting on beach sand erosion during storms. The wave condition data they used was "representative of the average" because the had 'computational inefficiencies", inefficiencies alright, get a new computer and do the job properly I say.
There are also concerns about the artificial reef attracting sharks, and therefore more shark attacks. A shark attack in January, 2010 at Boings off Ocean Grove is an example, there is a warship artificial reef there made when they scuttled ex-HMAS Canberra. The surfer was an eye surgeon and had to have surgery on his hand after the attack. There was a kite-surfer killed by shark attack in Florida in Feb 2010, the nearby artificial reef is called "Bull Shark Barge" because the bull sharks like to hang around for the easy feeding. The sad thing is tht NSW Govt. haven't even commented on any of this, all they seem to think about is the divers and the dollars.