Aramoana Wrecks - A Changing Environment

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Aramoana Wrecks - A Changing Environment

A few Dive Otago Club members have recently dived the legendary Mokoia and I believe it would be prudent to pass on their observations of the sunken hulk itself. To catch our readers up to speed, the Aramoana Mole is the final resting place of several 100 metre long Iron and Wooden beamed steamships, each with a history that is steeped in the World Wars as troop ships, and were also used as passenger transport ships through the Pacific. The wrecks, when no longer required, were scuttled on the harbour side of Mole and now serve a great and necessary ‘Duality’. The first is way they hinder the effects of most erosion from the Mole structure itself by acting as giant wave energy absorbers, and they also serve as a fantastic training site for our up and coming SCUBA enthusiasts based in our local area.

b2ap3_thumbnail_aramoana_mole.jpgIt's important to note we as Scuba divers and Dunedinites have an invested interest in the need for the Mole to stay intact as it directs a 'tidal jet' with the incoming and outgoing tides. This creates water deep enough for Cruise Ships and large Container ships to sail on into Port Chalmers, which is a definite boon to the city’s economy. Also without this structure our harbour would be a lot shallower, as silt and sediment would be deposited in drastically different areas. This would definitely affect where we could potentially dive inside the harbour.

At Dive Otago we have been talking about the wrecks degradation in the staff meetings over the last year, but within the last month we have had constant major storms blowing through that have created some large swells, with the maximum recorded height an estimated 5 metre swell that hounded Aramoana Mole for at least 4 days. Its a good idea to inform you, of course we often get strong winds around our coast here, (we live in the rugged south after all) but it’s the direction these swells in the last month have been rolling in that makes all the difference. North Easterlies regularly generate a swell that makes entry and exits fairly difficult if diving from shore but these are usually weaker systems in terms of wind. This is the direction that we usually look out for if planning a dive at this site, there’s a handy little webcam on the Port Otago website that faces the Mole to see whether conditions are acceptable. A line of whitewater could indicate a swell, but it’s also useful to gauge the colour of the water which translates to estimated visibility, and see how windy it is out there before driving for the 40 minutes it takes to arrive at the site.

Within the last month it’s the South Westerly storms that have been making the southern coast look a vast expanse of foamy cappuccino-esque water, and these have some real wind energy behind them . Taiaroa Head Lighthouse has wind instrumentation that has recently been measuring wind speeds at almost 150 kilometres per hour (off the charts , past 70 knots) and these high winds have been generating unbelievable swells that have been completely swamping White Island found off the coast at St Clair (which is a popular beach destination for the benefit of our out of town friends). Wave energy doesn’t just travel in straight lines either, it’s as liquid and fluid as the medium it’s travelling in. It was these hectic South Westerly swells that were wrapping around the Peninsula and crashing up against the Mole, and in some sets right over the top of the rocky structure which is truly an awesome (in all senses of the word) sight to behold.

That constant amount of weathering could have changed the look of the wrecks dramatically, and at the very least could have caused instability in overhanging portions of the wrecks.

Even in my time at Dive Otago as an instructor I have seen significant changes to the Paloona wreck which used to have a fairly intact stern Cabin, complete with a small room to penetrate with a ladder to follow up out the roof of it. After a similar storm system ravaged the Mole several years ago this cabin had collapsed - A wreckage of iron that had crumpled in upon itself where surrounding surfaces had been stripped clean of the sponge growth that had been attached for decades. Recently divers have reported that the undercutting found at the bow of the Mokoia has become very noticeable, and the energy enacted upon this particular feature has uncovered some interesting new parts of the wreckage that was previously buried in several metres of sand and shell.

As divers we need to be aware that Wreck diving, as spectacular as it can be, has extra concerns in terms of planning dives, and risk management. 

Key Points to remember:

  • Hazards should definitely be considered and discussed within your buddy team so as not to put yourselves at any unnecessary risk.
  • The energy spent by the savage swells in the last month may have caused some parts of our local wrecks to become unstable so optimal dive behaviours such as neutral buoyancy, and to staying close to your dive buddy should always be adhered to.
  • Please don’t enter any portion of the wrecks without significant training and experience. The PADI Wreck Diver Specialty Course teaches safety considerations for navigating and exploring wrecks, surveying and mapping a wreck, using penetration lines and reels to guide exploration, Techniques to avoid kicking up silt or disturbing the wreck and its inhabitants.
  • Check the weather for the diving day but also the weather in the preceeding days
  • Read the dive site information on our website for weather recomendations and hazards

Please don’t hesitate to contact Dive Otago if you note any areas of instability around our local sunken treasures.



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