TSS Currajong shipwreck
Considered the best preserved shipwreck of NSW, the 67 meter long TSS Currajong lies in 23 meters of water under the shipping channel off Bradleys Head.
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For an excellent description of the history and sinking of the ship visit Michael McFadyen's Scuba Diving website. On that website you will also find rich information for diving this, yet I felt that providing an additional description would not hurt, especially considering the danger involved in this dive and the need to plan it carefully leveraging all the available information. Updated as of October 2020, all the depths are indicated at high tide.
This dive presents a number of risks to be considered. The most obvious is the fact that it requires to swim under the shipping channel where all the traffic goes through, so under no circumstances a diver should detach from the sea bed and surface. Bring with with you a surface marker buoy (SMB) in case an emergency forces you to do so. One less obvious risk is represented by the sailing boats that without noise to announce their approach, they may cut the corners around Bradleys Head and navigate in shallow waters, where you may think to be immune from boating risks, so just stay always low on the bottom and avoid wandering around, also because there is literally nothing else to be seen in the area.
Consider that the harbour is affected by tidal currents, so best diving across the high tide time.
Worth checking on the Port Authority page that no vessels are expected to transit at Bradley Head the time of the dive.
Key is to be very familiar with compass navigation. The water can be very murky, and can literally obfuscate anything beyond the range of 2 meters.
From the legal standpoint, I don't know if divers are allowed to be there. I have tried my best browsing the Port Authority of NSW website but could not find anything specific to the case. Some dive operators organise boat dives at 1 AM, at that time there is not traffic in the harbour and the boat can stop right above the wreck (still needs to receive clearance from Port Authority). I did it in 2017, it was December and the Dive Master was wearing a personal Shark Shield without talking too much about it. Now that I learned that bull sharks have a seasonal presence pattern I would probably avoid diving the harbour in the months between November and April, at least outside the usual spots such as Chowder Bay.
The depth of the wreck is 23 (bow) to 26 m (stern), to eliminate one variable and focus on navigation I would do Nitrox for peace of mind.
Most of the air will be used for the transfer because there are 200 meters to swim each way, even in the best case scenario in which the wreck is found at first attempt. Once reached the wreck, it's a good practice to record the quantity of air consumed, so you get an idea of how much will be consumed on the way back hence how much time you can spend swimming around the wreck.
As an indication, on a 15 litres 230 bar nitrox tank, an average diver could expect these consumptions (as a guide, clearly it's subjective):
Reaching the wreck: 200 m in 8' consuming 50 bars
Bottom time on wreck: 23' consuming 80 bars
Return from the wreck: 200 m in 8' consuming 50 bars + safety residual pressure 50 bars.
The Curragion is sitting 200 m from the coast with the bow pointing towards Bradleys Head , finding it presentes the same challenges as if we were trying to hit it with a torpedo, but it's actually quite easy to find it once you know how to do it. I found contradicting coordinates across various dive sites, so I took a GPS fix at the donkey boiler halfway through the wreck and it's at -33.854794° 151.249064° WGS84 datum.
Walk down the steps to the jetty connecting the white lighthouse to the head. Get in the water and swim eastward along the coast for 35 m. To have a visual reference of where that point is, before getting dressed walk to the lighthouse and identify the point on the coast by looking at the map from Google and matching the boulders (see image below).
From there, head 120 degrees magnetic, which corresponds to 132 degrees true north. The swim to the bow is 200 metres long. One valuable information is to know your own cruise speed by measuring it against known distances. For example I know mine while carrying a camera gear is 25 m/min, so for me it would be 8 minutes to the wreck. If you don't find the wreck after T + 1 minute, it's time to stop and do a T pattern: left and right for some 30 kicks. Knowing when you are going to hit the wreck is extremely helpful to support the morale as you are swimming in the middle of nowhere, with potentially 2 m of visibility, not much sunlight filtering and thinking "are we there yet?", or "maybe I have gone to far". One way to calculate your average cruise speed is to swim underwater between two known points, like the side of a bath net. I know mine by using the GPS described in another section.
As the bottom goes deeper, if you start seeing stakes sticking 50 cm out of the ground from the depth of 8 m onwards, it means you won't miss the wreck. They are approximately every 5 meters, perfectly lined up along the 120 degrees direction. If you don't see the stakes, which means you may be off-course, one option is to swim around 8-10 meters of depth and then swim parallel to the coast looking for the stakes, once you find one just follow the next ones on 120 degrees.
After a circumnavigation of the wreck with some stops here and there to examine it, it's probably time to go back as the air would have reached 100-ish. Aim for 300 degrees, or even better just follow the stakes from the bow.
The starting point, 35 m from the jetty
The navigation to the wreck. If you find the first stakes in 8-10 m you will definitely find the wreck by following them on the 120 degrees heading