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Dive Report 16/11/97

Meggol and Dee Why Wrecks

Diver- Jason

Perfect conditions greeted us for the first run of my 'breather on a deco dive. I'd mixed up some TMX during the week, but due to stupidity, I'd ended up with far more O2 in the mix than I wanted, and had to mix up a second cylinder on Saturday. Fortunately it was OK this time, and it analysed up at 29.5% O2 (target 30%)

This made for 50% He, 20% N2, and 30% O2, to give a PPO2 on the bottom of 1.8

Hopped on Barry's second boat, bound for the Belluburra but a vote changed the destination to the Dee Why. I wore the unit all the way out, as it's still too fragile to put down on the deck of a bouncing boat, but it was reasonably light, and no real problem.

I went on the set about 15 minutes before arriving but only for about 10 minutes. The idea was to preheat the set, and make sure that it was working as advertised. No problems, but I did find that the mask fogged up pretty badly, so next time I'll take a small water container so I can spit in the mask, and rinse it without getting up. (It's hard to rinse a FFM that's attached to a breather!)

After we picked in, I was able to climb down the ladder, and rinse the mask properly due to the very calm conditions that we were blessed with. Donned the mask and flushed through with pure O2.

We had tied up to another boat, and so there was a short surface swim over to their anchor rope. No problems, and I waited there for my buddy (first buddy dive for a long time for both of us) Paul Angwin.

Paul is another home builder, but due to work and family, his set is still in the early stages, so he was on OC for this dive.

When Paul arrived, I descended to about 6m (to compress my neoprene drysuit enough to make me negative) and did three flushthroughs to get the O2 out of the loop. As I was diving SC, my drive gas had a very high PPO2, and if I'd descended with a loop full of O2, (one bar of O2) this would have added to the 1.5 bar of O2 that would have come in with the 30% TMX to make an unhealthy bottom mix.

I descended on the TMX, with Paul following, adding gas to the loop with the auto dil add that you can see in the photos of my set. There was a hell thermocline at 24 metres, which made me think I'd made a mistake leaving the underwear at home!

Soon the Meggol appeared out of the gloom, and I settled on the bottom to get my bearings and adjust my buoyancy with the unfamiliar gear setup.

Paul looked calm and collected, and signalled we should head off the bow of the Meggol. Not a bad idea, so that's what we did.

After a short swim, we arrived at the Dee Why. I was surprised to see the state she was in. It's been about two years since I last dived her, and she'd changed a lot. The superstructure has collapsed into the hull, and one end (she's a push-me-pull-you ferry, so neither end is the "bow" or "stern") has fallen over leaving a tangle of twisted metal where the clear lines of a steam ferry had been last time. The swimthrough under her boilers and around her working gear has all filled with metal, and she's very scary looking! Even without the delicate breather on, I'd have been content with swimming around her rather than inside.

Diving on 50+% He made me realise that I'd been narced on all my previous visits to this wreck (50 metres). It seemed that the wreck had been transported to Little Coogee Bay, in about 6 metres of water! There was simply no feeling of depth.

Early on in the dive, the CO2 level built up a bit, and I started to get a bit "puffy". I suspect that sitting on a boat doesn't get the scrubber up and working the way walking from the car down to the ocean had done on the shore dives I'd been doing up till now. Still, it was no problem. I simply stopped and added a short pause at the top and bottom of each breath to give the gas some residence time and the CO2 dropped right off.

After a bit of fooling around, we made our way back to the Meggol, and swam nearly her full length on the top deck. She's been treated more kindly by age. As an oil barge, she'd lacked the grace of the nearby Dee Why, and had always been the poor relation. Now with the Dee Why disintegrating into a pile of twisted beams, the Meggol has aged quite differently. She's beginning to loose steel plates, and so her holds are beginning to open up. Looking in the hatches shows a greeny glow where there had been darkness before, and thousands of nocturnal fish, sheltering from the day.

I'd been dumping one full breath every two minutes through most of the dive, but now our time was almost up with my aladin showing 20 minutes.

I looked to Paul to signal an about face, but I found he was already making the "turn" signal.

I started to dump every minute on the way back, to raise my FO2 for the ascent. We'd been on the top deck, at about 42 metres, so I altered my planned Pylian stop from 40m to 30 (first Bhulmann stop at 24).

We got back to the anchor rope, and started up at about 6m/minute. I stopped at 30 as per the revised plan, and Paul stopped a couple of metres above me, to keep an eye on me in case I dropped off the line. I was still dumping at 1 breath/minute through this stage of the dive.

After a couple of minutes, I moved up to 27 for a minute, and then to 24 for a minute. At that point I turned off the TMX and purged the lines (to assure myself that it really was *off*) and then opened the NTX 63 cylinder. When I moved up to the 21 metre stop I did another dump, and brought some fresh 63 into the loop. (I'd cut the table for 50% used at 18m, so the program thought I was still on TMX). For the next part of the dive I was dumping every two minutes, but at 12 metres, I did a flush and then dumped a lungful and made up with O2, and then maintained the loop volume with O2.

I did the same at 9m, and then did it again about half way through the 9m stop (to assure myself that I'd not let the O2 "wander" too far).

At 6m I shut off the NTX and flushed with pure O2. At about that time Paul got out of the water, and I was only a few minutes behind, with a total runtime of 61 minutes. I missed about five minutes of my scheduled 3m stop, but I wasn't worried as I'd fudged like mad the rest of the way. I'm sure that I could have skipped the 3m altogether without any problems.

After the dive I felt **Great** and I wanted to go again! I used to feel that using O2 deco made me loose almost all the air blues, but helium in the mix made an enormous difference.

In all, I used 80 bar of TMX for the dive, including all the flushing and the deco. That's from a 5 litre cylinder, so that's 400 litres, or 14 cuft. If I'd bought the Helium from a shop, that would have been $14 worth of He and a couple of bucks for the O2, and mixing.

Because of the low pressures I'm using in the big 5 litre cylinder, I can top off the remaining gas, so the helium that's left over isn't wasted. I'd only filled to 130 bar (about 1800 psi) and had 50 bar (700 psi) left.

Doing the same dive OC would have been about 120 cuft of mix but I'd have had to take 160 cuft for some reserves. About $160 worth of He, and about 15 bucks worth of O2 and two mixing fees.

It makes it affordable, and when I change from SC to CC, it's going to be even cheaper (per dive)

The main thing that I found on this dive was how *easy* it was. I just swam around and breathed out my nose every time the bottom timer had an even number on it. The TMX was just lush... I'm never going to dive air again! I can hardly wait to do some big dives on this unit!

I'm going to have to move my tee's further back though. The hoses were giving me the screaming irrits by the end of the dive.

Cheers Jason =:)

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