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CCR, O2 Consumption & Exercise October 31, 2016

Posted by Chris Sullivan in CCR, Fitness and Nutrition, Technical Diving.
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With a little less than 12 hours diving a CCR, I’m now venturing to comment on a technical aspect of the experience which dawned on me recently. Surely I’m not the first to think about a CCR in this way, but I’ve not come across this analysis previously and wanted to record my thoughts about it here.

The more I dive the more I concern myself with staying fit, as I’m not getting any younger, and that gets me thinking about both capacity to expend energy and calorie consumption. Rebreather training tells me that when things are going right, bubbles are only released upon ascent, which is just the excess volume from the loop as the gas expands with the decreased ambient pressure. Other than this, all the Oxygen consumed during the dive is metabolized by the diver.

Fitness evaluations are frequently done by measuring inspired Oxygen, and except for what is released on ascent the CCR will measure that based the change in O2 tank pressure. I found this article that directly relates calories burned to O2 consumption and also relates O2 consumption to METS (metabolic units, a measurement of energy used in exercise) and body weight.

I’ll give an example, which for simplicity I’ll use metric units. My CCR has a 2 litre tank, which can be filled to 230 bar. So its capacity is 460 litres. Say I do a 60 minute dive and the pressure in the tank goes from 230 bar to 180 bar, a consumption of 100 litres of Oxygen. Ignoring the bubbles on ascent, I’ve burned 500 calories (100 litres at 5 calories/litre).

I weigh 72.3 Kg right now. 1 MET energy output uses 3.5 ml of O2 per kg of body weight per minute of activity, so if we know our O2 consumption in litres the average number of METs used in the dive will be (litres x 1000) / (body weight x minutes x 3.5). So if it were me doing this dive my average energy expended would have been about 6.6 METs, which is a little less than this source gives for slow cross-country skiing.

Coincidentally, according to the calculator on this site, my current treadmill regime of 3.5 MPH at 6% slope also requires 6.6 METs (BTW tomorrow I increase to 7% slope or 7.1 METs).

Conclusions

So I’m inspired (pardon the pun) to think that this yet another great feature CCR diving. I can now, with reasonable accuracy, determine the calorie expenditure on a dive, and replenish accordingly. I also know how hard I’ve been working on the dive and train to that level.

Regarding the bubbles on ascent, there’s probably reasonable way to estimate how much O2 is going overboard. Fodder for a future post, no doubt.

Exploring the Eagle May 16, 2016

Posted by Chris Sullivan in Dive Log, Shipwrecks, Technical Diving.
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Once again with Conch Republic, we headed off to the Eagle for the second and final time of the trip (the previous time we went there after deciding not to dive the Duane due to current). Joe and Rob were on their rebreathers with me on my doubles. Descent was uneventful and as usual I deposited my deco tank in a crevice on the wreck near the stern descent line.

Joe led the dive. We headed for the top of the superstructure on the stern, entering the wreck on the starboard side which was near the ocean bottom. We entered a non-descript room and Joe headed through a doorway, but unfortunately left a fair amount of silt behind. Unwilling to enter in zero visibility, I waited, illuminating the doorway with my dive light in case Joe was having any difficulty finding his way out. Within a minute he reappeared and we headed in a different direction exiting the forward end of the superstructure.

There we saw a Goliath Grouper just inside the wreck. There were some divers about 10′ above us and I tried to get their attention so they could take a look at him, but none looked in our direction. We then started wondering where Rob had gotten to so we went back to where we entered the superstructure then back to the line to look for him. We saw him 30′ or so above us signalling “OK” with his dive light, finding out later that he lost most of his diluent supply getting through the first door and decided to bail out. I’m glad we saw him and didn’t have to search the inside the of the wreck.

Atlantic Goliath Grouper

                                            It was bigger than this one

After doing a lap around the bow section, we returned to the stern and slid back in near the prop. You have to get low to the bottom to do this, and the interior is prone to silt so good wreck penetration skills are needed. 2 years ago we were swimming through the same spot and it started to silt up, prompting me to quickly exit the way I went in. This time was much better and we went sideways through a hatch (or maybe just a hole) into the very bottom of the ship, where there were reassuringly several large exits, although not much else to see. After this we went back to the line and ascended – and as usual Joe was finished his deco about 3x quicker than me.

Once more to the Spiegel Grove May 13, 2016

Posted by Chris Sullivan in Dive Log, Shipwrecks, Technical Diving.
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The last deep dive of the week was once again on the Spiegel Grove. Did I want to dive the same wreck 3 times in a week? Hell yes. I love that dive. This time four of us, Rob, Jody, Joe and me all together exploring levels 1 and 2. Level 2 is perhaps the more interesting one as it has the mess hall and the workshop, which has a grinder, planer, drill presses, lathe, hoists, workbenches and welding equipment. No-one seemed to have much trouble getting through the doors this time and we didn’t have any bailouts.

Near the end of the dive we were in the workshop when through a doorway we saw a large (no, like, really really big) Goliath Grouper hanging out. We watched him for quite a while but he eventually swam away slowly. We followed after him, descending through an oval hole and under the deck that overhangs the dry dock area. It looks from the plans like the hole once housed some kind of smokestack, but in (not 20/20) hindsight I’m a little fuzzy on which deck some things were on. The plans don’t show the stack on the workshop deck. It looks like once through the hold we swam out from under the deck on which the 3″/50mm guns used to be mounted, just before getting to the 50 ton cranes.

To be honest even though I surface with the feeling I was really getting to know the layout of the decks, in retrospect I’m not entirely sure what was on each deck, except for the mess hall and the machine shop. When I look at the plans I can’t reconcile everything with what I remember. Maybe narcosis is factor, or maybe the ship was reconfigured after the plans were drawn.

We also came upon the “Top Dog” floor mural in one of the hallways in the approximate centre of the deck, which I’d not seen before. It’s easy to overlook, being in a nondescript hallway running across the deck, and partially covered in silt.

TOP DOG - USS SPIEGEL GROVE (Floor Mural)

That was the best dive of the week, although I really like to go into the below decks again where it’s necessary to run guidelines. I’ll have to wait for my team members to get a little more time and confidence on their rebreathers before doing that again.

Day of the Eagle May 7, 2016

Posted by Chris Sullivan in Dive Log, Shipwrecks, Technical Diving.
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For dive #3, Rob was down with a cold and Joe was still waiting for his O2 sensors to arrive. Jody had arranged to do his final dive of the rebreather course with the Gary, owner of Conch Republic, so I arranged to dive with them. This time we were on the Eagle. It was a fine day (like all of them) and current was minimal when we tied off on the stern line. When we’d descended to the wreck I put my 3/4 full deco tank (50% 02 in a 45 cubic foot steel tank) on the wreck right next to line. I recalled when diving the same wreck a few years before with Matt we’d initially staged on the bottom and as we swam away I realized that 115′ wasn’t the best depth for them, so we’d gone back and put them near the line and 30′ or so higher – saving us from descending again near the end of the dive.

Mindful of their near optimal O2 mix and effective gas capacity, I stayed about 10′ above them for most of the dive. I followed behind most of the time with Gary leading the way. We went inside the superstructure on the stern section for a bit but it was difficult for Jody to maneuver easily in the sideways wreck with his new kit. We also toured bow section, separated from the stern by Hurricane Georges in 1998, going round the bow from deck to hull then through a hole about half way day back to the deck. At one point I helped Jody get through a swim through which was giving him trouble because of the position of the bail-out tank. I just lifted it and he went right through. Then, of course, I had to make a point of sailing through without any contact, just to show myself that I could in my doubles, as no-one else was watching.

By the time we got back to the stern line I had 18 minutes TTS (time to surface) so I waved goodbye and went up to my first deco stop. By the time Gary and Jody came up I was nearly finished my deco and when I was done, I went back on the air in my doubles and hung out with them near the line while they finished theirs. I only had 100 PSI of 50% Nitrox deco gas left at that point, which was about 4 minutes worth, but at least an hour of air as a contingency in case I had run short.

While I love the Spiegel Grove for its sheer scale and upright position, the Eagle is a cool dive, especially once you get to know your way around it.

Decompression Period May 3, 2016

Posted by Chris Sullivan in Dive Log, Equipment, Shipwrecks, Technical Diving.
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Dive #2 was supposed to be on the Duane. It’s not my favourite wreck down there, and I’ve often said I could dive the Spiegel Grove every day of the week, but I’d never turn down a dive on the Duane. This time, though, when the Conch Republic boat got there, the buoys marking the site were under water, meaning very strong currents were present. I’ve dived the Duane in conditions like that and we had been surprised no-one had been swept off the wreck, so discretion prevailed and we headed off to Dive the Spiegel Grove again, which, of course, I didn’t mind one bit.

There was a fairly strong current on the Spiegel Grove as well. I was feeling slightly queasy after the long ride, but when I got to the back of the boat I was asked to wait as Rob was still getting ready. I sat down and didn’t feel to good so I told the crew I’d wait in the water and went in. It took some hauling to pull myself through the current to the descent line so I used the waiting time catching my breath using the atmosphere instead of my tank. Even so I used 400psi (about 28 cubic feet) just getting down to the bottom of the line, although some of that might have been lost due to the change in temperature. Using water temp of 27 and air temp of 33 the change in pressure due to temperature would be equivalent to about 6 cubic feet.

I was with my trusty buddy Rob. He was on his new rebreather so we didn’t push too hard – doing the swim throughs on the first and second levels above the main deck – and after reading some of the APD Inspiration manual I’m sure he had plenty enough to think about. Even though we were to dive the Spiegel Grove no less than 3 times during the week, we never penetrated the wreck below the main deck, where we need to run lines, choosing to stay conservative. In previous years we’ve gone one level below the deck and I was hoping to go further this year but it was not to be.

Rob’s kit wasn’t as streamlined as his doubles because his bail-out tank was not as parallel to his body as we tend to have with our doubles, and at one point he had to extricate himself from apparently entangling some of the many hoses on his kit while going through one of the doorways on the wreck.

As usual I racked up a bunch of deco time. Rob had very little, so this dive goes to the rebreather for minimizing hang time, although marks were deducted for the hangup in the doorway. Mind you, we were entertained by a group of Barracudas which circled us on each stop and the water was warm, although it would be been more fun to spend that time on the wreck.

Conch Republic handled everything wonderfully. Their setup on the dock is easy to use with the nearby fill station (although Mark carried my doubles to the fill station that day), hoses, hangers and dunk tanks.

Return Scuba Diving Trip to Fathom Five October 1, 2008

Posted by Chris Sullivan in Dive Log.
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The only time I went diving in 1984 was in August, a few days before the maiden voyage of the Space Shuttle Discovery, when I took another trip with the dive shop to Tobermory. By this time I was the proud owner of a Volvo 240 Turbo 4-door sedan, and three of us drove up from London the evening before the dives. I’m pretty sure we camped out again in Cypress Lake.

One of the two passengers was Grant Cudmore, who was later to die on an ice-diving course at the quarry in Innerkip. Both my passengers were smokers, and having a relatively new car I wouldn’t let them smoke in the car, so we stopped a couple of times so they could have a smoke outside. The Volvo had a feature made for ski transport where the middle part of the back of the rear seat would fold down providing access to the trunk. This was perfect for beer, so that it can be kept in the trunk except for the one you’re actually drinking at the time.

Once we got to Tobermory the owner of the dive shop was incredulous that I wouldn’t let them smoke in my car but I allowed them to drink. I should point out that while it is legal for passengers to drink in the car in some US states, it is quite illegal in Ontario.

The itinerary wasn’t that much different to the year before. My buddy Jim Byrne and I dived the James C. King again, and this time I actually went through the narrow opening under the hull, the presence of which the park authorities no longer acknowledge. The water was righteously cold at 7 degrees Celsius (44F) and chilly in our wet suits. We didn’t spend a lot of time below the second thermocline. The weather was fine both days with temperatures ranging from 19 to 26 degrees Celsius.

We got our air fills from G+S Watersports, which is still in operation. The owner at the time was an old woman, who I haven’t seen in recent years. They still have curious items lying around the shop. One of them, no longer around, was a homemade Oxygen Rebreather belonging I think to the woman’s son. Some people apparently still make their own rebreathers. I still go there for air fills and I must ask them about their history next time I go.

W.L.Wetmore at Fathom Five National Marine Park

Author with W.L.Wetmore Anchor. Photo by Roger Morrison

Our other dives were the shallow wreck W.L.Wetmore, a Flowerpot Island “Cliff Dive”, the harbour wrecks Sweepstakes and “City of Grand Rapids”, and finally the Grotto once again.  The Wetmore is a nice shallow dive with a maximum depth of about 20 feet. There is a nice anchor which you can see in the picture (taken in 2007) and a large boiler to see among the scattered timbers. The warm water at the end of season is well appreciated when in a wet suit, and a bit of a break even in a dry suit.

So other than the Wetmore, it was pretty much a repeat of our previous trip.