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Trouble in Paradise May 2, 2016

Posted by Chris Sullivan in Dive Log, Equipment.
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The morning dive was a good one. The Spiegel Grove was in fine form, although visibility was less than I’ve seen it previously. I was diving with Joe, who was on a rebreather. Rob had a low battery on his unit and wisely decided to give the day a miss, although I missed having him on the dive. We did a loop around the superstructure and then went into the 95′ deck where there is a mess hall and a workshop with a large lathe and other tools. Unfortunately Joe had a bad cell (giving me ammunition for ongoing but lighthearted arguments on the merits of rebreathers vs. open-circuit technical diving) and we ended the dive earlier than planned with only 4 minutes of deco needed on my part. Joe sat out the second dive so I went in with the recreational divers for my second dive without carrying any deco gas and finished the dive taking Jody for a tour of the same deck as the first dive. Because of a slightly shortened surface interval and a second deep dive I ended up with about 10 minutes of deco, with no 50 mix available to speed it up.

I went up the line at 30 fpm, the maximum recommended amount and started doing my stops. The 30′ stop cleared almost as soon as I got there, and the 20 minute stop was fairly short and I was at 10′ before Jody caught up. I’d seen him hanging below me and found out later he was wondering where I was, but eventually realized that I was above him. Because we were now the last divers in the water, I hurried things up by finishing my deco while swimming to the back of the boat. I’ve often done this just for fun but this time it saved 2 or 3 minutes for both the other divers and crew.

On the downside, I went into the Ocean Divers shop to buy an air fill for my doubles. The woman behind the counter made eye contact and I asked for a fill, at which point she seemed peeved and told me she had to finish some form or other for someone else. I told her I didn’t mind waiting and in a few minutes I was charged $8.60 and given a ticket to take downstairs. I talked to the guy in the air fill station who was helpful enough and gave him my ticket. No claim ticket was given to me, which I thought strange as they had no way of telling it was my tank. He asked me if it would be OK if I picked them up in the morning as he was busy with fills for the charter operation. That was fair enough and I agreed. They opened at 7 so I had time to swing by and grab the tanks on the way to a different operator for the next day’s dive. One difference between Ocean Divers and all the other dive operators in Key Largo is that the others will fill your tanks for free, but there, if you want to bring your own, you pay for the fill.

The next morning we were there at about 7:40 to pick up the tank. The guy I talked to the day before wasn’t there, and the fill station was being staffed by the same person who sold me the fill the day before. She told me that they didn’t get around to filling the tank. When I pointed out that I’d been promised it would be filled by morning, she told me that their policy was 24 hour turnaround. So bizarrely, I had to point out that irrespective of the policy, which had never been revealed to me, a promise is a promise, and the tank should have been filled. She offered to fill the tank right then, so despite this making us late for the boat I had no choice but to let her do it.

She first hooked a Nitrox hose to it, although I’d asked and paid for air. When she was called on this she said that the tank was labelled Nitrox and must be filled with Nitrox, not air. I probably should have taken my tank right there and then but I needed the fill. In rare circumstances her statement is true, when the air station is not O2 clean, but her statement reflected a misunderstanding of the nature of the problem, and certainly shouldn’t be the case at a Nitrox facility. Next she puts two yoke inserts in my DIN valves and hooks two fill hoses to the doubles. At that point I went upstairs for a moment to see if they were a PADI facility (which they are), because we were wondering as instructors whether we were responsible for reporting such faults. We concluded we weren’t. Then while we were talking about it we heard the familiar sound of purging, although these were both repeated and extended blasts of air, not a short single purge as you’d expect.

Mine was the only tank being filled so clearly something else was wrong. Looking in, I noticed she tried to tighten the valve on the left tank in the open position, just as we’d guessed. I pointed this out to her, and while closing it, she told us “the yoke is still not going to come off”. I told her she’d have to purge it first and she snapped “I know what I’m doing”. So I said that we were both certified gas blenders and we were just trying to help – a statement met by silence. Sure enough, with the valve closed and the whip purged, the yoke came right off. I wished her a nice day as we sped out of there, unlikely to return in the foreseeable future.

Mine was not the only case of rudeness, incompetence and egotism (a dangerous combination in diving) at this operation. The other disappointments will be written up by others and I will provide links to them in this blog. I’ve been to other operations on Key Largo that weren’t familiar with technical diving. None of those tried to fake knowledge they didn’t possess. Some might be characterized them as primarily suited for recreational divers so I don’t fault them for not knowing much about technical diving, as long as they don’t pretend to. Faking competence will ultimately lead to something unfortunate, so we won’t be coming back. Some of the other operators told us there has been a lot of staff of staff turnover there, not all of it voluntary.

Fortunately, it was my one and only dive scheduled with them that week.

On the Road Again April 23, 2016

Posted by Chris Sullivan in Shipwrecks.
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So I’m on the way to Key Largo once again to dive the big wrecks. I think this is my fifth trip. So far I’ve not tired of the big underwater playground, especially the Spiegel Grove, and because I missed last year’s trip due to work it should be even more fun.

Lately in my blogging activities I’ve taken to using taking my titles from songs – so thank you Canned Heat. Not that this post has anything to do with the lyrics of the song, thankfully.

At this moment I’m waiting at YYZ (another song title) for my flight which leaves in 75 minutes. I arrived in plenty of time and for the first time in a long time all the queues were short. It was also the first time I had my boarding pass on my phone, and along with being able to get into business pass class using some of my frequent flyer miles accumulated years ago, made the airport experience almost pleasant. Let’s hope my bag arrives safely.

My regular dive buddy Rob is down there already with dive shop owner Jody taking a rebreather course. Depending on what wrecks we’re diving and what we plan to do on them, especially in the overhead environment, we’ll have to figure out how we can support each other as a dive team with a combination of open circuit and rebreather divers working together. I’m especially interested in bail-out as I understand that will be a limiting factor, and while I will be carrying lots of air and nitrox, they won’t.

I’m looking forward to hearing all about their experience. Off to the gate!

Back in the Pool February 9, 2013

Posted by Chris Sullivan in Dive Log, Training.
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It’s been a while, maybe almost a year, since I did any pool training. I could have done some of the small things a bit better, but overall it went great and we were pleased. The students were all great and none had any undue anxiety.

Maybe there’s more instructing in the cards for me this year. For once I feel like doing it again. Or maybe it was just the energizing effect of the Nitrox I was breathing (although those effects are not proven, of course).

We had 10 students, two instructors, 3 divemasters, and 3 divemasters in training. Made it easy, even though the DMiTs were doing some of their own exercises.

Florida Keys 2011 – Vandenberg September 11, 2012

Posted by Chris Sullivan in Dive Log, Technical Diving.
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This is a continuation of the trip I took in April 2011 to dive in the Florida Keys, and I’d written most of this then but decided to finish it now. Like many bloggers the urge comes and goes. I’ve left this alone for quite a while. I left off with a dive on the Spiegel Grove, but Matt and I chartered that separately, which was great because we ended up diving the wreck 3 times during the trip.

The first official dive of the trip was on the Vandenberg off Key West. We used a different dive shop, Sub Tropic this time and they were more conveniently located for parking than the previous year’s operator and a very short distance to the dive boat. The dive boat itself was reasonably well suited for those of us diving doubles.

It was a fairly rough ride out to the wreck and several divers were sick, although fortunately I wasn’t one of them. When we got there, Matt and I agreed that we would run a similar profile using our computer maxing out at either 1 hour bottom time or 30 minutes deco time, using EAN50 as our deco gas and air as our back gas. This turned out to be our standard profile for the remainder of the week, sometimes modified slightly to accommodate the various depths.

The wreck is a lot of fun where you get to swim around the big satellite dishes (and even through the hole in the focal point of one of them) as well (assuming you’re trained and equipped) lots of easy penetrations through the hallways.

The staff were among the most helpful I’ve ever seen and well-deserved the tips we gave them. The dive shop has now closed, though, but a different one has taken it over.

One thing I’ll never forget is on the ride back from the wreck we passed a Naval vessel moored near the residences for married sailors. One guy on the boat who lived there was a chief nurse who had done some rotations through Kandahar, Afghanistan, describing it as “the worst place on earth”. It made an impression.

Another Apeks Quantum Failure September 9, 2012

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My replacement Apeks Quantum failed less than a year after I received it. It’s great that I get a new one but it costs about $60 in shipping and handling each time so it’s getting to be pretty irritating. This time, it decided to start eating batteries. I noticed at the beginning of summer it needed a new battery even though it was only about 6 months old. Then again on last weekend’s dive it was too weak to dive it. I happened to have a brand new replacement with me and used it on the next day’s dive on the Oconto, but on the surface interval it was obviously dying again so I didn’t use it on the Kinghorn later than day and took it to Divetech where they said it could be replaced for another $60.

I think when I get the replacement I’ll sell it to someone who doesn’t read this blog and maybe even spring for the new Shearwater Petrel. That would give me two functionally identical computers and I would no longer need to carry decompression tables.

Apparently the Quantum is made by Seiko, and is also rebranded under several other manufacturers’ names including Dive-Rite, although though don’t seem to carry it any more but have a 3-gas model that looks similar. The Tusa Hunter looks identical, but the Cressi Archimede II is a bit more stylish but recognizably the same design. Cressi always seems to be more stylish if you’re into that –  I’m not – and their motto is “Scuba Diving in Style”.

I’ve reset more bent Quantums (or equivalents) than I can count, usually because the diver using it as a backup computer didn’t figure out how to switch to the deco gas. That happened to me once too. The trick is to hold the left button down for longer than you think is necessary. If you don’t hold it down long enough, it will switch back to your back gas.

The other Quantum trick is that after a reset it goes into metric. If you dive in Imperial units you need to go to the DIVE/GAGE screen and hold the left and right buttons down for 5 or more seconds.

Recreational Diving with a Shearwater Predator March 7, 2011

Posted by Chris Sullivan in Equipment, Technical Diving.
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My second Apeks Quantum developed a problem last summer. The first one just died, but this one has developed the common problem (that my friends have seen) which is that the depth gauge becomes unreliable. Mine will suddenly jump to 10 feet shallower than I am, beeping mightily about the astronomical ascent rate. So while I’d normally take the Quantum on a trip where the water is warm and clear, with purely recreational dives, I elected to take my tech diving computer, a Shearwater Predator, instead.

The Predator is a great dive computer. Mine used to be a Shearwater Pursuit and was upgraded once the Predator was introduced. The main differences between the two are the OLED colour display (vs. LCD monochrome) and the Bluetooth communications to the (free!) logging program (vs. Infrared). Both features make a big difference to the operation of the computer, especially the nice bright OLED display on someone whose close-up vision isn’t quite as good as it used to be due to Presbyopia.

Predator’s have technical diving features like multiple mixed gases (5 gases for the open circuit version, 5 more for the close-circuit version), flexibility for decompression schedules, underwater gas switches and changes, etc. It lacks features that recreational computers have, especially the audible alerts and the safety stop counter. I don’t mind missing the audible alerts. I’m good at scanning my computer and other gear. Also, I like to guess what I’m going to see before I look at the computer and my air supply, so I develop a good mental picture of my situation.

I use the Predator with a conservative decompression algorithm (GF 30/85, which is actually the default).  The Quantum, at least for the NDL calculation, is less conservative and my diving buddies figure it’s around GF 88/88). The tough guys at in the dive club who use Cochran Computers have them set to about 100/100, by the looks of it. The 30/85 setting means that it will go into mandatory deco stops sooner than most of its recreational counterparts. So unlike the rules that new divers are given, if you use a computer like this you either have to abide by a very short NDL or accept the deco stops.

It’s probably no surprise that I usually do the latter. In the 18 dives I logged in Cozumel I didn’t go past 6 minutes total decompression obligation. Most of the time it was 2-3 minutes, sometimes nothing. It is my belief that a 3 minute 10′ deco stop with a conservative algorithm is more or less equivalent to a safety stop. If miss, the chances of DCS are greater but that’s also true if you miss the safety stop. So in effect, I’m just getting the additional discipline of a safety stop that my computer calls mandatory. Once I’m done the stop(s), I’ll stay a while longer to get some additional safety margin or surface – slowly of course.

Getting well into deco is an entirely different matter. 5 minutes is about all I’ll do with recreational equipment. If I have to escape to the surface I’m probably going to be OK, which is as much as you can say for missing the safety stop on a less conservative computer. Any further pushing of the limits means carrying additional redundancy to make sure that I have the means to complete the decompression under all foreseeable circumstances. That’s why we have technical diving training.

Disclaimer: This is what I do. You need to understand all the facts and risks to make your own decisions about what level of risk is acceptable to you. I certify that this level of risk is acceptable to me at the time of writing, and that’s all.

Cozumel 2011 Day 4 – Cantarell Reef March 2, 2011

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Today were the last dives with Joe and Grunt, and I’d agreed to take a taxi ($16 for gringos) from the Occidental Grand Hotel to the Marina (La Caleta) so that we could dive the reefs north of San Miguel. The first of these was Cantarell Reef, which on my map is called “Eagle Ray Reef”. When I dove it two years ago there were tons of them, but you never know whether they’ll show up or not, and this time they didn’t.

Blue XT Sea’s owner, Christi Courtney, also showed up for the dive, as she’d known Joe and Grunt on-line for several years but never met them. So there were 6 of us the on the dive, including our guide Pedro, and we dropped down into the current, sometimes quite strong, sometimes almost non-existent.  All of us from time to time grabbed a handy Sponge to keep the group together. Some divers view this practice dimly as it is interfering with the marine life, but until I find out differently I believe there is little or no damage done to a big Sponge if it is held gently. It might be worth looking inside the Sponge before grabbing it, though, as you never know what might be in there!

Lion Fish in Sponge

The picture above was actually from San Juan Reef about an hour later, but it fits better in the story here… At one point, one of the divers, Joe I think, was hanging on to a sponge and noticed that he was inches away from a Scorpion Fish. These remarkable creatures are so well camouflaged I bet many people wouldn’t notice it in this picture unless told it was there.

Scorpionfish at Cantarell

Again we saw Juvenile Spotted Drums but the pictures aren’t worth posting here. Once more the shutter lag on my camera made it difficult to frame them well.

I hit a max of 108’ on the dive and the majority of the dive was fairly deep, so after 36 minutes bottom time I had 6 minutes of deco at 10’ on my computer (the 20’ stop cleared well before I got there). No one else went into deco because they were all diving Nitrox – Jackie because she always did, while Joe and Grunt decided to because they were flying the next day.

Enriched Air Nitrox Formulas February 28, 2011

Posted by Chris Sullivan in Technical Diving, Training.
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Formulas for Nitrox are used for several purposes:

  1. Calculating the Equivalent Air Depth (EAD) to allow the use of standard Air tables to calculated no decompression limits, repetitive groups, or decompression schedules.
  2. Calculating the best or optimum mix for a given depth
  3. Calculating the maximum or contingency depth for a given mix to minimize risk of CNS Oxygen Toxicity
  4. Calculating the oxygen exposure for managing Pulmonary Oxygen Toxicity
  5. There are also formulas for partial pressure filling of tanks, which determine how much Oxygen needs to be put in before topping up with air. A more difficult problem is how much Nitrox to drain from a tank before topping off with air in order to reduce the fraction of O2 in the mix.

In basic Nitrox training we’re given the formulas for 1-3, and a table to manage 4 in recreational diving situations. The PADI table uses the NOAA or “CNS” clock only, with no surface interval credit. Surface interval credit makes sense in technical diving when we’re managing pulmonary toxicity using the Repex method, but when using one table to manage both I’m not convinced that it would be wise to apply it.

Even in basic training, I usually like to point out why the formulas work, instead of using rote learning.  I first starting doing this when I took the course myself in the Turks and Caicos in 2005, and found that the understand helps me both remember the formulas (which I’ve never been good at) and to catch errors in my calculations.

Except in case 5, all of the formulas relate to the pressure of Nitrogen or Oxygen in Absolute Atmospheres. Everything that in Imperial divides, multiplies, adds or subtracts 33 (or 34 in fresh water) is converting between gauge and absolute atmospheres, and the formulas themselves are much easier to remember in ATA than in ATG.

MOD Memory Aid September 17, 2010

Posted by Chris Sullivan in Technical Diving, Training.
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Maximum Operating Depth and Contingency Operating Depths for Nitrox diving are defined (by most) as the depths you reach PP02 of 1.4 and 1.6 respectively, indicating the recommended safe limits for continuous Oxygen exposure during the working and deco portion of a dive.

When I was teaching a Tec 40 class we were discuss MODs and other depth and pressure related calculations and I was using the formulas to explain the principles behind the math, the instructor mentioned Daltons’ Diamond, which I had to confess not remembering. It looks like this:

      /\
     /  \
    /PPO2\
   /______\
  /    |   \
 /Depth| FO2\
/______|_____\

It says that Depth*FO2=PP02, PPO2/Depth=Fo2, and PP02/FO2=Depth. The trick is that depth is in Absolute Atmospheres, so you need to divide FSW (feet of sea water) by 33, FFW (feet of fresh water) by 34, MFW (metres of fresh water) by 10, etc, then add 1. For instance, 50% mix at 33 feet is FO2=.5, Depth=2, so PP02=1 (and safe).

The memory aid is simple for people who used computers, and useless for those who do not. The triangle is made up of the first initials PDF (PPO2, Depth and FO2), which is the file format used by Adobe Acrobat.  Once I noticed it I never forgot it, and neither do my computer-using students.

Tec 40 Graduation Dive June 29, 2010

Posted by Chris Sullivan in Dive Log, Shipwrecks, Technical Diving, Training.
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Rather than end up at our usual mud hole, on June 13th 2010, the Tec 40 students, assistants and instructor met at Caiger’s Resort along the mighty St. Lawrence River to knock off the class’ first (authorized) decompression dive. With 3 students, an instructor and 2 assistants, we had an easy time of it, with the students forming a team, but also being buddied up with a certified pro to both harry them and be around for emergencies.

The location was Ivy Lea Ontario, just a little upriver from the Thousand Islands bridge. I’d been there once before, and having enjoyed it the first time, was looking forward to doing it again. The dive consists of dropping into the river about 1/2 way along Ash Island, then drifting to a wreck known as the Ash Island Barge.

Once we’d entered the water, gathered together and done our bubble checks, we dropped over the wall to our planned depth of 125′. Actually Dave went a bit deeper to see if the students would follow him. They did, but soon caught themselves and got established at the proper depth. About 1/2 way through the drift we stopped and went through some drills, then continued on to the barge.

By the time we got there, we were almost out of time, so a couple more quick procedures and we headed up for our deco. Each student performed a gas switch on the way up to their decompression stops and soon thereafter our new graduates were floating on the surface where the boat was waiting for us.

Graduates waiting to be picked up

Because I need to log some 130+ deco dives to qualify for Tec Instruction, I followed Dave down to 132′, and used EAN50 for staged decompression. Water temperature was 15C (58F) on the bottom. We’re looking forward to diving the St. Lawrence again with some new students on Saturday. It should be even warmer.