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Login failures @http://www.padimembers.com/login/ June 30, 2009

Posted by Chris Sullivan in Miscellany.
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I noticed whenever I log into the members section of the padi.com web site it always fails on the first try, and succeeds on the second. Strange thing. It may have something to do with Firefox, which I use as my main web browser.


Wreck Training in Brockville: The Gaskin June 29, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks, Technical Diving, Training.
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On July 19, 2008 8 students and 5 staff headed to Brockville for the annual wreck diving course. This course, concentrating on developing wreck penetration skills, works through 3 wrecks of progressive difficulty. The first of these, the Robert Gaskin, lies in under 70 feet of water in an area with lighter currents than some of the other wreck sites in the river. The deck is also very broken up, with lots of light and plentiful exits.

The previous Wednesday, the class had met at the shop to go through the course materials and then practice using a line and reel on land in the park across the street using the trees. Each student would lay a line between 4 or 5 trees, then reel it back in. The second time the student wore a blacked-out mask when reeling the line in so that they could do it by feel.

The students visited the wreck in buddy pairs, each pair diving it twice. Because the surface intervals were short, each had a Nitrox best mix on their backs (EAN40 on the Gaskin), to minimize Nitrogen absorption. The students were met by Andrew, who took on shuttling duties, and led to Brad and Dave, who took them through the wrecks separately (one on the port, one on the starboard) while I swam along the top to render any assistance that might be required.

One the second set of dives, once the students had laid their lines, the silt in the wreck was stirred up so that visibility would be reduced to almost nothing on the return trip. The whole process took over two hours, and by this time I was getting very low on air, and I was about to swim over to the other end of the wreck to pick up a stage bottle when Dave signalled me to take one of the students through, while he swam over the deck as safety diver. This I did, but when we  got to the other end and about to turn back, I stuck my head up through the deck and signalled Dave to hand me a tank, which he handed to me. I then clipped it on to my BC while escorting the student back the other way, feeling better that I’d be better able to help in an emergency.

Because we had a rich gas mix, and because we would ascend to around 50 feet if we were waiting for the next pair, I only needed about 5 minutes of decompression before surfacing from that long dive.

Tec “Deep” at Big Bay Point June 27, 2009

Posted by Chris Sullivan in Dive Log, Technical Diving, Training.
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It’s been a while since I wrote a retrospective, and I’m starting to run out of them as this will describe deives 218 and 219, and this blog started with dive number 241. The date was July 13th, and went out to our usual haunt of Big Bay Point at the south end of the entrance to Kempenfelt Bay in Lake Simcoe to join Brad and Dave training 3 prospective new technical divers, Andrew, Mike and Jeff.

The order of the day was to practice donning and doffing the scuba unit and shutdowns. I’ve already described my own experience in the same location with this, and is was heartening to see that the new crop of technical divers had the same difficulties as I had encountered.

The exercises started on the little speedboat which lies at a depth of 30′ along a line running east of the mailbox, near the log where we train the open water students. All started well, but once the heavy scuba units came off the buoyancy of the dry suits took hold, and those poor students found themselves clinging to  the straps to hold themselves down. To compound the difficulty, the struggling divers soon slid of the deck of the tiny boat and onto the bottom, producing thick clouds of silt to obscure their vision and knowledge of which way was up.

I stuck with Mike, who found the exercise very stressful and tiring. Once he’d struggled back into his harness we found the others had disappeared. After searching for a while we gave up and surfaced, finding that the current had taken us well east of the original location. We located the bubbles of the others and joined them for a few more minutes of fun.

Glad for the practice in my doubles, I was out of the water before noon and I headed home for lunch. It was good to get some time in before my trip to Brockville the following weekend to help with the wreck diving course, despite having not ventured below 36 feet in the hour and twenty one minutes spent underwater.

Enriched Air Diver Specialty June 24, 2009

Posted by Chris Sullivan in Training.
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I was supposed to teach an Enriched Air Diver class tonight. Unfortunately it was cancelled as the students did not commit to showing up (presumably they’ve paid and were studying all the while). I’d done a fair amount of prep for the class and will now have to wait until it is rescheduled. I had written the following in anticipation of my first real diving class.

To make the experience real, I designed a simple scenario. Last week I dived the Kinghorn and Daryaw wrecks in the St. Lawrence river which are 95′ and 90′ depth respectively. Using the air RDP table, the maximum bottom time on the Kinghorn is 20 minutes, and after a 45 minute surface interval there adjusted NDL is a mere 12 minutes with a residual nitrogen time of 13 minutes.

The eRDPml, PADI’s new calculator that is similar in function to “the Wheel”, takes advantage of 5 foot depth  increments to provide an NDL on the Kinghorn of 22 minutes, but curiously this reduces the ANDL on the Daryaw to 10 minutes. By limiting the Kinghorn to 20 minutes as with the previous paragraph, the eRDPml gives a single extra minute of bottom time to the Daryaw dive with 13 minutes total.

So what about Nitrox? There are a bunch of ways to calculate limits when diving Nitrox. There are standard RDP tables for EAN32 and EAN36. You can also use either the RDP or the eRDPml using equivalent air depth (EAD), which adjusts the depths for the calculations to one with the same partial pressure of Nitrogen as when diving with air. The EAD can be calculated with a formula or by using the EAD table, which will introduce additional rounding errors into the calculations because of the 10 foot increments.

Finally, you can use standard mixes, or use a formula to calculate the best mix for a given depth. With these dives, it gives a very modest advantage to do that. So there are a plethora of options as follows:

  1. Use custom RDP tables, which are limited to EAN32 and EAN36
  2. Use the EAD table with the air RDP table
  3. Use the EAD table with the eRDPml
  4. Use the EAD formula with the RDP table
  5. Use the EAD formula with the eRDPml

For options 2-5, you could either use a standard mix or a custom mix. Of course, most  people would just use a dive computer, and PADI has just announced that the Enriched Air Diver course will use the dive computer as the primary method of calculation, with the RDP methods as an option. The Open Water course is going that way as well, so the tables will eventually be a distant memory.

Just for fun I’ve calculated the dives based on 20 minutes on the Kinghorn to see what the maximum time on the Daryaw would be. With air, we’ve got 12 and 13 minutes. What will it be with Nitrox? I’m going to use the depths of the wrecks as if they were seawater. When I’m doing my own dive planning, I sometimes take advantage of the lower density for fresh water diving, but I’m not going to encourage my students to push the limits to that extent.

1. Custom RDP tables

Both wrecks can be dived with EAN36. You can’t get that information directly from the tables, however, because they are laid down in 10 foot increments. This means that for the Kinghorn you need to use 100 feet as the planning depth, finishing the 20 minutes in repetitive group K. If we used the EAN36 table instead, in the knowledge that at only 95 feet we’re still within our maximum PP02 of 1.4 atmospheres, we come out at repetitive group H. After 45 minutes we’re at E and C respectively.

For the Daryaw at 90 feet, there’s no question that we can use EAN36. This allows 25 or 28 minutes of adjusted no decompression limit, depending on whether we used EAN32 or EAN36 on dive #1. This is definitely much better than the 12 or 13 minutes we got with air.

2. EAD table with Air RDP Table

For this option, we can at least customize our mix to the depth, although the 10 foot increments on both tables will limit the precision with which we can do this. On the Kinghorn we will dive with 34% Oxygen, with which we will have an equivalent air depth of 78 feet. This too will result in us coming out of the water in repetitive group K, dropping to E with the 45 minute surface interval.

On the Daryaw, the 90′ dive will let us use EAN37 (as it’s fresh water we could actually use EAN38, but we’re using the tables here so we go with 37%). The equivalent air depth is 65 feet, which as an E diver will have an adjusted no decompression limit of 25 minutes. Not bad, considering the 10′ increments in both tables, but its at the cost of using non-standard mixes of 34% and 37% rather than getting the same dives in with the more common 32 and 36 percent mixes.

3. EAD table with the eRDPml

This will be very similar to the above, except that we get slight advantage from the fact that the EAD on the Daryaw is 65 feet, because the eRDPml uses 5 foot rather than 10 foot increments. Using this method, we get 29 minutes of adjusted no decompression limit, the longest yet.

4. EAD formula with RDP table

So lets go all the way now. In fresh water, the limits are 36% and 38% for the two wrecks, which gives EAD of 71 feet and 64 feet respectively. Diving the Kinghorn for 20 minutes gives us our old friend repetitive group K,  going to group E after 45 minutes letting us dive the Daryaw for 25 minutes. OK, so no difference here unfortunately we still get a maximum of 25.

5. EAD formula with eRDPml

Using the greater precision of the eRDPml puts us in repetitive group J after dive #1, going down to D after the surface interval. Clearly, the EAN36 table used in part one was a better bet. However, on dive 2 our adjusted NDL is 31 minutes, which is slightly better. So this method wins by a nose.

The bottom line is that Nitrox can be the difference between a really short dive a decent one at 60-100 foot depths, just like they say it is.

By the way, if you really wanted to max out the time, in example 5 you could legally cheat by assuming that the eRDPml was calibrated to salt water, and converting the EADs from fresh to salt. So 71 feet becomes 69 feet. This allows us to spend 33 minutes on the Daryaw. Ladies and gentlemen, we have a winner!

So by playing around a bit, we got 25-33 minutes time, or 12-20 minutes more than with air on the second dive. In practice, most of us are going to use our computers anyway, but the results are going to be similar with much more liberal bottom times allowed when using enriched air.

PADI Pro Weekend: Daryaw Drift Dive June 23, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks.
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The final dive of a fabulous weekend of diving started down the line to the Daryaw for the third time that day. This one, though, was different as the whole team of 11 gathered at the stern (it probably would have made a good picture to see all us hanging there) awaiting the signal to let go. While the current appeared to be quite strong at the surface, at depth I was surprised how slowly we drifted away. The river certainly wasn’t at its peak flow this time.

At a depth of 90 to 100 feet we moseyed along the bottom with a rock wall to our left and a fairly flat bottom below. At one point I found a bottle of Bawls (a highly caffeinated soft drink) and wondered if it was the same bottled I’d found the previous year and then released the previous summer. I placed it on a rock ledge and maybe I’ll find it again next year. Steve found the rear wheels and axle from a tricyle lying in the mud, played with it a while, and then put it down again. Here’s some not very good video of that.

After 25 minutes or so I was surprised that we had not drifted any shallower, and as we were all getting low on air, in a rather ragged fashion we started working our way up the rock wall, where it flattened out at about 30 feet. I shot my signalling tube from that depth and hung for 3 minutes at 15′ before surfacing, to see divers and signalling tubes scattered about here and there. The visibility under water had dropped way down and I’d lost sight of everyone until then.

I floated on the river until it was my turn to be picked up. Lawrence swung the boat around perfectly so that the ladder appeared directly in front of me, and all I didn’t have to swim at all to climb aboard. On the way back I got all my gear packed and stowed so that I could make a quick exit, and after Ed gave us all the paperwork for the specialty Instructor ratings (for me Deep, Wreck, Enriched Air, O2 Provider, Drift, Dry Suit and Digital Underwater Photographer) I was on my way home in reasonably light traffic.

It was a great weekend with a bunch of excellent divers. I learned more about the local shipwrecks, and used some new equipment combinations successfully, including my single tank adapter.

PADI Pro Weekend: Diving the Daryaw, part 2 June 22, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks.
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Dive #2 was also on the Daryaw, so our surface interval was spent moored on the buoy getting ready for the next dive and talking with the divers on the other boats that happened along. This time, we’d also planned a penetration dive, but it was my turn to lead. I used my doubles again, now down to 1700 PSI, but the planned penetration is a short one and there was plenty of safety margin with this much gas.

This time, I was going to lead the way in and lay the line. After our experience with the beacon the day before, we decided it wasn’t worth the trouble. The team planned to meet at the props and then go to the door. Even though Ken and I were right behind him, Steve didn’t notice us at the props, and waited there for Ken and I while we went forward to the door. By the time he realized that we had gone past him, I was well inside the wreck, having mistaken Ken for Steve at the entrance.

To get amidships on the underside of the wreck where the door was, like the day before I dropped to the bottom in the channel between the rocks and the hull on the starboard side. It was there that I noticed it was possible to swim underneath the starboard deck instead of around it, which was well protected from the current and plenty large enough to accommodate a diver wearing doubles. I emerged almost directly under my destination, the door leading into the starboard stern section of the wreck.

I tied the line on the left hand side of the entrance, looping it between the door and a nearby porthole. I think the left is better for this penetration as the best tie-off points inside are to the left of the route to the mechanical room. Once at my destination, I turned to see how Steve was doing and realized that I was alone. Being in possession of redundant air supplies, a guideline, and a relatively undisturbed interior with good visibility I wasn’t bothered by this situation, but didn’t want to hang about. So I looked around inside the mechanical room for a little while before exiting. The room was much larger than I’d previously thought. I hadn’t seen it without a lot of silt before, and there really is a lot to see there. I wish I could have stayed a bit longer, but being alone inside the wreck wasn’t part of my plan, so I reluctantly headed for the exit..

On the way out the line slipped off the reel and started to tangle. Not wanting to “bird nest” the thing, I just stopped for a couple of minutes and patiently untangled it and reeled it in, so I could emerge without embarrassment. The others were waiting at the entrance for me, after which we swam up to the bow.

Part of my mission was to look for other entrances, and it had been reported to me that there was a door somewhere in the bow that was stuck shut and might at some stage be forced open for a  little more exploration. On one dive to the wreck in 2008 I’d found my way into a cavernous section of the bow but the visibility was very poor and I didn’t get properly oriented. Indeed when I exited the area on that dive I found myself about 30 feet from the bow on the starboard side while thinking I was at the bow itself.

This time, the visibility was much better, and after rising up through some spars at deck level it was apparent that most of the bow was taken up by a cargo hold. The perimeter of the hold at deck level was intact and perhaps 4 feet wide, but close inspection revealed no prominent features, and certainly no doors. Not that one would expect to find a door in a cargo hold, I suppose.

Once we’d had our fill of the hold, we agreed to drift over the hull one more time, and doing so, then ascended up to our safety stop, where we ran into Matt and Andrew doing the same thing. You can see the boat floating above Matt in this picture. If you look carefully you can see the ladder hanging down from the stern on the starboard side and a white bumper further to its right.

Matt offgases under the dive boat

Matt offgases under the dive boat

I’m really glad I had a chance to do these two dives on this ship. Firstly, I’ve gained valuable familiarity with the interior and feel much more comfortable in there after my “progressive penetrations” without having more experienced divers watching me. Second, I know my way around the bow of the wreck much better now, and while it too is an overhead environment, the exits are plentiful and easy to reach.

PADI Pro Weekend: Diving the Daryaw, part 1 June 20, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks.
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The Daryaw is cool wreck, although it is not for the inexperienced. It lies in a part of the river where the current can move quickly, is at a depth of 90 feet wedged between rocks, and is upside down, making any attempt at penetration potentially confusing. By now it’s Sunday, June 14th, 2009 and there are 3 of us in the buddy team, with Ken added to the previous day’s pairing of Steve Irwin and me.

Our captain, Lawrence, remembers the night in November 1941 when the Daryaw struck a shoal in the fog. It was visible for two days before slipping below the surface to its current resting place.

There are two lines which lead down to the Daryaw. We used the one I’m most used to, which goes straight down to the props against the current. The other line is much further to port, which in the upside logic of positioning around the wreck, means closer to the Canadian side of the river. This line leads to a rock shelf much shallower than where the wreck lies, then turns about 135 degrees to the left descending diagonally downstream to the props. I’ve only used it once.

Once at the props, the next stop is underneath the wreck – out of the current, almost. You can get there by pulling along one of the two lines running left (i.e. starboard) from the props. The upper one looks like a strong rope, while the lower one is a flimsy flat cotton affair that looks like it might break at any time. It doesn’t, and that’s the one I used, although about half way to the destination I dropped to the bottom into a narrow protected channel where the current was much less and pulled myself along the rocks.

The ship’s stern was built higher than amidships, so the middle of the boat is well off the bottom. I also believe the terrain is a bit higher near the bow, leaving lots of swimming room in and around that area. Most divers spend their time amidships looking around. During my DSAT Tec Deep course I did valve shutdowns, stage bottle drops and pickups, and Scuba unit doffs and dons in that area. This time, however, our destination was inside the ship.

Well up from the bottom there is a door leading astern on the starboard side. We had agreed before getting in the water that I would enter the wreck and wait by the door. As the only one with a long hose and redundant air supply (I was back to using my doubles) it made sense that I would be available to the less well equipped divers as soon as they were in. Next Steve came in, and he had planned to affix a small flashing beacon to a convenient spot near the door.

I was surprised that he didn’t tie off his line right at the door as we’d agreed, but I think he was focused (fixated?) on the beacon. He then chose the second post, about 8 feet into the wreck to hang it, but could not make it fast. After a couple of minutes he handed it to and tied off his penetration line on the same post. I managed to get the beacon attached loosely to the first post. It uses a Velcro loop, and seeing which side has hooks and which side has eyes in the darkness wasn’t all that easy.

Ken then entered and I let him past, and we all followed Steve’s lead through the same path we’d taken during wreck training. However, I was the only one of us who’d been into the wreck since then, spending two hours inside it last summer as a safety diver, and saw that Steve had swum past the door leading to our intended destination and entered two doors further down. I don’t know what’s in there – Steve said there wasn’t much, but by that time I was trying to signal to the guys to turn around and leave. As we’d missed our planned destination, I thought it was reasonable to abort the penetration.

Once I saw they were following, I led the team in the other direction, then waited at the door for everyone to exit safely before going out myself. From there, we made our way under the ship to the bow by pulling ourselves along the bottom and various lines that were placed there, and after observing a small school of large fish near the bow, ascended over the ship and drifted in the current along the hull back to the screws. I realized that we’d done this a bit early in the dive as I still had about 2/3rds of my air left, and started to go back amidships to look around some more, but both Steve and Ken were low on air so we headed back up the line for our safety stop.

The total dive time including the stop was 38 minutes with a maximum depth of 90 feet. We were able to do this thanks to the extra capacity of EAN32 in our tanks.  It was a nice sunny day but the water temperature of course was unchanged at 56F (13C) so most of us were in dry suits. I was back on the boat at 11:03. Matt “Sharpeye” Lepp, who was diving with Andrew, had found the small black plastic cap from Steve’s regulator near the bow and returned it to him on the boat. Steve also mentioned he lost a double-ended clip somewhere on the dive.

PADI Pro Weekend: Diving the Kinghorn June 19, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks.
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The Kinghorn is one of the wrecks I’ve dived the most, located conveniently on the Canadian side of the St. Lawrence River not far from the Caigers dock and directly in front of the dock in Rockport, Ontario from where the wreck can be shore dived by those with plenty of gas and a willingness to incur some decompression obligation.

Our dive on it was pretty straightforward. Buddy Steve Irwin and I pulled ourselves down the line from the mooring buoy to a concrete block a little off the starboard bow. There is also a line that runs to the stern that I’ve used on other occasions. On the short swim over to the wreck, I noticed that a pair of tacky lawn ornaments had been placed there since my last visit. We then made our way with the mild current the length of the ship to the stern, and entered through the first deck opening, which is partially covered by a ship’s wheel.

We swam slowly in the darkness of the interior. It was a dull day so not a lot of light penetrated through the many openings in the ship’s deck. Some days, when the sun is bright, the interplay of light and shadow inside the wreck is quite beautiful. This time, we contented ourselves with a pleasant meander inside, stopping to inspect the anachronistic “artefacts” placed there over the years by divers wanted to add some entertainment value to the experience.

Once we reached the last opening near the bow, we exited and let ourselves drift back again to the stern, and went in one more time. At a maximum depth of 95 feet, this wreck shouldn’t been taken lightly, but now having dived it more than half a dozen times it’s now like an old friend and I feel at ease there.

As my doubles had been almost empty from diving the Keystorm and the America, I’d switched over to one of my AL80 tanks filled with EAN31. This involved removing the doubles from my backplate and harness, and installing my newly acquired single tank adapter and the tank bands from my Seaquest Raider. I used an 18 pound weight belt (vs. no weight with my double steel tanks) which was more than enough, and the entire combination felt comfortable right from the start. Now that I’ve tried it, I might not use my Seaquest Raider again, and start using one of the shop rental BC units for instruction in the pool, or buy something used and cheap.

With both of us on Nitrox, we did not require decompression for the half hour dive despite it being the third dive of the day. Our dive lasted 34 minutes including the 3 minute safety stop, and I emerged with 400 PSI remaining in my tank, having started with 3000. While this is plenty of reserve for a single diver, if someone else needed air in an emergency just before ascending then likely we would have been out of air before the end of the safety stop, especially with the increased consumption due to the increased anxiety of the situation. Something to consider when pushing the reserves too hard.

PADI Pro Weekend: Diving the America June 18, 2009

Posted by Chris Sullivan in Dive Log, Shipwrecks.
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The America is a common second dive after the Keystorm. It’s a medium depth dive with lots of nooks and crannies to explore. Care is required not to touch the bottom in the wrong places as there is an oily residue that clings to a diver’s equipment if touched.

Buddy Steve Irwin and I splashed in just after 1 PM on Saturday June 13th, 2009 after a one hour surface interval. He had a fresh new steel 95 to hold his Nitrox while I used my doubles again (also with EAN32), having about the same number of cubic feet left as he, starting the dive with 1700 PSI.

The lines leading down to the wreck forked a couple of times and I made a note of the configuration. I’d dived the wreck in 2008 and remembered having to backtrack along the lines at one point after trying to exit a different way than we’d entered.

The wreck is a barge, which exploded during a blasting operation. There are 4 stabilization posts on the ship, 3 of which are still upright, and I took a close look at one while exploring the top side of the wreck, which otherwise didn’t seem to have much to look at.

Underneath is another story. There are lots of wide open spaces under the wreck with easy penetrations that don’t require (in my opinion, be your own judge) penetration lines. There are several places where you can easily cross from one side of the wreck to the other, and lots of fixtures still attached to look at. Steve and I did this several time in several ways in the course of the dive.

Navigating back to the entry point is pretty easy since it’s close to a ladder which sticks up from the bottom near the side of the wreck. On the way back up I remembered one of the T-intersections that we’d seen on the way down, and made sure we went back the same way. I was a little unsure of myself as a little further on there was a huge anchor lying by the line which I hadn’t noticed on the way down. Fortunately, we emerged from our 45 minute dive at the same place where we’d started. The maximum depth of this dive was 79 feet and the current was quite mild that day.

I tried to snap some pictures but nothing really turned out. My camera doesn’t behave well in low light and most of the deeper dives in Ontario are poorly lit. Eyes adapt much better than cameras. About all I have to show for the dive is this close-up of one of the props.

The America

The America

It’s official June 17, 2009

Posted by Chris Sullivan in Training.
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I’m now officially a PADI instructor and can change my bio. This from the PADI members’ web site.

Core Credentials

Rating Date
Open Water Scuba Instructor 16-06-09 5:33:32 PM