Who Cares if the Rebreather Has Integrated Deco

For some time now, Innerspace Systems has been working on a Megalodon head called APECS 3 that supports integrated decompression. As with any major software / hardware engineering project, there have been some delays, which has Meg owners clambering for information about when it will come out. It’s amazing how so many of these rebreather divers are pestering the company and acting like a bunch of kids a few days before Christmas. What I don’t really understand is why people are so anxious.

It’s not that I wouldn’t like to have integrated deco, but I really don’t see it as being all that big a deal. When software gets more complex it also gets more buggy, which is why I’m pretty happy having a very basic loop controller. Keeping the deco on a different unit like a VR3 is a nice modular system, and besides, I don’t really even use the computer on really deep dives.

When I plan a bigger dive, I do it like this:

  • Work out the details on the laptop
  • Cut the tables and laminate them (wrist mounted slate)
  • Cut bailout tables and laminate them (also on wrist)
  • Fill 02 and Diluent
  • Fill bailout using thirds
  • Do the dive as it was planned and as it appears on my wrist.

While I use the computer to validate my deco schedule, it is really only there for backup.

Again, it would be nice to have integrated deco, but IMHO, you should not do big dives if you can’t maintain a setpoint. Provided you can, or even if you depend on your loop controller to do it, your actual setpoint will match that on your computer. Everything should jive and you can validate the deco schedule on your wrist.

It’s tempting just to jump in, do a gnarly dive and depend on your computer to get you out of it, but doing so ignores some of the basic safety precautions of technical diving like proper gas management, which is a risk that I really don’t feel comfortable taking.

How Scuba Tanks are Made

I was trying to talk Justin into getting a set of steel tanks so that he could band them together when we got onto the subject of how scuba tanks are made. He mentioned some videos of the process he had found, and sent them along to me. It’s really a pretty amazing process. Especially the way they extrude an entire tank out of a single block of aluminum.

The first video shows how aluminum tanks are made, while the second shows the process for steel tanks.

Revillagigedo Archipelago Dive Log – Day 6

On our sixth and final day of diving at the Socorro Islands, We headed back to San Benedicto to dive at “The Canyon” and, we had hoped, another stone pillar rising up from the sea floor called “The Boiler”. By this time in the trip, the weather had turned fairly bad for Mexico, and we were dealing with quite a bit of swell. As usual, we got up and had our pre-breakfast breakfast (they feed you well on the Nautilus) and started getting ready to dive. Since this was my last day of diving on the trip, I had made up my mind to do some deeper dives on my rebreather.

Keeping in mind that I did not have access to any TRIMIX I decided that I would not go much deeper than 155 feet, which is the point on rebreathers where you really should start using Helium in your mix. This is not only to buffer the narcosis, but because going deeper than 155 using air diluent at a 1.3 setpoint causes you to actually incur more decompression obligation than if you were simply breathing straight air.

The other thing to remember when doing deeper rebreather dives using air diluent is that the effects of narcosis can be much more troubling than when diving open circuit. When you are breathing off a tank, you feel a bit of narcosis in your head and you know exactly what it is and, assuming you have acclimated yourself to it slowly and over progressively deeper dives, how to deal with it. You can accept the narcosis and go on about your dive.

On a rebreather, however, you are breathing off a recirculating loop which is monitored by oxygen sensors. You constantly check the status of this loop and you depend on the sensors to give you accurate information, quite literally, with your life. Should you have too little or too much oxygen in your loop, your body will give you very little warning before you either fall asleep or go into convulsions. For this reason, you are not only constantly monitoring your loop, but also how you are feeling. In deep water, it becomes easy to ask yourself if the narcosis you think you are feeling might actually be lightheadedness from a C02 breakthrough or impending hypoxia.

Anyhow, to make a long story short, I really wished I had some helium, but I didn’t, so I was stuck going not much deeper then 155. On the first dive of the day, Rich and I went down the shotline, snaked around the outside of the canyon wall, and headed down the gentle-sloping topography. As we descended, there were a lot of little rock platforms that came up about 10 feet off the sea floor. We made our way from one of these to the next until we finally found ourselves at the top of one in exactly 150 feet. We hung out for a while, looking at several white-tip reef sharks, but finally decided to head back up into shallower water. We met up with our friends at about 80 feet where we all started making our way back to the line. The entire dive lasted 50 minuets and it was the deepest dive I had done on my Meg to date.

The second dive of the day was supposed to be at a site called “The Boiler“, a stone pillar jutting up from the seabed, and peaking just slightly below the surface of the water. It is an extremely exposed site, and it became clear on the boat ride out that there was no way we would be diving it. At one point the skiff broke loose from the Nautilus and the crew had to go rescue it. I’m also sad to report that a very nice camera took a digger because of the high seas, breaking the dome and bending the lens. Overall, it was a very bad boat ride!

Cutting our losses, we returned to the Canyon, which was in fairly protected waters and still very divable. The Nautilus anchored directly at the dive site, so we could splash right off the back and stay down for as long as we liked. The divemasters had also rigged a trapeze underneath the Nautilus at about 30 feet, allowing divers to pull themselves from the dive deck on the stern to the main anchor line on the bow. I made my way down the line, and as before I rounded the wall and headed down the bottom, making my way from platform to platform. On this dive, I decided to go alone and stay down a little longer than before. I stopped when I arrived at 160 feet, and stayed there for about 5 minuets. As before I saw some sharks, but little else, and finally decided to head back. I saw a few other divers on my way back, but not wanting to get into too much deco, I decided to leisurely make my way back to the anchor and complete my decompression.

All told, I stayed down for an hour and decompressed for 20 minuets, adding about 10 extra on pure oxygen just for safety. Many of the other divers decided to do one more dive before we pulled anchor and headed back to Cabo, but I was happy to stay dry. My last dive had been great fun, and I thought it a great way to say goodbye to the Revillagigedo Archipelago.

That evening, we began the long, 27 hour journey back. The next day we spent cleaning gear, settling tabs, sharing pictures and videos and generally chatting about a great trip. The ocean was quite rough, so I spent a great deal of the ride back with a twinge of seasickness, but nothing too bad. We finally arrived in Cabo San Lucas at about 10:30 PM. We all wanted to get off the boat pretty badly, so a bunch of us headed out to Cabo Wabo to see if we could find Sammy Hagar, or at least some burritos and tequila. Luckily we found both, but we headed Sten’s warnings and stayed away from the police and the people looking to make “new friends”. Cabo really is just a big old party.

We made our way back to the boat by midnight, and headed out to the airport the next day at 9:00AM and just like that the trip was over. It was wonderful diving and wonderful people. I highly recommend the Socorro Islands to anyone who loves diving, and loves large sea creatures!

Geo Dive Blogging 101

My recent posts and dive log entries about my trip to the Socorro Islands have gotten a lot of people asking about how I create the map with post excerpts on this website. I’ve been slow about writing it up because quite frankly the process has been changing over the past week or so. I started doing this as a way of logging my dives, which I have not done since I was a teenager. When people ask how many dives I have, I honestly have to answer that I don’t know because I stopped logging just after dive number 200. Since dive log book had no real value to me, I found no reason to continue using them. Lately, however, I began asking myself how I might log my dives in a way that could be valuable to both me, and others as well.

I had a few requirements.

  • First, I wanted to use this blog as my dive log book.
  • Secondly, I wanted to record and display the GPS coordinates of the dive site. I also wanted to leverage the Google Maps API to display these sites on a map.
  • Finally, I wanted to record and display the information that I believe is important about the dive. For instance, I don’t care to record the water temperature and whether or not I wore a hood, but I did want to record and display information about gas choice, max depth and bottom time. I also wanted to record and present information about deco schedule.

The first phase, and the only one that I have completed thus far is to record and present GPS information about the dive site. When I first implemented this, a total of three WordPress plugins were required. “Geo Mashup” was used to create the map page with the post excerpts, “Geo” was used to enter the GPS coordinates into the “wp_postmeta” table, and “bsuite-geocode” was used to search the post text for links to Google Maps, strip out the GPS coordinates and enter them into “wp_postmets” if they exist. It also created a “Location” link to the post excerpt on the map page.

This was all before the final release of Geo Mashup 1.0, however. This is now the ONLY plugin that is required to create the map with post excerpts. In fact, running either “Geo” or “bsuite-geocode” will prevent “Geo Mashup” from working correctly after version 1.0.

Version 1.0.1 of the Geo Mashup plugin creates a nice little Google Map in your “Edit Post” or “Write Post” window that can easily be used to enter GPS data about the post. The only downside is that there is no way to display a link to the map from your post without adding the following code to the loop in your theme:

< ?php GeoMashup::show_on_map_link('link_text') ?>

Sadly, the “bsuite” plugin I use to create the “Tags” and “Related” stories section at the end of my posts takes over the bottom of the post entirely, meaning that map link would need to go below that. Since I think the “Related” section ends the post nicely, I have not incorporated this code into my theme yet. I have brought this up with Casey, who says he will allow the user to control where the bsuite functions display in the next version, which is soon to come out.

Clearly I still have some work to do with respect to displaying dive information and deco graphs, but that should be coming soon. Hopefully I will be able to release a DiveLog WordPress plugin once I get it all hammered out. Stay tuned.

Revillagigedo Archipelago Dive Log – Day 5

We steamed the better part of the night from Roca Partida back to the island of Socorro where we would be diving a site called “Cabo Pierce” and another stone pillar called “La Pitite Boiler”. Normally we would have made our way to these sites on Days 2 and 3, but we wanted to take advantage of the calm weather on those days to dive the much more exposed Roca Partida. As the Captain predicted, the wind and swell were definitely beginning to pick up and the relative protection of the island was certainly welcome. By now, however, I had found my sea legs, and any nausea I had felt during the first few days had long since passed. I did, however, sleep poorly and as my eyes cracked open I found myself entirely unprepared for the day at hand. Remembering that this trip was expensive and that each diving was costing me about $150, I forcibly dragged myself out of bed, albeit too late to get my rebreather ready to dive.

So it was that I found myself on open circuit SCUBA gear again that morning, which was just as well because I was tired and groggy thru-out the entire first dive and there was a LOT of current. It’s hard to say if it was because I was tired and not paying close enough attention, or simply because there was not much to see, but the first dive at “Cabo Pierce” was fairly uneventful and my photography endeavors resulted in little other than a few pictures of fish and an Octopus. As with many dive sites at the Revillagigedo Archipelago, this “Cabo Pierce” is a lava flow that takes the form of walls. The dive site itself starts at about 80 feet, making it a fairly deep dive if your intention is to avoid decompression obligations. My maximum depth on this dive ended up being 100 feet, but I stayed down for 45 minuets and racked up a little bit of deco… I was breathing air after all.

After getting back to the boat, drinking a little coffee and eating breakfast I went to work straight away on putting my rebreather together and pre-diving it. Diving Rebreathers is a form of technical diving and it requires a lot more work and attention to detail than open circuit diving. Because of this, rebreather divers are frequently the target of taunting and snide comments by open circuit divers. You almost get to the point where you stop hearing it when people say “my, those things certainly are a lot of work”, or “seeing how much work those things are to dive, I think I’ll stick with my traditional SCUBA gear”. Perhaps they’re just jealous. Technical diving is not for everyone and since most people don’t want to do long, deep dives, they’re probably better off with standard equipment and techniques anyhow. All told, I spent about an hour getting my rig ready to dive and finished just in time to make the second dive of the day. Not wanting to fight with the strong currents we encountered on the first dive, I decided to do this one by myself and explore the lava formations inside the large cove near the island itself. I jumped right off the back of the Nautilus, descended to the sandy bottom at 100 feet and started swimming towards the island, keeping the sun at my left for reference.

As I neared the island, I found myself in about 50 feet of water, both hearing and feeling the songs of Humpback Whales. We’d heard Humpbacks on many of our other dives, but in the case, the sounds were amazingly loud and I could actually feel the low frequency waves travel through my body and head. I can only imagine that the creature itself must have been very close, but despite constantly looking, I was unable to see it. The sounds diminished as I neared the island, and I found that the shore was not so much the sheer wall I had imagined, as it was a series of walls that were formed by lava flows. I didn’t see much in the way of animals, but thoroughly enjoyed exploring the flows and lava formations. At one point I even found a small cave which started in about 40 feet of water and ended roughly 40 feet back and 30 feet deep. All told, I stayed down for 1 hour and reached a maximum depth of 100 feet.

For the third and last dive of the day we went to a site called “La Pitite Boiler”. This site is a small stone pillar that begins on the sea floor at 130 feet, and extends up to about 5 feet below the surface. It is named for the way the water seems to boil as the waves pass over it, briefly exposing the peak and then submerging it again. We descended directly to the bottom at 130 feet and basically swam laps around the towering stone getting shallower and shallower on each pass. The surface was fairly rough, but there was little to no current and the dive was extremely fun. We saw quite a few Moray eels, although the larger animals eluded us. It’s hard to say exactly how many laps I swam around the pillar, but I stayed in the water for an hour and enjoyed every second of it. When I did decide to surface, I did so mostly because I didn’t want to keep the other divers waiting and because it was getting dark. I could have happily stayed down for another hour!

We pulled anchor and started heading back to the island of San Benidicto for our last day of diving before dinner. The seas were rough, which made for some interesting displays of plate and cup handling skills during our meal. I had a couple of Gin and Tonics and headed off to bed. Since we were going back to “The Canyon” I had designs on doing some deeper dives in the morning.

Revillagigedo Archipelago Dive Log – Day 4

With only three days left to dive on our trip, I was admittedly wishing that we had chosen another dive site for the day. My primary goal of this trip was to spend a great deal of time on my rebreather, but the swell was simply too great, and I was diving open circuit to avoid the inevitable counterlung volume issues that came along with the conditions. I guess I should come out and say that I am a technical diver and thus, the greatest draw to me is deep water and not necessarily the interaction with animals for which Roca Partida is most known. This, combined with the fact that we had seen fairly few large Mantas and Sharks on our first day here had me pining for some walls in more protected water.

John, however had mentioned the night before that we WOULD see more creatures today, and that there was simply no way around it. We joked with him that he had sent out a telepathic signal to them, and that they were surely swimming toward us now, but unlikely to arrive before our departure. We all had a chuckle at the idea of hundreds of confused Pelagics swimming around island several days later, wondering where John had gotten off to. Telepathy or not, whatever he did worked because the number of large animals we saw on day two at Roca Partida made the first day seem like diving in a sterile lake.

Because I was still diving open circuit, and had little to devote my attention to other than just diving, I decided to try my hand again at photography. Unlike the day before, but camera worked perfectly and most of my underwater shots from the trip are from this day. I even took a video of one of the Mantas that came in close and interacted with us.

The first dive of the day was wonderful. I still found myself looking down into the depths, wanting to dive to the peak of the submerged volcano at 250 feet, but the fact that we saw a large black Manta and a group of Hammerhead sharks right way made staying in shallow water a great deal easier. I actually only went to a maximum depth of 85 feet on this dive, but there was so much to keep my interest that I stayed in the water for nearly an hour.

The second dive was much the same, although I descended to 95 feet this time in hopes of finding some more Hmmerheads. I found a great number of Silky Sharks, but the Hammerheads eluded me. I ascended to around 50 feet where I had another wonderful interaction with a black Manta and found a lot of large Tuna. I finished out my 1 hour dive in the 40 to 50 foot range and enjoyed taking in the scenery.

There really is something about doing dives that don’t have a visible bottom that makes you feel like you can fly. Many of the divers described the Mantas as Sirens that call you out into the blue away from the visible topography, and I can attest that they most certainly do. I think of myself as a very disciplined diver who maintains awareness of his surroundings and topography at all times, but when a large Chevron Manta showed up on our third and final dive at Roca Partida, I was amased at how, after only what seemed like a kick or two towards him, I was much further from the island than I expected to be. This is not to say that I could not see the topography, but it made it very clear how one might get into trouble swimming with Mantas. As I was still fairly close to the island, I decided to simply hover at 85 feet in the water column and let the giant Manta make several passes at me. As an added bonus we had some large Silvertip Reef Sharks make passes by us as well. All told, I stayed in the water for an hour, and reached a maximum depth of 90 feet. It was a wonderful way to say goodbye to this amazing dive site.

That night we pulled anchor and headed back to Socorro for another day of diving. I was tired, so I slept well despite the constant rumble of the boat’s engines.

Revillagigedo Archipelago Dive Log – Day 3

Roca Partida is not so much an island as it is a small lava plug from an extinct volcano that has otherwise been eroded away into the sea. This rock pillar is only about 300 feet across at its widest point, and it descends almost vertically to a depth of 250 feet, where only then does it begin to take on the topography of a typical mountainous volcano. Situated in the open ocean, 60 nautical miles from the nearest land, the only inhabitance of this failing island are a great many birds which is evidenced by the snow-like white shrouding of all but the most wave-beaten rock. While there is not much in the way life above the surface at this site, it is known among divers for its nearly constant traffic of Manta Rays, Sharks and Tuna. Roca Partida is, in fact, generally thought to be the best dive site the Revillagigedo Archipelago has to offer.

Because of the remote and exposed location of this dive site it is important to have good weather or the swell becomes too large, and the site undivable. So, when the weather report came back fovorable for the next few days the decision was made to pull anchor and begin the 60 mile trip to Roca Partida, where we would spend the next few days diving. Because these islands have not been re-charted since the advent of GPS, the moving map displays on the ship are not always totally accurate and the crew prefers not to maneuver the boat around the tiny island at night if it can be avoided. I, myself, got somewhat confused at one point when I turned on my little Garmin GPS and found that it had me placed right on the beach of Socorro when I was quite clearly standing on the deck on the Nautilus Explorer! Anyhow, the trip would take about 12 hours, so we decided to leave Socorro for Roca Partida after dinner so that the sun would be up by the time we arrived.

To my surprise, the dive briefing that night included very little of Sten’s humor and joking, but instead a lot of stern warning about not loosing visual reference to the topography and the importance of surfacing near the island. Because it is basically an open-ocean dive site and there is no shotline, a diver that surfaces very far from the Zodiac or skiff is difficult to see, and can easily become lost at sea. While we all carried surface marker buoys (SMB’s) and mirrors to mitigate the risk, the warning was clear. “Never lose the topography underwater. If you become disoriented, surface without a safety stop and inflate your SMB.” Sten saved the most chilling warning for last, reminding us that if we became lost the only Boat looking for us would be the one we were on, and that if we were not found by dark we would not be found.

That night I did not sleep well, and woke up entirely too late to get my rebreather configured to make the first dive. Instead, I lounged around, drank coffee, and leisurely pre-dove my rig. Rich, on the other hand made the first dive and mentioned that maintaining counterlung volume was difficult above 30 feet because of the substantial swell. We both made the decision to dive open circuit at this site and I carefully packed up my Meg beneath my bunk.

My first dive of the day was great fun, but something in my brain forgot what it was to dive standard SCUBA gear, and I emptied my tank to 500 PSI after only 45 minuets in the water. You can breathe as hard as you like on rebreathers, but not so on open circuit. I had borrowed my gear from the boat, and was surprised to look down and see that my borrowed dive computer, a TUSA IMPREX, read that I was at 155 feet! My trusty VR3, a dive computer that I have depended on for years, and one that has been used on many a gnarly tech dive read only 100 feet, so that was the one I decided to trust. The IMPREX racked up quite a deco obligation, so I went ahead an cleared it while playing around in 30 feet of water or so. The 30 foot level turned out to be the most interesting anyhow because we saw a large Manta, some White Tip Reef Sharks and some large Tuna towards the end of the dive. It was difficult to maintain a constant depth, however, because of the strong surge and swell.

The second dive of the day was much the same as the first, except my camera ran out of batteries about half way through the dive and I did not consume nearly as much gas. By this time I had ditched borrowed regulator in favor of another borrowed regulator, and no longer had to suffer the greatly exaggerated depth displayed by the IMPREX. I swam a total of two laps around the island at a maximum depth of 100 feet, but saw little other than a few sharks and large groups of bait fish. The entire dive lasted about 45 minuets.

By the third and final dive of the day, it was getting dark, and again, we saw only sharks. My camera was working perfectly, but I had too little light for much other than macro shots on the rock. I did get some interesting pictures of little shark dens where juvenile White Tips would gather to rest, sometimes among Moray Eels. Again, I circled the island two times at a maximum depth of 120 feet, and the dive lasted 45 minuets.

Roca Partida did seem to be a great dive site, but at the end of the first day my feeling was that it had been hyped quite a lot. We had only seen Mantas on the first dive, and I was a little unhappy that I didn’t have any helium with which to dive down to the are where the pillar leveled off at 250 feet. The conditions were rough, but not nearly so difficult as had been let on, and a part of me wished we were not spending two days there. I had no way of knowing at the time, but the next day would do a lot to change my mind!