Monday, April 29, 2013

Rebreather opens up a whole new level of scuba diving

Like many divers, Mike Lynch anticipated his venture into the great blue beyond following his open water certification would be peaceful, serene and quiet.
Well, two outta three ain’t bad.
While scuba diving is peaceful and serene, it’s not always quiet, thanks to the never-ending pulse of expelled breaths and the resulting bubbles escaping past the diver’s ear. Breathing air in from a pressurized tank and expelling used air into the water column has always been a part of diving in general and scuba diving in particular.
But for serious divers, and those with both the skills and the disposable income, rebreathers offer a panacea of underwater enjoyment.
In the past year, Lynch, a diving friend of mine who works with Bruno’s Dive Shop in Clinton Township and Titan Dive Group, became a certified rebreather diver, and the stories he has to tell are amazing. Four-hour cave dives with an average depth of 120 feet and such quiet tranquility that he can hear the water moving around in the cave system and rocks cracking on each other as they roll around in moving water. Fish swimming right up to his mask to see their reflection because they aren’t scared away by expelled bubbles.
“It brings you into a whole new world of diving,” Lynch said.
Lynch, repping Titan at the Great Lakes Shipwreck Festival in March, gave me an up-close and personal explanation of how the rebreather works.
In the most basic terms, the rebreather uses two tanks, one containing pure oxygen, and the other containing regular air used as “filler.” Each tank is smaller than a traditional scuba tank. With each breath, the used air is recirculated using a scrubber to remove the carbon dioxide, and additional oxygen is added to the “filler” air. The system is constantly evaluating the user’s gas needs based not only upon their own metabolic rate, but also things like the dive depth. According to Lynch, it creates a perfect nitrox mix for the entire dive.
It is a much, much more efficient way to use gas, since it is all recycled and reused. A typical “open circuit” scuba unit, with expelled bubbles, wastes a significant amount of oxygen. In a typical breath, only about 4-5 percent of the oxygen is used, and the rest is expelled into the water. With a rebreather, that unused oxygen is pushed back in the system and mixed with the filler air and oxygen. Lynch said that during his four-hour cave dive at an average of 120 feet, he only used eight cubic feet of oxygen.
While the idea and the concept of rebreathers have been around for more than 200 years, mass-produced recreational rebreathers have only been around for a little more than 20 years. The last 10-15 years have seen significant technological advancement.
Nevertheless, cost remains an issue. Lynch said a diver looking to get into rebreather technology can expect to spend about $10,000 for the equipment, the training and the gas to get started.
In the video above is my interview with Mike Lynch and our discussion about rebreathers.

Monday, April 22, 2013

State police trooper recounts Cessna crash in Lake Michigan in which two people were trapped in the back seat

Michigan State Police Sgt. Bill House admits he has seen a lot and “been in a lot of bad places” in his 13 years as a member of the force’s underwater rescue and recovery unit.
But one incident still gets to him and chokes him up nearly three years after it occurred: That is the case of a Cessna 206 that crashed in Lake Michigan about four miles off the coast of Ludington on the morning of July 23, 2010. The crash killed four of the five passengers. But it was the way that two of the victims were killed that House acknowledges bothers him to this day.
“I think of it now and the thought of them and what went on, yeah, it still bothers me. I can still see their faces as clear as the day it happened,” House said.
The tragic story began on July 23, 2010, when pilot Jerry Freed, co-pilot Earl Davidson, medical doctor James Hall, cancer patient Donald Pavlik, who was superintendent of the Alma Public Schools, and his wife Irene set out on a flight from Ludington to the Mayo Clinic in Rochester, Minn., where Pavlik was to receive cancer treatment. The aircraft developed engine trouble, eventually determined to be a faulty fuel filter. The pilot turned around in the hopes of making it back to Ludington.
They never made it.
The aircraft crashed into the lake that morning. While attempting to land the plane in the lake, the pilot lowered the flaps to flare the plane out. The Cessna hit the water, the engine was ripped off, and the fuselage flipped upside down. The pilots and the doctor, who were all sitting in the front seat, got out. Pavlik and his wife remained inside.  Because the flaps were locked into their extended position, blocking the rear door, they were prevented from opening it. The flaps couldn’t be moved because the engine was ripped off the plane.
“They were basically trapped in the plane,” House said.
Six days later, Sgt. House and his dive team’s side-scan sonar s made contact with the plane, finding it in 173 feet of water, about three to four miles from the shore between Big Sable Point and Ludington harbor. The Pavliks were still in the back seat -- Don Pavlik still strapped in his seat belt, Irene Pavik resting on his lap.
“It looked like he was hugging her. And it looked like she was trying to get the door open,” House said, his voice choking at the memory.
House and his dive team were actually fairly close to the accident scene when the plane went down. Normally based in Coldwater, House and other rescue team divers were training in Rodgers City when they got the call and immediately headed toward Ludington. They gathered information from the ELT (emergency locator transmitter) that was activated when the plane hit water. Within six hours of the plane going down, the dive team was on the water, setting up a square-mile perimeter grid around the beacon and began side-scan sonar searching. The search came up empty.
The team headed back to shore, talked to a charter boat captain who had seen the plane go down, looked at the FAA flight path that had been recorded prior to the plane dropping below radar and received information from the pilot, who had been picked up by a nearby boat. The team went back out and set up a two-square-mile grid with two crews working 24-hour shifts in an attempt to locate the aircraft. In addition to the difficult environment, the search was hampered by the sonar equipment becoming tangled in commercial fishing nets.
Finally, in the early evening hours of July 29, the crew found the plane upright on the bottom of the lake and the engine nearby. The first recovery dive took place at 7:20 p.m. That’s when divers found the Pavlik’s bodies still seated inside the plane and the reason why they couldn’t open the rear door.  The following morning, the dive team cut the flap actuator rod that held the flaps in the open position and recovered Irene Pavlik. The resulting silt from removing Mrs. Pavlik left zero visibility. That, combined with floating luggage, entangled medical equipment, the width of the diver’s double tanks and the narrowness of the doorway made it impossible to remove Mr. Pavlik. He was recovered later that day.
On July 31, Dr. James Hall was recovered nearby the plane, and on Aug. 1, Earl Davidson’s body was recovered, also near the plane. Presumably, both men drowned sometime after exiting the plane. Only the pilot survived the accident.
It was the deepest recovery dive since the inception of the Michigan State Police underwater rescue unit in 1957, and House’s deepest personal dive. It was also fraught with difficulty, dealing with the environment, the lack of visibility, the wind and the waves and its location so far offshore.
But as is the nature of his job, each day has its rewards and its heartbreak.
“It’s one of those bittersweet things. I love diving. I love state police diving and the recovery work because somebody’s got to do it,” House said. “I’ve been told ‘this is a gravesite, shouldn’t you leave it alone?’ But people want their loved ones back, and so that’s part of it you feel good about. You are excited when you got them out of the plane, but it’s also very tragic.”

Wednesday, April 10, 2013

Alpena-Amberley land bridge reveals more evidence of prehistoric caribou hunting from 100 feet below the surface of Lake Huron

Dr. John O’Shea has a bottle of Scotch whiskey on the desk in his office, a gift from a colleague. The problem is, he’s not allowed to open it.
Not allowed, that is, until the colleague who gave it to him gives him the OK.
Since the summer of 2009, O’Shea, the curator of Great Lakes Archaeology in the Museum of Anthropology at the University of Michigan, has led a study of the Alpena-Amberley ridge, a 72-square mile post-Ice Age land bridge that once connected what is now Michigan’s northeastern Lower Peninsula near Alpena, with Point Clark in southwest Ontario about 9,000 years ago. Today, that ridge sits 100 feet below the water line at the bottom of Lake Huron.
In the 3-1/2 years his team has been studying the area, it has found compelling evidence that both caribou and mastodon used the ridge as a semi-annual migration path, and that humans, categorized as Paleoindian and Early Archaic hunters, devised ways to hunt and kill the animals on the ridge. But a skeptical colleague, that’s right, the one bearing the gift of Scotch, won’t be convinced until the group finds an arrowhead or a spearpoint, thereby in his mind confirming O’Shea’s theory.
“I want to be out there until I find that spearhead and I can open that bottle of Lagavulin,” O’Shea said with a laugh. “We’ve convinced a lot of skeptical critics that this probably is what was going on. The dates (carbon dating of wood poles found to be about 9,000 years old) are coming in, the simulation is working. Science is incremental, you’re always adding things together. But the pieces are falling together in a really nice way. So I’m very enthusiastic about this summer’s work that we will collect even more stuff.”
O’Shea has been a frequent visitor at the annual Great Lakes Shipwreck Festival, and once again spoke to a packed room, updating listeners on scientific findings in 2012.
On older nautical charts, the area including the ridge is labeled as the Six Fathom Shoal, and it once divided the Lake Huron basin into two distinct lakes, the largest of which is called Lake Stanley. Scientists believe the ridge exists because it is composed of limestones and dolomites, materials so hard that even the mighty glaciers that destroyed everything their path couldn’t cut into it.
While the ridge area includes the prehistoric Lake Stanley, Lake Chippewa, the forerunner to Lake Michigan sat to the west. Prior to the ice melt that eventually covered the Alpena-Amberly ridge, those two lakes did not connect at the Straits of Mackinac like they do today.
A computer rendering of the Alpena-Amberley land ridge, a 75-square mile ridge that once connected Michigan's Lower Peninsula to southwest Ontario. The green area represents the current water line of Lake Huron.
In years past, the team had found wooden poles, perhaps used to hang meat, that date to about 9,000 years ago. They found stone structures probably used as hunting blinds, caches or pits and “drive lanes” made by a linear path of rocks that would bring the animals close enough that hunters could attack them with spears and lances.
In 2012, the team discovered additional wood samples, potential fireplaces, charcoal, and in core samples flakeage or micro-debitage, stone microfragments made when chipping away at stone or rock to make tools, weapons or other implements. The microfragments are determined to be manmade since the way they are shaped couldn’t have happened naturally. The team is also transitioning from discovering artifacts to determining how the people of that time period lived.
Since it was during the post-Ice Age time period, the climate was milder than the Ice Age, but still bitterly cold with miserable conditions along the ridge. Those "warmer" conditions were comparably pleasant for the caribou and their thick hides. The subarctic tundra would have had developing grass areas, intermittent marshes and a scatter of coniferous trees, while the water’s edge would have provided various types of vegetation. The windy conditions would have given them relief from flies that bothered them during the warmer seasons. As for the hunters, the confined nature of the ridge would have provided a substantial element of predictability regarding herd movement which would have been of great value to them.
“These people probably lived in the Lower Peninsula, closer to the middle of the modern-day lake since the lakes were so much shallower then,” O’Shea said. “They probably only came out to the ridge to hunt. Maybe they would come out by sled in the winter to retrieve the meat that had been cached from the fall hunt.”
While many of the hunting blinds at the bottom of Lake Huron are set up to attack caribou moving in both migrational directions (southeast in the autumn to rut and northwest in the spring to calve) some are V-shaped, giving the impression that they would work for movement in only one direction. Based upon which direction they are facing, scientists can determine whether they were used for fall or spring migration. In addition, some blinds are minimal, suggesting their location didn’t work, while other blinds are more extensive and updated, indicating they are in better locations and fortified to allow for more hunters.
“A number of the structures are located on high ground at the break of the crest of a hill, so that the animals coming up the hill don’t really see (the hunters) until they are upon them,” O’Shea said. “They did things that make a lot of sense to a modern hunter’s eye.”
As for the final smoking guns, such as large pieces of bone or spear or arrowheads that would remove all doubt of hunting activity on the ridge, O’Shea said large or macro bone pieces almost certainly have dissolved over time. The microbone fragments that have been found were discovered in core drilling samples. Larger pieces of bone would only be found in holes or caches within the limestone.
The spear or arrowheads are still on the agenda and will hopefully be discovered, if only so O’Shea can uncork his whiskey. 
When asked if his team has made enough discoveries to certainly prove the existence of hunting on the ridge, his answer is one you may expect of a scientist.
“We’ve gone a long way towards ‘certainly,’ but I wouldn’t say absolutely … yet,” he said.
This summer, O’Shea’s team has plans to look for additional campsites, devise better means of collecting bulk sediment samples and search for cultural debris, expand the search to natural migration choke points and expand acoustic coverage.

Thursday, April 4, 2013

A new way to look at gas consumption using rock bottom: Why simply planning to surface with 500psi isn’t the best way to manage air

This article was provided to me by James Mott of Unified Team Diving and Sea The World Scuba Center.  I met James at the Great Lakes Shipwreck Festival in which he spoke on the topic of gas management. James shared the concept of “rock bottom” in which divers determine when is the best time to begin an ascent from the deepest part of the dive to allow for a safe reserve of 500 psi when reaching the surface. Also check out the video interview I did with James at the festival.

By James Mott

Throughout the world, divers are told again and again to return to the boat with 300-500 psi in their tanks.  Understandably, most competent divers stretch their bottom time out as long as they can.  They smile as they show their pressure gauges to the dive master upon surfacing and then compare gauges with other divers in order to see who the closest one to 301psi is.  Getting the most bottom time underwater is a fun game to play with buddies and I’m not saying that divers shouldn’t use as much of their tanks as possible.  However the question becomes, “Is this the smartest way to plan gas?” What exactly is the goal of leaving some air in our tanks?  To help a buddy in need, to keep water out of our tanks, to inflate our BCD’s at the surface?  Many divers use the 1/3’s rule, but even this plan has numerous flaws.  So where do we start?  Is there a plan that works for deep-diving technical divers and shallow-water recreational divers alike?  What is wrong with the idea of surfacing with a safe amount of gas, like 500psi?
The answer to the 500psi problem is that being on the surface at the end of the dive with 500psi does not answer the more important question for scuba divers, which is, “When do I have to leave the bottom?  If we have an emergency and we need to share air, “How much air will I need to bring me and my buddy to the surface safely?  This is the question that should start all gas planning.
Doing It Right (DIR) education teaches the unified team to plan for the worst possible emergency before the dive starts.  We always ask the question, “What happens if at the worst possible moment, the deepest part of the dive, the furthest distance from home… my buddy runs out of air… How much gas do I need to bring both of us to the surface without any incident?”
Calculating rock bottom is easy enough to do in your head before the dive and it is taught in all entry level DIR courses.  How long will the ascent take, multiplied by two divers, then by the average depth and then by a consumption rate, equals rock bottom.
Rock bottom is calculated by adding up the time it would take to ascend from a given depth.  For example, from 60 feet, we would normally ascend at 30 feet/minute and have a three-minute safety stop.  This normal ascent would take us four minutes.  We then add one minute for the air-sharing emergency to take place and have a five-minute ascent, requiring 10 minutes of total air with two divers breathing during that 5 minute time frame.  We assume we have an elevated breathing rate of about 1 cubic foot/minute.  Our average depth during the ascent is about 30 feet or 2 ATA (atmospheric pressure one ATA is atmospheric pressure at sea level) where we consume gas at twice the surface rate.

5 minutes X 2 divers X 1 cfm X 2 ATA = 20 cubic feet of gas
20 cf of gas on an AL 80 is about 750 psi.
Rock Bottom for 60 FSW on an AL80 is 750 or for most gauges, 800 psi.

Rock Bottom for 100FSW on an AL 80 is 1600psi.  (Math is not provided but can be, just ask.)
Once rock bottom is determined, the remainder of the useable gas is then divided into a logical plan.  Maybe it is a drift dive on a Caribbean reef where we can use everything. Maybe we are diving on a shipwreck in the Great Lakes and need to get back to the mooring line, or we might be doing a penetration on this shipwreck where we will need enough gas to get out of the wreck plus enough to get to the surface.  Different dives will require different gas plans, but rock bottom must always be accounted for, before the gas plan is made.  DIR education teaches the unified team to plan their gas in accordance for the specific dive, so that each diver can get the most fun possible out of their diving and still be safe.
Being at depth below rock bottom is irresponsible and will not give us enough air to safely ascend.  The only emergency underwater is running out of gas, everything else is just an inconvenience.  Once the out of gas diver is breathing again, we move from emergency to management.  Just because someone ran out of air, does not mean that we rush to the surface, exceed safe ascent rates, skip safety/deco stops, or anything else we know about safe diving protocols.  The only option is to remain calm, think, communicate and finish the dive.
For more information about rock bottom or other gas management options, contact me at or or Sea The World Scuba Center in Farmington Hills at 248-478-6400.