Waters of Lake Michigan are a treasure trove of sunken wrecks

Roger Rice says the Bermuda Triangle, that polygon in the western Atlantic reputed to occasionally gobble up ships and aircraft, "has got nothin'" over the storm-battered waters off Wisconsin's Door Peninsula.

"Lake Michigan was a nautical superhighway for schooners and freighters in the 1800s and early 1900s, and a lot of them (hundreds, in fact) went down on the shoals off Door County, at Death's Door on the tip of the peninsula and over in Green Bay," said Rice, a veteran scuba diver.
And while the boats and aircraft that (supposedly) went down in the Bermuda Triangle have never been found, divers can explore at least three dozen ships off the Door Peninsula. Some are in relatively shallow water, so snorkelers can get an easy look; others are more than 100 feet down, requiring scuba tanks and training.

Rice, 69, lives at the tip of the peninsula in Gills Rock, Wis. He got his scuba certification eight years ago, after atrip to visit his son in Hawaii.

"It looked like so much fun that I had to try it, and I was a little peeved I couldn't dive with him because I didn't have my license," said Rice, who has logged more than 300 (and counting) dives since then off the Door and in California. He has no plans to slow down.

"There are wrecks out there all over the place," said Rice, whom I met while diving on the Frank O'Connor last summer. The O'Connor, a 300-foot wooden steamship, sank in 65 feet of water several miles off the Cana Island lighthouse. It was launched in 1892 and went down in 1919 after a fire.
"And really, the boats are what make diving interesting, because the bottom of the lake is so flat," he said. "It is really great to explore those old ships."

As we sped out to the wreck on a dive boat piloted by Jake Gransee, Rice said O'Connor is one of his favorite wrecks because its two large boilers and a 12-foot propeller remain intact.

"The thing burned and went straight down," he said. "So the old steam engine is just sitting there on the bottom."

Some 30 minutes later, I was geared up in a hefty wetsuit to keep out the Lake Michigan chill (it was about 50 degrees at 65 feet) and moving slowly down a buoy line toward the ship.

Just as Rice promised, the big propeller was still standing, connected to the steam engine. Unfortunately, the wooden sides of the boat had collapsed over the years and lay spread out on the bottom. Pieces of shiny coal used to fire the boilers nearly 90 years ago were scattered nearby.

The O'Connor was constructed by shipbuilder James Davidson, who built freighters in the late 1800s, when sailing was giving way to steamships. Davidson constructed his bulk carriers of wood rather than steel to save money. But they were fire traps and nearly all ended up burning.

As Gransee and I swam along the ship for the next 30 minutes, we could see layers of zebra and quagga mussels covering nearly every section of exposed wood and metal. Invaders from the Caspian and Black seas, these filter feeders are thought to have been brought to this country as ballast from tankers.

Since their colonization of the Great Lakes in the early 1990s, they have covered the undersides of docks, boats, anchors and spread into nearby streams. Widely despised, they can grow so densely that they block pipelines and clog water intakes of municipal water supplies and power plants.

But — for divers, anyway — they have an upside. Because they are filter feeders, they have greatly improved the visibility in the Great Lakes. The change has been dramatic, said Gransee, 38, who began diving when he was 14.

There are billions of these mussels in the Great Lakes, and studies show that they can filter roughly a quart of water a day.

"When I first dove on the O'Connor back in 1994, it was great to have 30-foot visibility, and 40 feet was considered phenomenal," he said. "Now it's not unusual to be able to see 100 feet, and it's a bad day when you can't see at least 50 feet. That's a huge change in less than 20 years."

Gransee, who grew up in Baileys Harbor on the Lake Michigan side of the Peninsula, said he began snorkeling around age 10 with a buddy.

"We went to a dive shop up in Gills Rock to get some gear, and the owner drew us a map of some wrecks in shallow water of around 12 feet in Baileys Harbor," he recalled. "I forget the name of the boats, but after that, we were hooked."

A self-described history buff, Gransee said he enjoys researching the wrecks he's visited and imagining what the conditions were like when the ships went down in storms.

"I also like introducing people to wrecks they haven't seen before," added Gransee, who dubbed his dive charter operation "Dark Side" after the 1973 Pink Floyd album "Dark Side of the Moon."
Gransee said he often takes divers to the O'Connor and then returns to the warmer and shallower waters of Baileys Harbor to examine the Emeline, a 111-foot-long schooner that sank in 1896 in less than 20 feet of water.

"It's a nice wreck for beginners to explore, and the water is considerably warmer than down where the O'Connor is located, where it can drop into the 40s," he said.

Gransee said he and his diving friends are always looking for new wrecks.

"There's a lot out there that hasn't been discovered," said Gransee, who uses sonar to map possible dive sites. He was planning to purchase a 'side scan" unit, which he said will "literally paint a picture of the bottom and really tell us what's down there."

"It would be great if we could find a new wreck in the 100- to 120-foot depth range," he mused. "That would really stimulate interest in diving up here again. It was more popular in the past. And way back in 1969, National Geographic did a big story on Door County and devoted a whole section to wreck diving."

In the meantime, he's content to lead customers to lakeside wrecks that start just a few miles south of Baileys Harbor and include the Ocean Wave, a scow schooner that sank in 110 feet of water in 1869.
And he can go 20 miles north to the infamous Death's Door, where three wrecks off Pilot Island went down so close together that they are touching. He also dives sunken ships on the Green Bay side of the peninsula and can even head north to islands off Michigan's Upper Peninsula.

If you enjoyed this blog, you will enjoy reading Ross Richardson's new book "Search for the the Westmoreland"

Thanks to the St Louis Dispatch

Kathy Dowsett

www.kirkscubagear.com

Air Breaks… what are they, and do people take them for the wrong reason?

Thanks to doppler and his Tech Diving Blog

I find the concept of taking air breaks to manage oxygen toxicity while decompressing comparable to using a paper towel to mop up an incoming tide at the beach. Or put another way, air breaks in this context are about as useful as ashtrays on a motorcycle.

Allow me to explain. I believe oxygen toxicity is one of the biggest risks to recreational divers, especially technical divers, but air-breaks as commonly described and executed, are no substitute for proper CNS planning… and are useless as a CNS management tool in any event.

The first time I remember hearing the term air-breaks was in a conversation with a hyperbaric doctor over a bottle of wine and a grilled fish supper some years back. The context was a discussion about the practice of getting hyperbaric chamber patients on air after 20-minute spells breathing pure oxygen at a “dry depth” of 18 metres (60 feet). Of course, this therapy – part of the procedures called for in the US Navy Diving Manual – delivers an oxygen partial pressure of 2.8 bar, well in excess of the 1.6 bar recommended as a maximum for recreational divers… technical or otherwise. I have no clue how or who decided that this term was the right one to use to describe the practice of switching to a low-oxygen content gas after breathing oxygen during staged decompression stops in the water. Nor can I fathom what it can possibly have to do with managing central nervous system (or pulmonary toxicity, gods forbid) while recreational diving.

Oxygen toxicity is a condition resulting from the harmful effects of breathing oxygen at elevated partial pressures. The most serious form of oxygen toxicity has the potential to affect a diver’s central nervous system and is a result of breathing very high-partial pressures (more than one bar or atmosphere) for a relatively short period of time (less than a few minutes at extreme levels). This type of toxicity may result in a clonic-tonic seizure; which in the water usually means death by embolism or drowning. Historically, this central nervous system condition was called the Paul Bert effect. The less problematic whole-body or pulmonary condition – a function of breathing lower partial pressures (less than one bar) over much longer periods – goes under the name the Lorrain Smith Effect, after the researchers who pioneered its discovery and description in the late 19th century.

I have heard and read that divers manage both Paul Bert and even Lorrain Smith effects by taking a short “air-break” during moderately long decompressions. The typical scenario is this: A diver conducts a deep or deepish dive which earns her a lengthy series of staged decompression stops on her way back to the surface. She finishes her dive by breathing pure oxygen at 6 metres on up. In this scenario, the decompression schedule requires the diver to breathe oxygen for around 20 minutes. There are a pile of variations on this theme, but the common thread is a fair amount of time breathing a gas that is delivering around 1.6 bar of oxygen… by the way, the NOAA limit for exposure to 1.6 bar of oxygen for a diver is 45 minutes, so this type of exposure does load a diver with the potential for a CNS incident… there is no argument there.

The “air-break” myth goes something like this. At some point during her spell breathing pure oxygen – sometimes at the end and sometime mid-stream – the diver will “RESET” her CNS “clock” by switching from breathing oxygen to breathing bottom mix, air, a less oxygen-rich nitrox (typically the mix she was breathing during her ascent to her final stops). Let’s illustrate the air-break protocol with a dive profile calling for a final decompression stop for 21 minutes at six metres or 20 feet. In this example, the diver might use oxygen for ten minutes, and then switch to say an EAN50 for five minutes, and finally switch back to oxygen for eleven minutes to finish up their deco. Typically, as in this example, the time spent on an “air-break” is not credited against the decompression obligation.

What I have yet to hear fully explained is how a five-minute break from breathing pure O2 resets a diver’s CNS loading during this procedure. Actually, you may also read postings from divers who rely on the same technique to manage Lorrain Smith effect, which shows an even greater misinterpretation of the mechanism behind the syndrome*.

OK, let’s take a step back and turn on the logic filter. According to NOAA – the folks who literally set the standards for nitrox use in the recreational dive community – a period of 20 minutes breathing oxygen at 6 metres – a practice that delivers a partial pressure or oxygen depth of around 1.6 bar/ata – has a corresponding time limit of 45 minutes. When we calculate the CNS loading for a dive, we are taught to account for the CNS loading for ALL phases of the dive. That’s to say, every minute spent breathing elevated levels of oxygen. Let’s ignore whatever came before during our example dive, and let us just focus on what happens at six metres or 20 feet. In a nutshell: The diver has to account for 20 minutes on pure oxygen. The NOAA tables don’t give a rat’s behind whether those 20 minutes are accumulated in one lump or two… or three or four. Twenty minutes is 20 minutes and uses up about 44-45 percent of the total allowable time regardless! The five minutes breathing another gas – in our example we can say she used EAN50 delivering an oxygen partial pressure of about 0.8 bar – simply adds a little to the total CNS loading, albeit a very tiny about (less than one percent). There is nothing in the NOAA dive manual or any of Hamilton’s published work that tells us anything different.

Now, to set the record straight, faced with the situation outlined above and breathing pure oxygen for that long, the chances are that I would take an air-break and recommend taking one to my team-mates; however, it has NOTHING to do with CNS but rather to help optimize off-gassing.

Oxygen is a vasoconstrictor – it causes some blood vessels to shut or partially shut – which may have some effect on general perfusion levels. This does not seem like a great plan for those of us trying to eliminate dissolved inert gas.
The bottom line is this: Let’s agree to take a break from pure O2 during our deco, but let’s not confuse the issue by suggesting that doing so magically helps manage CNS toxicity. Better yet, let’s opt to employ a better option and a slightly more helpful gas. But more about that later.


* Prolonged breathing of gas with an Fio2 (Fractional Inspired Oxygen) greater than 60 kPa (0.6 bar/ata)can lead to pulmonary toxicity and eventually irreversible pulmonary fibrosis, but this takes many hours or days and does not constitute an issue for the rank and file technical diver. Most likely, the “burning” sensation and pulmonary toxicity like symptoms mentioned by technical divers breathing oxygen and oxygen-rich gas during recreational decompression is a function of breathing cold, dry air (the dew-point of oxygen in the cylinders in my fill station is marked as -40! That’s dry.) This air has the ability to dry the mucus membranes lining our lungs and bringing on something called dry-air asthma. A less far-fetched probable outcome than pulmonary toxicity.


Kathy Dowsett

www.kirkscubagear.com