Recreational overheads, especially wrecks

[TrimixToo]

Nice job. I'm going to forward this to some recreational family members!

 

[Steve_C]

A local quarry has an upright school bus that has been stripped of all seats. So many folks go through that there is zero silt even though the quarry has a silt floor. Both side doors and the front door are removed. I have been with OW divers who did not want to enter since it was an overhead environment. I respected their desire to not go in of course but it shows the extreme mindset of some students.

 

[RTC'83]

Just finished the wreck padi course this w/e. My instructor was well trained and very experience tec diver. We learned limited penetration within the light zone. We did land and water reel work, practice 3 basic kicks to minimize silt-outs. Light comunication and secondary lights. Worked on our sac rates, and learned about gas management rule of 1/3. We also practiced out of gas scenarios that were more intense than OW. Never permit overconfidence to take over common sense.
Overall a great class, my take away practice the skills and if you are really interested in penetration wreck diving you better be trained as a Tec Diver.

 

[kotik]

I think it's a good article. In my opinion it's not written in a way to encourage someone who wouldn't be likely to get themselves into trouble on their own. But someone who takes the time to read it might become aware of some things to think about that they might not otherwise.

I do believe that people are capable of exercising some judgment, and knowledge is power. People that want to will use knowledge to their benefit. There will always be some others who will go ahead and do what they feel like no matter how well it's explained to be a stupid idea. They do that in spite of the available information though, not because of it.

There's no point in sweeping a subject under the rug and pretending it's not there if it plainly is. To me (IOW, no great mind) this subject is okay getting a little air and sunlight.

 

[drrich2]

Glad to see this, BoulderJohn; thanks for writing and congratulations on getting it officially published. I'm old enough to not expect to see all the loose ends/inconsistencies of Life 'tied off' and provide good closure, but this one bothered me.

A local quarry has an upright school bus that has been stripped of all seats. So many folks go through that there is zero silt even though the quarry has a silt floor. Both side doors and the front door are removed. I have been with OW divers who did not want to enter since it was an overhead environment. I respected their desire to not go in of course but it shows the extreme mindset of some students.

And that was my mindset for quite awhile. I got certified, drank the 'no overhead diving without pertinent additional training/certification - period' Koolaid, then did Caribbean 'dive tourist' trips where guides often led vacationing recreational divers on swim-throughs. I'm bigger around than many so fear of getting stuck was a factor, but still, it raised the question...if what I took to be one of PADI's strong recommended prohibitions against an allegedly dangerous activity was exaggerated to the point of being silly and routinely ignored in real world practice, then what about the others?

Would it be that big a deal to violate NDL a few minutes? Is dropping to 145 feet so dangerous vs. strict observance of a 130 foot depth limit? Is venturing a few yards into a cavern with a flash light to look around deadly?

Not everybody researches such topics on Scuba Board or other forums, or takes pertinent formal course work. Some observe others with a 'monkey see, monkey do' attitude.

Richard.

 

[johndiver999]

Without lots of experience, I don't know that divers can judge what a safe swim through is. I like that the article says "silt free" but I've seen stuff that looked pretty benign turn to absolute crap in an instant. How many divers have you seen where in a moment of chaos their solution was to bolt to the surface?

T.bix was in the Ginnie Ballroom about 5 years ago when farther in the system behind the grate was a collapse, zeroing vis in the ballroom almost instantly. Fortunately he and his sons were there because the lady who was an open water diver had panicked and bolted to the ceiling.

Sure it's a fluke and almost never happens, but I've seen a few similar type events on the Spiegel Grove.

I think it is a great write up. But I agree with the concern above.. the advice that you don't go in if there is silt.. that can be unknowable to a new diver in a new location. Almost any wreck or structure will have some silt on the bottom - it may be hard to judge what depth or composition of sediment is a potential problem.

Also, another potential issue is that a wreck that is rarely visited may present a huge problem when rust starts raining down from above. If divers frequent the wreck, then the ceiling is well scrubbed by bubbles, but if it is an area that gets little traffic, it can be very clear going in, and if the diver doesn't turn around and instead keeps moving forward, they might be very surprised by the terrible vis that is following them, even though they are carefully staying off the bottom and hugging the ceiling as much as is practical.

They might get to their presumed exit, only to find that it is smaller than it looked and when they turn around, they can see very little and have no chance of seeing light from the original entrance due to the clouds of rust raining down from the ceiling. Rust coming down can be unavoidable and is different than using good technique to avoid stiring the sediment on the floor of the overhead.

The premise of the advice seems to be that the diver is making a one-way traverse underneath an overhead, but if the presumed exit is not as envisioned - problems can arise.

 

[Steve_C]

One of our favorite wrecks is the Hyde. Sunk many years ago deliberately. It is upright. There is a large room on the stern with the back wall curved and originally full of large picture windows which are now gone. Originally there was an open hall that went back through a roofed over open work area and then out a large door into the top of a large open hold that went down to sand level. (It was a hopper dredge). Now heavily covered in coral. I have never seen silt a problem nor the rust rain. However, each year it is different as the time and hurricanes have taken their toll on the middle room and its roof. I have learned to check the passage from the hold area. Some years I dive it. Some years I don't. It went from you could see the light once you entered the passage to caved in and I would not do it to open except for one hanging cable you had to look out for to now very open and you can see the hold light from the back room. So I check it out from the hold end first to make sure it is still an easy meander (fat diver in doubles with a large pony could just drift through) . It is especially nice on lower viz days since it is often loaded with fish and the viz seems better. With an instabudy I will check ahead that if I decide it is go that they want to go. If it is a go, often they say later it was the highlight of the dive. The fact that you often share the back room with an adult sand tiger or two and the middle part with a school of large spade fish add to the appeal. For those who like those things there are some gold spot gobies that live at the bottom of the hold.

Point is that this is a swim through that is carefully accessed several times each year since things change and only dived by me if it is very open and buddy is in agreement and I have assessed buddy in the water and they seem competent. For the swim through we usually start at the back window and come through them. If there are sharks in there I want my buddy to see them before they go in and not come upon them while doing the swim through. Also the windows while large and easy are the greatest and only restrictions on the dive so if they have any issue there due to trim and buoyancy we can just abort the swim through.

 

[Trace Malinowski]

Divers spend their money on so many bullsh*t courses. Why not take a quality wreck penetration course from an instructor who has wreck and cave experience? There was once a time when finding the education was difficult. When I became a PDIC instructor in the 1980's, you couldn't teach wreck penetration diving until you became a cave diver. The thought was that the NSS-CDS and NACD had state of the art overhead training that would help the agency vet its instructors.

Wrecks and caves are different animals with similar stripes. With education in each readily available, why are we not encouraging divers to take a safety course that can save lives, drastically improve diving skills, and open up new adventures the diver never thought possible?

 

[boulderjohn]

if what I took to be one of PADI's strong recommended prohibitions against an allegedly dangerous activity was exaggerated to the point of being silly and routinely ignored in real world practice, then what about the others?

This was part of my discussion with PADI. When you make absolute statements about never, ever going into an overhead environment (and the current OW course manual does make such an absolute statement), you create a cognitive dissonance on the part of the student/diver. A student learns in the OW course manual that you can never enter any overhead environment without advanced training, and then the OW instructor takes the class through a short swim-through, as is allowed according to a PADI training bulletin. That student then goes to Cozumel (which is what I did for my first couple years of diving) and goes through swim-throughs on most dives. The inevitable conclusion is that the prohibition on overhead diving is pure BS and can be completely ignored. The student then has no guidance whatsoever for making future decisions, and has no idea what other rules are pure BS.

 

[boulderjohn]

Without lots of experience, I don't know that divers can judge what a safe swim through is. I like that the article says "silt free" but I've seen stuff that looked pretty benign turn to absolute crap in an instant. How many divers have you seen where in a moment of chaos their solution was to bolt to the surface?

T.bix was in the Ginnie Ballroom about 5 years ago when farther in the system behind the grate was a collapse, zeroing vis in the ballroom almost instantly. Fortunately he and his sons were there because the lady who was an open water diver had panicked and bolted to the ceiling.

Sure it's a fluke and almost never happens, but I've seen a few similar type events on the Spiegel Grove.

Of course, the ballroom in Ginnie Springs is not a swim-through, as anyone can tell from the basic definition calling for two visible exit points. The Ballroom is a cavern, which is a significantly more advanced site than a basic swim-through.

I know of several events on the Spiegel Grove, but none involving a swim-through. The events I know of came when untrained people did penetrations that clearly violated training concepts.