Lessons Wreck Penetration

[Nasser]

Excellent thread and actually very timely.

I just returned from a tech diving trip over a few days in the Egyptian Red Sea. Been diving the entire Red Sea for about 16 years now and have dived most of the wrecks in this area... but not deep penetration wreck dives. Over the past year or so I've decided that I'm feeling ready to take it to the next level in my training, and during this trip I was very fortunate to meet a fantastic instructor with excellent qualifications and the temperament that I'm looking for. We really hit it off and also discussed my desire to move into more Advanced Wreck diving - which is one of his specialties. So it looks like this will be on the agenda this coming year - this thread couldn't have come at a better time.

Will read and re-read several times.

 

[DevonDiver]

Some more pertinent links for further reading:

Defining Wreck Diving Restrictions:
Defining Wreck Diving Restrictions

How To Evaluate a Potential Wreck Diving Course:
How To Evaluate A Wreck Diving Course

Advanced Wreck Diving Course Notes/Supplement Reading:
Advanced Wreck Diving | Techniques | Course Notes

 

[Nasser]

Some more pertinent links for further reading:

Defining Wreck Diving Restrictions:
Defining Wreck Diving Restrictions

How To Evaluate a Potential Wreck Diving Course:
How To Evaluate A Wreck Diving Course

Advanced Wreck Diving Course Notes/Supplement Reading:
Advanced Wreck Diving | Techniques | Course Notes

Excellent links...coincidentally I just came across this a couple of days ago while I was further researching the subject. Great site Andy and tons of very useful information.

At this point I'm thinking that this thread should be made a "sticky"

 

[Akimbo]

A lot of people dream of diving recently sunken ships. Fortunately, not many get the chance… or horrendous task. As cool as it sounds, there are a lot of problems.

The first thing to consider is all those messy and/or caustic fluids like fuel, hydraulic oil, acids, and even cooking oil. They leak, collect and float everywhere -- not great for a dive's gear or skin. Pearl Harbor was probably the worst case in history. Reports in Descent Into Darkness: Pearl Harbor, 1941: A Navy Diver's Memoir by Edward C. Raymer describes 6" of heavy fuel oil blanketing the entire bay and trapped by the confines of the harbor for many months.

Another huge problem is all the "stuff" floating around inside like mattresses, false overhead panels, table tops, clothing, food stores, and even bodies. Basically, if it isn't bolted or welded down it is floating around -- probably blocking exits. In an amazingly short time you can add paneling, carpeting, florescent light fixtures, non-structural partition bulkheads, the contents of cabinets and drawers, and all the overhead cables to the party.

Cable trays and brackets corrode quickly on modern vessels because they are often made from Aluminum sheet metal, which acts as a sacrificial anode when submerged. The speed is greatly increased when Copper makes contact as insulation is damaged. Then you have miles of spaghetti everywhere and an immense entanglement hazard. Electrical cables caused a well-known death on the Andrea Doria where a "Suicide Clip" was a contributing factor.

Depending on the area and if the location of the sinking was known, you have to anticipate fishing nets and monofilament line. Sports fishing boats love wrecks because of all the fish they attract.

Virtually all of these hazards are removed from purpose sunk wrecks in addition to cutting lots of access/escape holes. This video will give you an idea of all the work preparing these ships for divers.

Ex HMAS Canberra Preparation for Sinking

​

 

[Centrals]

Depending on the area and if the location of the sinking was known, you have to anticipate fishing nets and monofilament line. Sports fishing boats love wrecks because of all the fish they attract.

The fishermen are always the good source on the locality of the wreck!

 

[Akimbo]

Divers that regularly explore wrecks in low visibility would benefit from reading this thread:

Details surrounding death of USN divers +1 year ago finally released under FOIA

Low visibility that deteriorated to zero no doubt contributed to the root problem of entrapment that ultimately killed two experienced US Navy Divers. This question was asked in Post #2 and probably deserves more discussion in this context.

...How are you going to monitor your air supply if you can't see?....

I was taught Progressive Equalization by an ex-British Navy Diver while working in the North Sea around the mid-1970s. It was developed because they didn't have SPGs in the early days of open-circuit Scuba and it continued to be used because they often couldn't see their SPG.

Progressive Equalization basically boils down to keeping one of your manifolded cylinders normally shut. You breathe down the online cylinder low enough that you perceive increased breathing resistance (worst case), open the isolation valve until you hear that both cylinders are equalized, and close the isolation valve again or end the dive.

Equalizations can be used in a dive plan to trigger events. It may be "leave bottom" on a deep dive, "leave bottom on the second equalization" on a shallower dive, or can signal waypoints to turn toward the boat or beach. You can certainly accomplish the same goal with independent doubles or bailouts/ponies. The limitation with IDs is you won't have as many waypoints unless you can see your SPG and remember two switch cylinders.

Not being able to read any SPGs or computers is a gas planning consideration for wreck divers. Progressive Equalization or independent cylinders and regulators are the only viable methods I can think of in zero visibility.

 

[KeithG]

Great post which triggered a thought: wreck awareness for non wreck divers!

My belief is that many non-wreck divers repeat the mantra of "do not go in". But is that sufficient? What about "do not go under"?

As an open water vacation diver I am often tossed onto a wreck. I fully understand "penetration" is something beyond my skill level. So we stay out. But reading about the current structural condition of some well known decaying wrecks raises a few alarms for us non-wreck divers.

Several of the "wrecks" I visit present the opportunity for a "swim under". This is not hull penetration, just the ability to swim underneath a potentially unsound wreck structure. My examples are the Turks & Caicos Thunderdome & the M/V Christena in St Kitts (I could be wrong about the name & location of the second one, but it has a long boom with lots of very photogenic Tunicates on it).

Early on I naively performed swim unders. Now I am very careful to not position myself under any structure that could fall on me.

Thoughts?

 

[lowviz]

There are a lot of posts on Scubaboard about finding your way out of a wreck and avoiding stirring up silt, but not much on other factors that influence when it is safe to penetrate a compartment. ...//...

Great thread.

...//... Several of the "wrecks" I visit present the opportunity for a "swim under". This is not hull penetration, just the ability to swim underneath a potentially unsound wreck structure.

Even a sound structure may present a risk.

...//... Early on I naively performed swim unders. Now I am very careful to not position myself under any structure that could fall on me.

Having a fundamentally solo mindset, tight swim unders/throughs are something I absolutely refuse to do. Years ago I was following a diver that did a squeeze through under a vehicle in a local quarry. I watched his tank bottom pop up when he cleared, which meant that there was no chance for him to back out if the forward exit was blocked. Not for me.

...//... Thoughts?

Don't do it unless you have to.

 

[Akimbo]

...Several of the "wrecks" I visit present the opportunity for a "swim under". This is not hull penetration, just the ability to swim underneath a potentially unsound wreck structure. My examples are the Turks & Caicos Thunderdome ...

There is a small (minute?) risk of entrapment on T&C's Thunderdome -- image attached. It is in shallow and clear water with guides tracking everyone like baby hens. At least someone could relay spare cylinders to you until they could get you out... assuming a crush injury didn't make it unnecessary. My "estimate" of the structural integrity is that it is pretty sound, for now.

However, if my estimate was wrong I would be just as trapped or dead as a diver that just received their OW card. We all have to make risk-reward judgments and pay the consequences when wrong. It is human nature to want to do stuff that looks fun, even if there is an element of danger. Just look at our sport! We will often take chances that we wouldn't ask others to take. I suppose that is the essence of that Master Diver's wisdom which sticks with me to this day.

... Then he says "OK, now would you send your brother in there who is expecting his first child?" ...

Just ask yourself that question whenever you are deciding "Is it safe in there"?

 

[Akimbo]

You don't have to be a structural engineer or marine surveyor to conclude that this is a good candidate for a collapse. Are you sure you want to go in there?