Silt Out - Wreck Danger! A graphic video demonstration.

[fjpatrum]

Thanks for a great thread, DevonDiver. I just finished arguing my way through the "Dangerous Psychology-Diving beyond our training" thread (spun in part by the thread CT-Rich indicated, I think) and this really puts another spin on the same subject.

Not only diving beyond our training, but diving in unexpected conditions that should have been reasonably expected. Often, even our official training doesn't sufficiently prepare us for these unexpected conditions, which is what several people were trying to express, so how can anyone possibly really comprehend them without good training?

This video helps me consider my views further about how much you can really comprehend the risk without some controlled exposure to those risks during real dives.

Thank you.

 

[o2dependant]

Thanks for this thread. And not wanting to start another thread I will use this one to thank everyone who goes to the effort of contributing some very informative discussion, news articles and now even educational videos.( i say now. For me its now!!)

Reading through the accident threads and some safety advice has really given me a lot to think about. I have to admit untill now I have not concearned myself enough with some of the dangers I may encounter underwater. I will never dive beyond what I feel is my limitations. thats to say will I go in a cave? Not without the training, will I go through a hole in the wall that I can clearly see the other side? Yes.

I have a question about a silt out in a confined space without current. Out of pure curiosity, How long would it take to settle? Are we talking hours or days?

 

[ianr33]

Also, not sure why you imagine a full-size doorway enforces a single-file exit? The 'rule' is that divers need to be able to exit whilst sharing air (assuming no long hose). They can do that through a door. Side-by-side is one technique. Piggy-back is another. I teach both. Piggy-back is especially important... as doorways tend to feature highly in most wreck penetrations...


They were fully equipped as per PADI standards, including lights + backups...along with safety reels. Not that a light would make a gnat's chuff of a difference in a silt-out...

Sure I'm preaching to the choir here but I have a couple of questions.
1) if the line is in a corner of the doorway, how are divers supposed to share air with a short hose AND each maintain contact with the line? Seems to me the only realistic way to exit on a line, in zero viz, is one behind the other,which requires a long hose.

2)If you have a OW type pistol grip, light then in an OOA situation you will have one hand holding the light,one hand holding the line and one hand holding the donated reg firmly in your mouth. Anyone see a problem with that?

Zero viz exits on a line are not trivial, especially as the stress level will go through the roof with inexperienced divers. Handicapping these divers with the wrong tools (short hose, pistol grip lights ) is stupid.

Given a real siltout, combined with an OOA situation, how many "Rec Wreck" divers would survive it ?

I appreciate the video. Very applicable to caves as well.

 

[DevonDiver]

I have a question about a silt out in a confined space without current. Out of pure curiosity, How long would it take to settle? Are we talking hours or days?

That's down to a number of variable factors:

1. Strength of water flow.
2. Geography.lay-out of the silted area.
3. Nature of the particulate matter raised. Silt is generally divided into 3 categories:

• Sand - anything bigger than 1/16mm
• Mud - anything between 1/256 and 1/66mm
• Clay - anything smaller then 1/256 mm and generally measured by settling factor. Some sediments hold electromagnetic charge and will bounce off each other in suspension for infinity.

In the case of wrecks (rather than caves) you also need to account for 'artificial' (non-organic) silt materials:

• Rust - of vary size/suspension dislodged or peculated from the wreck structure.
• Liquids (POL) - oil, fuel etc that can be released into the water.
• Other materials - degraded plastics, rotted wooden structures, paper etc etc

For reference, the silt-out demonstrated in my video took several hours to settle/wash-away. Within 5 minutes, the silt billowing out of the doorways and port-holes had significantly degraded visibility across the entire wreck (it's a small Landing Craft Tank (LCT) Mk6).

1) if the line is in a corner of the doorway, how are divers supposed to share air with a short hose AND each maintain contact with the line? Seems to me the only realistic way to exit on a line, in zero viz, is one behind the other,which requires a long hose.

You can piggy back. A doorway should permit two divers to pass, whether vertically, horizontally or diagonally aligned. The divers need to (train) to orientate themselves to pass through that space..



but this is always better..

2)If you have a OW type pistol grip, light then in an OOA situation you will have one hand holding the light,one hand holding the line and one hand holding the donated reg firmly in your mouth. Anyone see a problem with that?

IMHO, pistol grip-type torches are not suitable for guideline work at all... which basically means all overhead environment penetration..

That said, it can be an either/or situation:

OOA alone (no silt-out) doesn't require a hand for the guideline. One hand for torch, the other for buddy or hose/reg.

OOA plus Silt-Out = One hand for guideline, one hand on buddy. You never release the guideline or your buddy. If silted out, then the torch can be stowed anyway - that's what the guideline is for...

Zero viz exits on a line are not trivial, especially as the stress level will go through the roof with inexperienced divers. Handicapping these divers with the wrong tools (short hose, pistol grip lights ) is stupid.

Add to that the typical 'entanglement rich' configurations that most/many recreational divers utilize. Danglies, projecting hoses... make zero viz exits a true nightmare. Short hose and pistol grips are the least of it..

Given a real siltout, combined with an OOA situation, how many "Rec Wreck" divers would survive it ?

Who can say? The important issue is that such survival is the product of (1) LUCK and (2) IMPROVISATION.

Divers should not put themselves in situations where those factors determine live-or-die outcomes...

 

[TSandM]

There really is no teacher like experience, as long as you survive the experience.

When I took my Cave 1 class, the instructor took issue with the way I had tied the loops in my pockets, and claimed that if I kept them that way, the clips would migrate out of the pockets and get tangled in the line. I thought he was being ridiculously nitpicky, and the loops were difficult to undo, so I left them the way they were.

Danged if, within the first few dives after class, I didn't have to disentangle myself from those clips, doing exactly what Danny said they were going to do. I went ahead and picked the knots apart, and retied the loops the way he wanted them done.

You can tell people it's important to streamline their gear until you're blue in the face, but they won't be anywhere near as convinced as they will be, once they try to do a blind exit and find themselves getting hooked up on big loops of hoses and dangling consoles and lights.

 

[Mr.X]

Fun video and thread! Have been in this situation many a time on commercial jobs. Not fun. And yes, experience teaches you a lot.

I will say rebreathers help a lot in not stirring up overhead muck. As well as honed technique. One thing I would add is to assign purpose and ask "why am I going in there in the first place." Certainly wasn't worth it for the Andrea Doria guys going after plates during the 90's.

X

 

[ianr33]

IMHO, pistol grip-type torches are not suitable for guideline work at all... which basically means all overhead environment penetration..

Does PADI agree with you? Serious question: Are Pistol Grip lights within standards for any PADI (or any other agency) overhead course?

 

[nimoh]

Does PADI agree with you? Serious question: Are Pistol Grip lights within standards for any PADI (or any other agency) overhead course?

According to PADI's website, there are two kinds of lights and since pistol grip lights, are not canister lights, I assume PADI classifies them as flashlights suitable for night dives, but not preferable as primary lights for wreck and cave diving.

Based on this, I would infer that PADI does agree.

[h=3]Styles[/h]There are two basic styles of dive lights, with different options in rechargeable or disposable batteries, and the type of bulb it uses.

• Flashlights – These range from small, compact lights used during the day or as backups for night, wreck and cave diving, to large lantern-style lights that are primary light sources when diving in the dark.
• Canister lights – Used primarily by wreck and cave divers, canister lights supply a compact light via wire with power from a battery in a canister carried on your waist. Canister lights are usually much brighter (though this is changing as lighting technology advances make smaller lights more powerful), so this makes carrying their larger batteries more convenient.

 

[DevonDiver]

According to PADI's website,...I would infer that PADI does agree.

Styles

There are two basic styles of dive lights, with different options in rechargeable or disposable batteries, and the type of bulb it uses.

• Flashlights – These range from small, compact lights used during the day or as backups for night, wreck and cave diving, to large lantern-style lights that are primary light sources when diving in the dark.
• Canister lights – Used primarily by wreck and cave divers, canister lights supply a compact light via wire with power from a battery in a canister carried on your waist. Canister lights are usually much brighter (though this is changing as lighting technology advances make smaller lights more powerful), so this makes carrying their larger batteries more convenient.

Where's the quote from?

 

[recardomaurice12]

I think this such demonstration is too risky, hope you guys could keep the best practices