DogDiver
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Wreck v Cave Diving
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USFpsychDiver
Contributor
I dive cave, and have never dove anything but an occasional 'tourist' wreck. While there are plenty of deep caves and shallow wrecks, it seems like most cave divers spend most of their time in 40 - 100' depths (roughly), while the interesting wrecks are deeper. Deep has always struck me, from my place of general ignorance (ANDP training), as more challenging than overhead. I can have any manner of problems way back in a 40' deep cave and even losing half my gas still have an hour or so to solve the problem and get out. At 180' I don't have that luxury. So I'm full cave with 100+ cave dives, stage & deco, by not means an expert but a novice with some experience, and I'm no way prepared to dive a deep wreck; better prepared than an OW diver, but I'd still want some training and a good mentor to start actual technical penetration wreck diving.
DevonDiver
N/A
I'm currently teaching a technical wreck course to a full cave qualified diver (taught by Pascal Bernabe).... so I'll ask him to contribute his opinions to this thread.
In personal conversation, he's expressed that he finds wreck penetrations more demanding and carrying more risk than cave. He's seen, first hand, a partial collapse in a wreck (thought I was dead for a few seconds!), done some very tight restrictions and seen plenty of silt... He said the wreck environment was more confusing and disorientating in general. There was also more risk of equipment damage from rusted metal, rather than abrasion in caves (although he encountered sharp rock formations cave diving in France).
The exception is that cave diving places more stress on the gas management plan because of the duration/distances involved. In contrast, wreck penetrations can be shorter duration/distance....and typically, have multiple options for exit or early abort.
On a personal note; it's important to recognize that wrecks vary in character and demand.... just as caves vary in complexity and challenge. This can make it hard for individuals to make a comparison unless they've got a wide enough experience of different wrecks/caves to understand the general aspects that differentiate those diving environments.
In personal conversation, he's expressed that he finds wreck penetrations more demanding and carrying more risk than cave. He's seen, first hand, a partial collapse in a wreck (thought I was dead for a few seconds!), done some very tight restrictions and seen plenty of silt... He said the wreck environment was more confusing and disorientating in general. There was also more risk of equipment damage from rusted metal, rather than abrasion in caves (although he encountered sharp rock formations cave diving in France).
The exception is that cave diving places more stress on the gas management plan because of the duration/distances involved. In contrast, wreck penetrations can be shorter duration/distance....and typically, have multiple options for exit or early abort.
On a personal note; it's important to recognize that wrecks vary in character and demand.... just as caves vary in complexity and challenge. This can make it hard for individuals to make a comparison unless they've got a wide enough experience of different wrecks/caves to understand the general aspects that differentiate those diving environments.
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I wouldn't say that the more interesting wrecks are deeper, it's just that there are many deeper wrecks that are less frequented and thus often more highly prized by wreck divers.
They are less frequented because they are deeper and at depth on open circuit you're using gas at a much higher rate and have much less time to solve problems.
However, the same OC gas limitations occur on a deep cave dive. The difference is that in a cave, rather than just having a greater deco obligation due to the delay, and less gas to address the added deco due to the delay, you also still have the greater distance to the exit, which adds even more deco obligation with an even more limited gas supply.
The major advantage in that situation is that you don't have to carry all your gas with you for the entire dive.
Still, the desireability for more time to resolve problems, more efficient decompression, and reduced gas requirements on long, deep cave dives is why we made the move to CCR for cave diving.
They are less frequented because they are deeper and at depth on open circuit you're using gas at a much higher rate and have much less time to solve problems.
However, the same OC gas limitations occur on a deep cave dive. The difference is that in a cave, rather than just having a greater deco obligation due to the delay, and less gas to address the added deco due to the delay, you also still have the greater distance to the exit, which adds even more deco obligation with an even more limited gas supply.
The major advantage in that situation is that you don't have to carry all your gas with you for the entire dive.
Still, the desireability for more time to resolve problems, more efficient decompression, and reduced gas requirements on long, deep cave dives is why we made the move to CCR for cave diving.
beester
Contributor
Heya USFPsych...I'm as you full technical cave (C2) with about 100 post course cavedives...about 1 third of my cavedives is deeper than 30m/100ft (those deeper ones on average 50m/145ft).
Depth, whether this is on a deep wreck or in a deep part of a cave is a problem all in itself. Just like DA Aquamaster already mentioned. Looking at how fast a 80cuft bottom stage goes at 60m tells you enough. Next compounding the problem is that at depth you need to start to make those necessary gasswitches which will make the taskloading while dealing with a problem even higher.
The normal strategy of solving problems at depth is to stabilize the problem and ascend while managing the issue. You want to get out of this deep danger zone asap both from gas management and deco point of view. Within most wrecks this is possible within 5-10 minutes at most. In caves not always so.
Last summer I dived on a WW1 german u-boot on the Sandetti bank close to Dover, England. It's located in 50m water and you can enter parts (although very very restricted). In case of a problem in 3-5 minutes at most you'll be ascending to your 21m gas switch.
Same summer I was in the French Lot region diving the "emmergence du Ressel". A cave which drops after about 400m to 48-49m... then continues to 3rd T at 900m and 51m, and then goes on and on and on. If you dive the deeper part with scooters it's already a 3 stage dive... if you do it without scooters it becomes a 4-5 stage dive (some of them pre staged... advantage of cave diving). So if you have a problem at 900m even with scooters you will only get out of the deep part after 15 minutes or 40-45 minutes swimming.... from gas management and deco perspective this same 50m overhead dive becomes much more difficult than the 50m wreck dive.
The time needed to manage the problem and be able to start your ascend makes all the difference.
Same discussion can be made for navigation... the layout of a conventional ww2 or later cargo ship is not that difficult, however navigating a warship (small corridors, small spaces, very crowded) definitely is. Navigating a French cave is easy (just follow 1 main line with maybe a couple of T's) but navigating mexican caves isn't...
One thing that wrecks don't have going for them in my opinion is restrictions and vis. You just have to count on some stuff grabbing you or your equipment when navigating a corridor in a wreck... you have to count on reducing vis to miniumum in a wreck... in a cave this normally is only the case if you **** up. (or it really is a cave not dived and percolation is messing vis up). I also have never accidentally (non intention) entered overhead in a cave, but in a wreck this has happened... cut in half freighter, very bad 1m vis in North sea and by accident you enter the cargo hold and enter overhead.
So just a long story to say... it's comparing apples and oranges. BUT I became a better wreckdiver by taking cave ;-)
Depth, whether this is on a deep wreck or in a deep part of a cave is a problem all in itself. Just like DA Aquamaster already mentioned. Looking at how fast a 80cuft bottom stage goes at 60m tells you enough. Next compounding the problem is that at depth you need to start to make those necessary gasswitches which will make the taskloading while dealing with a problem even higher.
The normal strategy of solving problems at depth is to stabilize the problem and ascend while managing the issue. You want to get out of this deep danger zone asap both from gas management and deco point of view. Within most wrecks this is possible within 5-10 minutes at most. In caves not always so.
Last summer I dived on a WW1 german u-boot on the Sandetti bank close to Dover, England. It's located in 50m water and you can enter parts (although very very restricted). In case of a problem in 3-5 minutes at most you'll be ascending to your 21m gas switch.
Same summer I was in the French Lot region diving the "emmergence du Ressel". A cave which drops after about 400m to 48-49m... then continues to 3rd T at 900m and 51m, and then goes on and on and on. If you dive the deeper part with scooters it's already a 3 stage dive... if you do it without scooters it becomes a 4-5 stage dive (some of them pre staged... advantage of cave diving). So if you have a problem at 900m even with scooters you will only get out of the deep part after 15 minutes or 40-45 minutes swimming.... from gas management and deco perspective this same 50m overhead dive becomes much more difficult than the 50m wreck dive.
The time needed to manage the problem and be able to start your ascend makes all the difference.
Same discussion can be made for navigation... the layout of a conventional ww2 or later cargo ship is not that difficult, however navigating a warship (small corridors, small spaces, very crowded) definitely is. Navigating a French cave is easy (just follow 1 main line with maybe a couple of T's) but navigating mexican caves isn't...
One thing that wrecks don't have going for them in my opinion is restrictions and vis. You just have to count on some stuff grabbing you or your equipment when navigating a corridor in a wreck... you have to count on reducing vis to miniumum in a wreck... in a cave this normally is only the case if you **** up. (or it really is a cave not dived and percolation is messing vis up). I also have never accidentally (non intention) entered overhead in a cave, but in a wreck this has happened... cut in half freighter, very bad 1m vis in North sea and by accident you enter the cargo hold and enter overhead.
So just a long story to say... it's comparing apples and oranges. BUT I became a better wreckdiver by taking cave ;-)
ajduplessis
Contributor
a different spin on things....
I am cave certified and dive OC. Wreck diving for me is a natural extension from cave, HOWEVER many wrecks are not OC friendly (rust dust). OC bubbles will immediately and continuously disturb this "dust" from ceilings etc and dramatically reduce viability. Serious wreckers will generally not even consider OC divers.
Yes, I know not all wrecks are rust buckets.
Yes,I know silt can cause the same issue for OC in certain caves.
My $0.02 for consideration.
I am cave certified and dive OC. Wreck diving for me is a natural extension from cave, HOWEVER many wrecks are not OC friendly (rust dust). OC bubbles will immediately and continuously disturb this "dust" from ceilings etc and dramatically reduce viability. Serious wreckers will generally not even consider OC divers.
Yes, I know not all wrecks are rust buckets.
Yes,I know silt can cause the same issue for OC in certain caves.
My $0.02 for consideration.
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I agree. One of the other motivations for going to side mount CCR was the reality that we were increasingly diving small, rarely traveled passages with old line buried in silt, and silt percolating off the walls and ceiling, leaving poor visibility going in (for the trailing diver in the team), and no visibility going out for either diver in the team.
The CCR reduces the percolation, but more importantly it provides more time to exit, since the viz will still usually be near zero in many spots given passage size and the line issues that have to be addressed on the way in.
Another benefit is the ability to economically dive with some helium in the mix in circumstances where you might otherwise accept an END in the 100-130' range. If you're only using 7-8 cu ft of diluent on a long dive, the cost of trimix isn't a factor.
Whether you are diving wreck or cave, a CCR solves a lot of issues.
However, in a cave environment, the bailout gas planning becomes even more critical given the longer distances needed to exit, and the increased deco obligation you'll pick up OC versus CCR. Consequently, to an even greater extent than in wreck diving you'll want to resolve the issue and go back on the loop rather than just bailing out to OC.
The flip side however is that in cave diving you can plant the bailout gas in the cave if you're planning several dives and limit the amount of bailout you have to carry with you.
And I hate to be the spoil sport, because while I am going to do a Cavern course to round out my basic wreck training before finishing Tec and then TecWreck... the reality is that in 10 years, of the hundreds of sites available now for penetration diving, most will have become so unsafe they can no longer be dived except from the outside.
There are older wrecks out there, but those that originated from WWII suffer from the fact that most of them became wrecks by losing structural integrity to the point they sank. What I am saying is that from everything I have read, and people I've talked to, the wrecks at Chuuk Lagoon, Coron, and even Subic along with nearly all of the NE US wrecks that were lost in WWII are becoming structurally unsafe.
So in my mind, the caves will always be there for those who are interested. But the wrecks have a limited shelf life (so do I), so I'll train to experience them first.
DevonDiver
N/A
It really depends on the wreck. Many WWII vessels were mass produced and not built to last. The armored warships are much more long-lasting.
Here in Subic, the USS New York armored cruiser (ACR-2) will be around for generations. It's rock solid. In contrast, our frequently dived Landing Ship Tank (LST) is perishing at an observable rate - it won't be safe for any penetrations within a few years.
I had a 10ft by 4ft section of plate detach from the USS Majaba (El Capitan) boiler room wall (wreck is on its side) and fall on my leg last week. No contact with it - must have just been effected by bubbles. My technical wreck student thought I was dead for a few seconds - after disappearing in an immense cloud of silt and hearing a large 'boom'. I was lucky and extracted myself. Until recently, the Majaba had been considered very stable.
Actually, the deeper wrecks are generally in better condition as they are more protected from the ravages of water conditions; especially storms.
But further to your point... less frequented also means less stripped of interesting artifacts.
The real prizes are 'virgin' wrecks....and that usually means deep wrecks. I am sure cavers understand the attraction of going where nobody has explored before.
In my limited experience of viewing wrecks from the outside I've seen a few disintegrated ones (Benwood comes to mind), but have fallen prey to the illusion that wrecks are mainly static - i.e. not constantly changing. Or only changing during storms, or when no one is looking. Frankly, Devon Diver's brush with 40 sqft of steel plate dislodged by his bubbles is truly scary. I've seen rockslides and avalanches, but who thinks of steel structures (even rusted ones) just falling apart and dropping on your head? I'm glad you escaped unharmed; thanks for sharing the experience.
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