Tech Wreck - Opinions on staging your deco tanks for penetration?

[DevonDiver]

I'm doing some writing at the moment, and looking for a wider spectrum of perspectives on the issue of staging deco cylinders for wreck penetration.

Obviously, there's going to be some firm opinions on this and/or flexible approaches dependent on situational requirements.... and let's assume that we've all read about the Rouse's....

So, how do you approach the decision to stage deco cylinders if planning a wreck penetration?

Do you have a firm methodology/principle that you always adhere to? Always stage? Never stage? Don't do penetrations if you can't take stages along?

Do you approach the decision on the basis of functionality? Some wrecks/areas you just cannot take/fit stages into, regardless of your preference?

Do you make a decision based principally on risk? Risk of having the tank inside, versus, risk of not getting back to the tank? (many factors to account for).

I have my own opinions on this, but would love to hear your perspectives!

 

[GrimSleeper]

Has to be relative risk, in my opinion. Swimming through large spaces, minimal entanglement risk, easy entry/exit? Why leave that precious deco gas behind. But if the decos themselves become a risk (entanglement, getting yourself wedged) or are at risk (possibility of damaging a valve, reg, losing gas etc), then it makes more sense to stage them. I suspect that'll be the answer you get most.

What's possibly more interesting is HOW do you stage decos to avoid precisely the sort of disaster that hit the Rouses? Again, probably situational and dependent on dive plan, but I have a sneaky feeling that's the issue you're looking at writing about... :blinking:

 

[ianr33]

What's possibly more interesting is HOW do you stage decos to avoid precisely the sort of disaster that hit the Rouses?

A little helium is a good place to start.

 

[Splitlip]

Funny. Boulder John has a thread going about staging deco cylinders.

 

[DevonDiver]

What's possibly more interesting is HOW do you stage decos to avoid precisely the sort of disaster that hit the Rouses?

(narcosis management aside...)

Was thinking about this: the solution I came up with was to run a external (marked/arrowed) line over the wreck (covering various exit points) back to the ascent line. That'd be a goal of a pre-penetration dive. All subsequent teams would then have a reference back to the upline that could be quickly found from any point on the wreck.

I'd treat that like the perm-line in a cave - running subsequent penetration lines from it. It'd depend on the scale/situation of the wreck though... but workable with sufficient planning/communication.

If you (were forced) to egress the wreck via an alternative exit, then you'd locate and follow the external guideline back along the wreck. You'd find your penetration line along the way... recover your cylinders... then continue along the external line to the ascent line.

Again, probably situational and dependent on dive plan, but I have a sneaky feeling that's the issue you're looking at writing about... :blinking:

I just want to put together some material on use of deco cylinders during wreck penetration... very generic stuff. I like to see alternative perspectives and experiences though... as this makes any understanding more complete.

 

[waterpirate]

I think if you are team diving there has to be a firm protocol established pre-dive, if solo then it is simple risk management. I would not be a fan of running exterior lines back to ascent line, would consider that a crutch, not a tool in open water.

I do not penetrate where I can not take my bottles, however it is based on the prize. If presented with a prize that I felt was worth the risk I would stage at the exit, assuming running line inside the wreck and returning the same way, with adequate helium.
Eric

 

[DevonDiver]

I would not be a fan of running exterior lines back to ascent line, would consider that a crutch, not a tool in open water.

A crutch for what?

Bad navigational skills,... when under critical time pressure in extremely limited viz?

I never understood the reluctance to lay lines externally.... is it more than a bravado thing?

Yes, a direct ascent is always possible - and the diver should be trained, equipped and prepared to do so, if demanded. However, if the plan is to return and ascend on the line... why not ensure that you can return and ascend on the line??

 

[waterpirate]

A crutch for what?

Bad navigational skills,... when under critical time pressure in extremely limited viz?

I never understood the reluctance to lay lines externally.... is it more than a bravado thing?

After your stressed, overdue, limited vis exit on that line, are you going to go back and clean that mess up? Or are you going to reel up while stressed, overdue, limited vis, and exit?

Here in the Atlantic northeast we all have laid line and turned around to find some numbnuts following it. If you are reeling up, now you got yourself an insta buddy that follows other peoples lines???? The same goes for penetration here. The lines are never left and the tie off is allways inside the wreck away from curious eyes, see above.
Eric

 

[DevonDiver]

Eric.... were talking about 'tech wreck' here. Are your Atlantic tech divers really that likely to go blundering around on other people's lines?

 

[waterpirate]

The atlantic does not discriminate. On any given charter on the same wreck you will have the al 80 for 12 minutes crowd, some breathers, and the oc doubles crowd of which I belong. My definition of tech being a mandatory cieling. Typical protocol is breathers in first, followed by doubles, followed by al 80 folks. Most breather people and doubles folks will due one long dive to the ndl folks's two dips.
Eric