My steel doubles and wetsuit - no mix?

[rjack321]

Big-L, since you have neither drysuit, doubles of any kind, dual wing, or technical training maybe its best to sit this discussion out eh?

 

[Big-L]

Observation may not be one of your strong points but I did mention the type of equipment I own in my post. Also if you were basing your keen observation in regards to the gear I have on my profile then you're quite wrong, Sir.

I'll make an assumption of my own and say that the only reason why you wrote your post above is because you really can't think of anything else to say in reply to me other than mention the fact that my profile is incomplete, and I don't have any formal technical training. Perhaps you are the one who should be "sitting this one out", eh?

No, I don't have any formal technical training but guess what? I'm curious, logical, unhappy with status quo and I like to learn. I've read numerous books, articles, posts, been to product nights, demonstrations, happen to be fortunate enough that my better half worked at my LDS, etc... etc... etc...

I understand how a dual bladder works, I've dove on one more than once, I've used a single bladder, more than once, dual 100's, single faber 149's and I'm not going to continue in order to satisfy you with a pissing contest.

What I wrote above was very logical. It makes sence. In practice it works and can save your life.

 

[walke121]

BigL, you do realize that many tech divers dive by themselves right? You said it yourself you have no tech training so why get so offensive. I am not saying you don't know what you are talking about but a little knowledge is a very dangerous thing. People read a few books and think that completely understand all aspects of tech diving. It gets a lot of people killed in this sport.

 

[cool_hardware52]

I completely disagree. Who made this "rule of thumb" you’re talking about?

Well qualified divers and instructors who gave the subject considerable thought based on real practical experience. I'd suggest familiarizing yourself with the tenents of DIR.

First of all, the ballistic material used in the outer shell of bladders (and even the inner shell) are equal or more resilient as the material used in dry suit. Due to the continuous construction of BCD’s I actually believe that there are more fail points in a dry suit than a BCD. Inflation device, purge valves, neck and arm seals, etc…

Wings seldom fail, and when they do it's almost never because the shell or bladder failed, it's because the corrugated hose / elbow or fittings fail. Drysuit "fail" to some extent on almost every dive, but catastrophic failure, where the suit cannot trap gas is rare. Catastrophic failure of a wing or Drysuit are unlikely but still possible.

You would leave your 2nd inflator hose disconnected unless there is an emergency to make sure you don‘t accidentally put air in it. I understand that this is extremely task loading for all levels of diving but in the event of an emergency, connect the secondary inflator hose and voila!

Which is easier; Using your drysuit as redundant buoyancy in the event of an emergency i.e. push the same inflator you always use or struggling to find and connect your 2nd lp hose to your 2nd power inflator?

I'm a wetsuit diver, always will be (perhaps a dry suit one day, because I would like to learn all aspects of scuba diving), I dive with heavy steel tanks, single or doubles and/or stage bottles because I like having lots of air and a back-up if needed. If you are unable to be positively buoyant without ditch-able weight, you need a redundant buoyancy device and I would highly recommend a dual bladder regardless of your exposure suit.

Proper gear selection and total weighting goes a long way to mitigating the effects of any buoyancy failure. If the diver is negative by more than the weight of their back gas + ~2 lbs at the start of the dive they need to change tanks, or back plates etc to correct their over weighted condition.

Wetsuits + High volume negative steel tanks in the ocean is a bad idea. With 20+ lbs of back gas and a 7mm suit that can loose 20+ lbs of buoyancy at depth the potential to be 40+ lbs negative without ditchable ballast is completely unjustifiable.

Using buoyant al 80's in lieu of the negative steel cylinders will almost certainly require the use of ditchable ballast. Compared to using say 2 x PST 104's each about -4 lbs empty

Here's an example:

7 mm suit + 20 lbs with 2 x PST 104, each about -3lbs empty and -11.5 lbs full.

Tanks, empty 2x 3= -6 lbs
Bands and Manifold ~-4 lbs
Dual Regs ~-4 lbs
SS Plate ~-6lbs
and Harness

Total ballast -20 lbs

Total rig with full cylinders 20 + 16 (air or nitrox) = -36


7mm Suit + 2 x al 80's each about +4 lbs empty and -2 full

Tanks empty 2 x 4 = +8
Band and Manifold ~-4
Dual Regs ~-4
SS Plate
and Harness ~-6

Weight belt 14 lbs.

Total ballast -20 lbs

Total rig with full cylinders 20 + 12 (air or nitrox) = -32

32 - 14 (weight belt ) = 18 lbs negative with full tanks after dropping the belt.


Which is easier to deal with ? -36 lbs or -18lbs?

In the first example the diver will still be negative if they do manage to return to the surface.

In the second example the diver will be positive when they reach the surface.

Can you ever REALLY be safe enough?

Diving is not about eliminating all risk, it's about recognizing the real risks and managing them.


Tobin

 

[VooDooGasMan]

Actually Its all elementary, you take the gear you have and dive to your comfort level, even yesterday I dove a different system. I change my way almost every dive, and take them to there limits. Diving to me is not fun if you use the same gear or configuration. Also I have not had any gear ever go wrong in the water enough to create a panic or problem not solved easily.

So one can argue on ones, diving ways, but as long asyou are comfortable and do not exceed you limits, you will be fine. and personally I take no redundancey what so ever, its just more **** to go wrong. oop's I do take a big light and a little lite, but thats because I do not always change battries till they are pretty dim. Since all my dives are to the extreme depth, its dark and I go through the batteries.

As for training, or learning in books or on here, just get in the water and DIVE ON THE SAFE SIDE. Your goona die no matter what ,yet do not let diving mentally mess with you to think how or what you dive with, is going to go wrong. I wish I could die diving, but its never going to happen, I dive deep air, and love it, its simple and easy.

Happy Diving

 

[VooDooGasMan]

And mathmatically colhardware has put it to you in a very easy way of knowing the gear weight.

Happy Diving

 

[SteveAD]

Just had a bit of an out of the box thought...isn't the 20 pounds of backgas technically "ditchable weight" just freeflow the reg.

I'm in no way advocating...just a hypothetical.

 

[cool_hardware52]

Just had a bit of an out of the box thought...isn't the 20 pounds of backgas technically "ditchable weight" just freeflow the reg.

I'm in no way advocating...just a hypothetical.

Humm, dumping your back gas.

1) Takes a while, can you fin up while you do it?

2) It's *another* task. Do you need more tasks during your emergency?

3) You haven't yet made it back to the surface, i.e. you are *Underwater* something to breathe is a good thing, does dumping your backgas seem like the right move?

I'd much rather dump some ballast and keep my gas.

Tobin

 

[Big-L]

I'm a little mad at myself right now because I've been working on a reply for the last little bit and windows vista encountered an error. Figures.

Let's try this again, but simplified.

I'm not trying to pick a fight, or be offensive with anyone so let's squash the beef and talk diving.

I am quite familiar with DIR diving. I am willing to accept it as a school of thought or a method of diving but I don't see DIR as the stone rules of tech diving. Hell, it even applies to recreational diving too.

I don't claim to be a tech diver because I dive with doubles and a long hose or have read a few books, articles and the actual course curriculums for tech diving. What I do know is that i understand the logic, and within the recreational limits of diving I've practiced and used technical procedures. Tech-reational diving I suppose, no?

I also wasn't arguing that a back-up bladder was better than a drysuit by any means. I'm just saying that if you choose to dive wet, a dual bladder setup is sufficient.

Let's look at that gear configuration again:

At the surface w/ tanks Full:

7mm Suit: + 20 lbs.
2 x PST 104 full @ -11.5 lbs. = -23 lbs.
Band and Manifold ~-4
Dual Regs ~-4
AL Plate and Harness ~-2
---------------------------
Total -13 lbs. I think this is manageable. Add a breath of air in your lungs, the number is less.


At the surface w/ tanks Empty:

7mm Suit: + 20 lbs.
2 x PST 104 full @ -3 lbs. = -6 lbs.
Band and Manifold ~-4
Dual Regs ~-4
AL Plate and Harness ~-2
---------------------------
Total +4 lbs. The diver is positive. Add a breath of air in your lungs, the number is more.

For arguement sake let's remove the buoyancy you gain from the suit. Yes, you would be -40 lbs at depth. Wouldn't an empty drysuit yield the same result?

If your primary inflation device fails, switch to the secondary (Either 2nd bladder or drysuit) and call the dive. DIR divers don't take on any uneccesary risks, right?

Let's keep this clean going forward and I appologize if anyone got offended or aggitated so far.

 

[cool_hardware52]

I am quite familiar with DIR diving. I am willing to accept it as a school of thought or a method of diving but I don't see DIR as the stone rules of tech diving. Hell, it even applies to recreational diving too.

I'd recommend a review.

Let's look at that gear configuration again:

At the surface w/ tanks Full:

7mm Suit: + 20 lbs.
2 x PST 104 full @ -11.5 lbs. = -23 lbs.
Band and Manifold ~-4
Dual Regs ~-4
AL Plate and Harness ~-2
---------------------------
Total -13 lbs. I think this is manageable. Add a breath of air in your lungs, the number is less.

Lets see how long you can tread water in your swim trunks if I hand you 13 lbs of lead.

At the surface w/ tanks Empty:

7mm Suit: + 20 lbs.
2 x PST 104 full @ -3 lbs. = -6 lbs.
Band and Manifold ~-4
Dual Regs ~-4
AL Plate and Harness ~-2
---------------------------
Total +4 lbs. The diver is positive. Add a breath of air in your lungs, the number is more.

Your diver is underweighted.

For arguement sake let's remove the buoyancy you gain from the suit. Yes, you would be -40 lbs at depth. Wouldn't an empty drysuit yield the same result?

A total failure of a drysuit, i.e. torn suit, open zipper etc. can in theory loose all of it's buoyancy, but you are missing the point.

The drysuit is the redundant buoyancy.

The drysuit also provides far superior thermal protection. Two birds, one piece of gear, none of the downsides of a redundant bladder wing.

With very few exceptions the depths and exposure times that demand the use of doubles also require better thermal protection than a wetsuit can provide.

IMO Redundant bladder wings are a tax on the ignorant, they mainly serve to make drysuits more expensive.

Who buys these redundant bladder wings? Divers who want to too quickly move to doubles, but either aren't ready or can't afford it. Most of these folks have no real idea about what's necessary for thermal protection for a 120 minute dive.

Joe Wetsuit buys a $500-$700 redundant bladder wing so he can strap on a pair of tanks and go diving.

If he actually sticks with doubles on a regular basis pretty soon he realizes that wetsuits really aren't the "hot ticket" for doubles, they compress at depth and shaking like a leaf without the option to surface now is no fun.

Joe wetsuit needs a drysuit, but the "scuba fund" is $500-$700 lighter thanks to the delux, dubble throwdown full bungee, 100 lbs redundant mega wing in the dive box, oh well maybe next year.

Maybe he can ebay it for 1/2 what he paid to the next Joe Wetsuit.

Tobin