DIR- Generic dual bladder wings...

[crofrog]

Me and John Chatterton rocking LP85's in wetsuits, me with my bungied double bladder wing. The horror!, the horror!View attachment 719418

Appeal to authority is a logical fallacy; it is entirely possible that the opinion of a person or institution of authority is wrong; therefore the authority that such a person or institution holds does not have any intrinsic bearing upon whether their claims are true or not.

If your dive numbers are accurate, you're demonstrating that you drank the koolaid but don't know what's in it. The greatest names in diving are all wrong and you're right. Got it. Good luck in your diving career with an attitude like that. Signing off.

What's interesting is that actually only one of us is acting in a close minded way, and guess what it's not the guy with only a few hundred dives.

 

[ginti]

Me and John Chatterton rocking LP85's in wetsuits, me with my bungied double bladder wing. The horror!, the horror!View attachment 719418

Dude, we all know that you will not die just because of a double bladder wing. And if you want to use it, we really don't care: no, it isn't horror at all!

This post isn't about the best configuration, it's about why double bladder aren't a thing within the DIR community. Anything in life has advantages and disadvantages, and within the DIR community people believe that double bladder disadvantages are more important than the advantages. What's wrong with that? If you don't like it, nobody will tell you that you should adhere to this philosophy. If you believe that, in certain situations, double bladder wings are more advantageous than single bladder ones, by all means go for this solution. Just dive as you want and let others dive as they want

 

[Lorenzoid]

Just dive as you want and let others dive as they want

Ironically, people will come into the DIR forum and tell us just that. As though people in here are telling others how to dive.

 

[ginti]

GPT-3 is getting more and more realistic every day, but there are still some unusual quirks.

Playing with it right now... it still has to learn a lot about the diving world:

I admit that the first one was quite good

 

[kensuf]

Playing with it right now... it still has to learn a lot about the diving world:
View attachment 719466

I admit that the first one was quite good

Just pay attention to all of the Alaskan Scuba Dude's posts. I'm all but convinced it's GPT-3.

 

[bakodiver391]

Dude, we all know that you will not die just because of a double bladder wing. And if you want to use it, we really don't care: no, it isn't horror at all!

This post isn't about the best configuration, it's about why double bladder aren't a thing within the DIR community. Anything in life has advantages and disadvantages, and within the DIR community people believe that double bladder disadvantages are more important than the advantages. What's wrong with that? If you don't like it, nobody will tell you that you should adhere to this philosophy. If you believe that, in certain situations, double bladder wings are more advantageous than single bladder ones, by all means go for this solution. Just dive as you want and let others dive as they want

I get it, but when someone tells me what i do and don't understand, from a position of no knowledge whatsoever, as evidenced by nitpicking about tank brand names, I have to defend my professional reputation. Instructors in the group would be doing the world a favour by teaching their acolytes to be less...strident. You seem to have a balanced view, the other guy not so much. I tried to sign off once, will do so now.

 

[crofrog]

I get it, but when someone tells me what i do and don't understand, from a position of no knowledge whatsoever, as evidenced by nitpicking about tank brand names, I have to defend my professional reputation. Instructors in the group would be doing the world a favour by teaching their acolytes to be less...strident. You seem to have a balanced view, the other guy not so much. I tried to sign off once, will do so now.

I said you demonstrated you didn't understand it, you continue to do so. There is a difference.

 

[boriss]

I said you demonstrated you didn't understand it, you continue to do so. There is a difference.

Are you sure that's what you did? I'm reading the opposite. Let's see...

Aluminium tanks have terrible buoyancy characteristics. The swing from negative to positive, and most of the buoyancy in the bottom third of the tank, make them unusable to me. Also they don't have enough capacity for long penetration dives. So I'm happy with my lp85's and double bladder setup.

You realize the weight swing from neg to positive doesn’t actually matter right and in someways can be helpful. As it reduces the tanks weight as a percentage of your total weighting and can allow you to then place that weight where you want it.

The total weight swing is a function of the vol of gas carried not the cylinder.

^ This response didn't address the buoyancy characteristics, just the weight swing

I have several thousand technical dives under my belt. i feel that I've given aluminium tanks a fair trial and then kicked them to the curb. They may work for you, they don't work for me. End of story.

Sure, but for 1000s of technical dives I'm surprised you to understand that swinging from neg too positive on a tank doesn't actually matter, for that matter some steel LP85's and HP133's do the same thing and there are some AL80s that end neutral to negative...

^ Isn't this a misunderstanding on your part, not his? You're talking about the weight of gas and the swing from being negative to positive buoyancy, while he's talking about trim.

As I alluded to in saying that the buoyancy is in the bottom third of the tank, it is the change in longitudinal TRIM that I can't stand in ali tanks. There is a lot of metal in the dome and neck of an ali 80, much more so than a steel tank where the wall thickness is the same all over, and the neck is thin. An empty ali tank is buoyant in the base, an empty LP85 does not change trim. This change in TRIM could be deadly in a challenging penetration. My mentors had 15,000 dives, and I've never seen them dive with ali tanks.
My first several sets of doubles were ali, and I tried to like them. i even cast an hourglass shaped weight to fit between the tanks at the base, which fixed the trim problem, but begs the question" why bother to weigh these tanks down with a non-ditchable weight so that they perform like steel tanks, when the solution is to dive steel tanks?"

Are you talking about luxfer 80 or s80 or metal impact or Catalina s80 or C80? For the steel tanks are you talking about oms 85s, one of the 13 flavors of Faber 85s, or one of the Pst variants.

All of those above tanks have different trim and bouyancy characteristics. You dive the gear the gear doesn’t dive you.

As for the numbers of dives you or your mentors is an irrelevant appeal to authority, you’re demonstrating that you don’t fully understand the variables in the system.

The tanks he used were clearly demonstrating this (even though we've established it can be controlled in many ways), but more importantly he said they did't carry enough gas and they don't work for him.

Only pointing out that benign opinions expressed on ScubaBoard tend to balloon into the biggest of issues (due to a clear misunderstanding by the guy blaming the other one for misunderstanding!!) and talked about for pages on end. This is literally the only forum I belong to where I'm afraid to post and I have to read everything I write from a dozen different angles to ensure I don't get blasted by the ScubaBoard Police. It's a shame, IMO. I can understand intolerance when something is a legitimate safety concern, but this? C'mon! There's no way people would talk to each other this way in person.

I digress. I'm sorry, had to vent. Going back into my cubby-hole. Carry on boys!

 

[Wibble]

...So now you are looking at steel 85s, 100s and for those who do deep tech 1 dives or tech 2 dives, you are talking about steel 120s at least.

Errm, cough... you mean a rebreather.

OC is so old school and now just about impossible to get enough helium for any deeper dives -- gas costs alone are now many hundreds of $$$ per dive -- unless you've a secret stash. Have heard it's $5/cubic foot (17¢/litre for people outside the parochial USofA), meaning your twin 120's at 50% helium would be $600 to fill just with helium!

For those not familiar with a rebreather, it would be $30 for the same dive (100 litres at 17¢ = $17 plus $3 for oxygen and $10 for the sodalime/sorb/scrubber) -- and that price is for pretty much any depth below 50m/165ft. Yeah, yeah, add in the ~$20k for the unit and training...

 

[crofrog]

Errm, cough... you mean a rebreather.

OC is so old school and now just about impossible to get enough helium for any deeper dives -- gas costs alone are now many hundreds of $$$ per dive -- unless you've a secret stash. Have heard it's $5/cubic foot (17¢/litre for people outside the parochial USofA), meaning your twin 120's at 50% helium would be $600 to fill just with helium!

For those not familiar with a rebreather, it would be $30 for the same dive (100 litres at 17¢ = $17 plus $3 for oxygen and $10 for the sodalime/sorb/scrubber) -- and that price is for pretty much any depth below 50m/165ft. Yeah, yeah, add in the ~$20k for the unit and training...

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