Double bladder question

[Big Toes]

hey all:

i'm new to this group, but have posted some stuff in other forums. i recently got 'peer pressured' into taking a fundies class here recently and had a really good time. cool stuff!

so during the course of the class i had some questions (i've got that engineering type of brain so probably overthought some stuff) but one thing that i've heard that isn't DIR is the double bladders. did i misunderstand that or is it correct?

now please understand that the gear i used for the course was borrowed (twin steel 100's w/twin SP MK25/SP600's with a 5' hose (not my rig; i know it should be 7') on a deep outdoors SS backplate w/twin bladder 85# lift and a 12# triangle weight.

other than a couple of fit issues on day one, things went swimmingly. yet i still have the question: what's wrong with the double bladder? if i'd have to run a secondary LP hose to the power inflator on that one i'd understand. but what about it just sitting passively in it's pocket, ready for oral inflation if needed? seems like a good setup to me, but just wanted to ask.

thanks in advance for any help.

erik

 

[PerroneFord]

I'm surprised you were allowed to proceed in Fundies with an 85# lift wing. Much less a double bladder wing.

That said, I am curious to know your Fundies instructor's thoughts on your question.

For me it boils down to what problem does the double bladder solve? In what scenario would you find yourself that a catastrophic loss of the wing would put you in peril. The trick is to not put yourself in that position in the first place rather than buying gear to rescue yourself should a problem occur.

The double bladder wing is often given as a solution for those who want to dive heavy steel tanks in a wetsuit. The thinking being that should a failure occur, you can simply go to the backup. To me, the problem is that you aren't diving a balanced rig in the first place, thus necessitating a gear solution. If you are doing a dive that is significant enough to require large steel tanks, then why are you diving wet? If the dive is deep, you're going to be in deco. If the dive is shallow but long, then thermal protection is going to be warranted. So the correct answer is to wear a drysuit. And along with that comes redundant buoyancy.

When we examine the failure modes of the double bladder wing, it seems a lot less useful than we might like to admit. After fooling with one for the first day of cave class, I ditched it, and went to two wings instead. I didn't use a drysuit then as I didn't own one. But I started my funding for one very shortly thereafter.

So in short, the double bladder is not DIR because it offers a less than optimal solution to a problem that should never exist in the first place.

 

[Big Toes]

i don't dive wet; i dive dry almost 100% of the time. i understand the redundancy of the drysuit, but the question remains; why not have that extra bladder in there?

if i was diving wet, wouldn't it be a great backup? (i'm not saying that this is a good idea, and i'm not going to do this, just saying...). so is there a specific reason for not having a second bladder? still waiting to hear...

on another note (and again me being very new to doubles and wings) that wing seemed VERY large for those bottles! after my first dive with my instructor i did the usual 1/2 mile hike out to scripps canyon (sucked) and then the subsequent :20 swim out to the site. the entire time i felt like i was rolling around on a waterbed, feet were out of the water, etc. is this wing possibly too big for these doubles?

erik

 

[Big Toes]

so sorry, one last note:

PerronFord, you mentioned the drysuit as backup inflation. i don't know if you've ever tried it but it's skechty at best. why not use another bladder? just looking for info here...

erik

 

[nadwidny]

PerronFord, you mentioned the drysuit as backup inflation. i don't know if you've ever tried it but it's skechty at best.

I have tried using a drysuit as backup. When I first started diving dry it was my only means of buoyancy compensation as I learned to dive dry without a BC. It's not as sketchy as one would make it. It's actually pretty easy and at the time I argued that it was a superior method to using a BC and a drysuit since one only had to handle one expanding lift source in case of an uncontrolled ascent. After that I went with double bladders but

why not use another bladder? just looking for info here...

Try the search function for this forum. Your question comes up quite often and has been rehashed over and over. What did your DIRF instructor say?

 

[Big Toes]

he likes the double bladder. what he doesn't like is having it attached to some form of power inflator, which i totally agree with. why not have that little guy just snugged into a little pocket in the event that you need him? i agree with the fact that you can use a drysuit as a backup inflation device, but it also really sucks in relation to a real wing (I think that anybody that's had to do blue water deco using a drysuit only can attest to this). so why not have a backup wing? i'm dying here!

erik

 

[nadwidny]

he likes the double bladder.

Then you didn't do a DIR fundies.

what he doesn't like is having it attached to some form of power inflator, which i totally agree with. why not have that little guy just snugged into a little pocket in the event that you need him? i agree with the fact that you can use a drysuit as a backup inflation device, but it also really sucks in relation to a real wing (I think that anybody that's had to do blue water deco using a drysuit only can attest to this).

Well I have and it doesn't.

so why not have a backup wing? i'm dying here!

erik

Once again, search is your friend.

 

[Big Toes]

you still haven't answered my question here (by the way love your pic!). Why on earth would you not have that secondary bladder? Not trying to start an argument here, but just really want to know why.

erik

 

[Bismark]

you still haven't answered my question here (by the way love your pic!). Why on earth would you not have that secondary bladder? Not trying to start an argument here, but just really want to know why.

erik

Because you don't need it.

 

[Big Toes]

well i might not need it, but why not take it? there's no redundancy issues, so what's the problem?

erik