Need Help - Dual Bladder BC, which ones and where to buy

[japan-diver]

A double bladder wing adds additional failure points and complication to your rig while adding very little in the way of backup. A malfunctioning inflator can easily be disconnected and a wing orally inflated. If you were to tear a wing it would must likely tear both bladders as they are stacked on top of each other.

A balanced rig with back up buoyancy is a much better solution than a dual bladder. In a overhead environment back-up buoyancy is a must but having all your buoyancy on your back in a wing is not a good solution.

Just my opinion after 15 years of tech diving and teaching tech- overheads and caves and deco.

 

[frogdrvr]

A double bladder can be useful when you are diving wet, with steels and stages. You are not going to be able to swim it and by the time you get your lift bag inflated you could be standing on the bottom.

I am interested, who has seen a dual bladder failure? I hear people say all the time, what punctures one will puncture the other, but have yet to have met anyone who has seen a dual bladder failure.

 

[Zeke XA3]

Thanks for the input guys i will talk to my tech and cave instructor in more detail about why they want a dual bladder and check costs as well.

Cheers
Z

 

[danvolker]

A double bladder can be useful when you are diving wet, with steels and stages. You are not going to be able to swim it and by the time you get your lift bag inflated you could be standing on the bottom.

I am interested, who has seen a dual bladder failure? I hear people say all the time, what punctures one will puncture the other, but have yet to have met anyone who has seen a dual bladder failure.

Deep diving with double steels and heavy wetsuits is a violation of common sense. There is no intelligent instructor or agency position on this being a proper method to perform deep diving with. The idea that a dual bladder wing could mitigate the problems of decreased suit bouyancy with depth, is the kind of idea that kills tech divers. If an instructor or agency suggests this as a good solution for dives at technical diving depths, this should be seen as a massive warning that they are the WRONG source of advice or training for you. Period.

If you want steels on a tech dive, you will want to be in a drysuit. If you wear a thick wetsuit on a tech dive, by the time you are at 220 feet down, the warmth it offers is little more than that of a lycra skin, and the huge swing in bouyancy would then have you swimming with enormous amounts of air in your wings---meaning you are pushing much harder to get through the water at any speed, and sucking much more air, AND, you are very cold, with your muscles losing efficiency as you become more hypothermic.

You want very little air in your wings----the big air double bladder concept turns a diver into a puffer fish that can't move without expending huge energy. You need to be slick in the water, and you need to be warm.

 

[Belmont]

One friend had to replace his huge double bladder OMS wing last week. He was cave diving in Mexico and using twin aluminum 80's.

The bulk of the wing with it's added material made it very difficult to fit on the tanks, the bolts being too short.

He lost a lot of dive time fiddling with his rig. His instructor finally put his foot down. He went to a local LDS and bought a proper Halcyon wing.

 

[frogdrvr]

Dan. The question is not the added bouyancy that comes from having a dual bladder wing it is the redundancy. You dont use both bladders at the same time. What might not make sense for you at 220ft makes alot of sense at 165ft. Its much simpler to dive wet in warm water environments at that depth.

As to your comment not worthy instructor would advocate the position that diving wet with dual bladders wings, the DSAT/PADI Deep Tech mandates the use of a dual bladder wing for redundancy.

 

[Zeke XA3]

Danvolker - Thanks for that, a lot of info there i hadent thought about. Is it common then to still use Drysuit in the tropics for deep diving? How do you negate the heat risks while gearing up in 40C heat? Would a solution be using things like Shark Skins due to their neutral buoyancy and therefore not changing at depth? And is this only for Steels are the problems described a lot less with Alys?

Belmont - Im confused , where the tanks extra big? Surely he would have checked when he bought the rig that a set of tanks would fit on with the current bolts? I remember helping a mate set up his bands when he first bought them and we sat in his living room making sure everything fitted before even getting the tanks filled!

Frogdvr - Interesting point for the PADI courses there !

From the TDI i have been told - "buoyancy compensator(s) suitable for the equipment configuration"

If im diving wetsuit in the tropics that would mandate....dual bladder?

 

[iztok]

If im diving wetsuit in the tropics that would mandate....dual bladder?

Drysuit for steel or use AL with wetsuit.

It shouldn't be too bad putting proper drysuit on even in the tropics. Trilam with light undergarments should work just fine.

 

[danvolker]

Dan. The question is not the added bouyancy that comes from having a dual bladder wing it is the redundancy. You dont use both bladders at the same time. What might not make sense for you at 220ft makes alot of sense at 165ft. Its much simpler to dive wet in warm water environments at that depth.

As to your comment not worthy instructor would advocate the position that diving wet with dual bladders wings, the DSAT/PADI Deep Tech mandates the use of a dual bladder wing for redundancy.

I am well aware of what the dual bladder is supposed to do.... the point is the way bouyancy is dealt with is all wrong. A smart diver will not dive to technical depths with double steels and a thick wet suit.

 

[danvolker]

Danvolker - Thanks for that, a lot of info there i hadent thought about. Is it common then to still use Drysuit in the tropics for deep diving? How do you negate the heat risks while gearing up in 40C heat? Would a solution be using things like Shark Skins due to their neutral buoyancy and therefore not changing at depth? And is this only for Steels are the problems described a lot less with Alys?

Belmont - Im confused , where the tanks extra big? Surely he would have checked when he bought the rig that a set of tanks would fit on with the current bolts? I remember helping a mate set up his bands when he first bought them and we sat in his living room making sure everything fitted before even getting the tanks filled!

Frogdvr - Interesting point for the PADI courses there !

From the TDI i have been told - "buoyancy compensator(s) suitable for the equipment configuration"

If im diving wetsuit in the tropics that would mandate....dual bladder?

I dive in south Florida, and in summer, we have plenty of dive days with near 100 degree heat. You put the suit on, and can get sprayed down repeately to stay cool before jumping in the water. By 150 feet, we are usually hitting much cooler water than the near 80 degree surface water of July....often it will be in the mid 60's deeper than 150, and many times by 280 it can be much colder than this. The wet suit was tried and tried again--by us in the early days--it was a piss poor solution at depth, and whenever the thermoclines were significant.

The suit is not for the boat ride. The dual bladder wing might sound good in the showroom, or be fine sitting on a tank on the boat. when you actually dive deep, it pays to use the right gear. the gear that is optimal for time at max depth, and throughout most of the deco.
If you are diving some place so tropical that the water is warm/hot all the way down, then by all means, wear a skin suit---and then have no suit induced bouyancy shift. And with the much reduced drag, you should need no more than dual 80 aluminums. Trouble is, I don't have any places I know of like that, I can reliably expect to be hot water all the way to the bottom.