Independent Doubles vs. Isolated Doubles

[captain]

Oh dear, more attempted point scoring. Why would you assume that I don't know how to inflate a bladder orally, just because I prefer to do it with tank air?

And why do you say that two wings (not that that is what I said - I said one wing with two inflatable bladders) are unnecessary especially in warm water? In those circumstances you typically have no other usable redundant buoyancy - what do you do if your sole bladder ruptures or otherwise won't hold air? I know of deaths specifically because the people concerned did not have redundant buoyancy readily available to them. I had to recover the body of one of them, from 125mtr.

I assume by warm water you mean no wet suit required. If that is the case I would not dive so negative that I could not swim my rig up.

 

[peterbj7]

There are times when that's difficult to achieve. An example I have in mind is a (very) deep dive made in order to film/photograph.

In any case, I don't mean no wetsuit required. I mean not much insulation required. If you make a long dive you still need insulation, regardless of how warm the water is (assuming it's not blood temperature). Something like a 5/3mm suit - that certainly gives rise to buoyancy considerations, regardless of what other gear may be carried.

 

[Packhorse]

A HP HOSE failure will only result in a slow leak as the gas will be coming out of a pinhole restriction in the reg. Would take around 20 minutes to empty an 80 from full.

A neck O ring or burst disc failure can empty a tank in 90 seconds or so,roughly the same as a LP hose failure.

This all depends on the size of the hole in the 1st stage HP port. Some I have seen are relatively large.

 

[Nemrod]

Oh dear, more attempted point scoring. Why would you assume that I don't know how to inflate a bladder orally, just because I prefer to do it with tank air?

And why do you say that two wings (not that that is what I said - I said one wing with two inflatable bladders) are unnecessary especially in warm water? In those circumstances you typically have no other usable redundant buoyancy - what do you do if your sole bladder ruptures or otherwise won't hold air? I know of deaths specifically because the people concerned did not have redundant buoyancy readily available to them. I had to recover the body of one of them, from 125mtr.

Dude, you can do it however you like, you can have 50 failure points and enough hosing to tube an aircraft carrier, no points needing scored. Your two statements are opposites. I prefer to eliminate duplication and extra hoses and failure points.

Get yourself a custom Rubatex G231 N suit, they don't flatten out like all most ALL of the imported neoprene suits do and thus they don't loose all of their bouyancy.

In the conditions you describe, I would probably just use my sauasge and dispense with all the complication.

Deep huh, how deep are you going?

N

 

[peterbj7]

I'm thinking mainly of dives in the 150'-300' region, and some specific dives in particular. I can assure you that a US-style safety sausage or even a UK-style DSMB would NOT provide enough buoyancy, nor of course would that be controllable.

I'm referring to the addition of one hose, performing a similar job to one already present on the gear. Not "enough hosing to tube an aircraft carrier". In any case, when was the last time you had a BC inflator hose fail? Or perhaps you don't use them at all, avoiding them as unnecessary complications that create failure points?

All neoprene suits will compress at depth, to varying degrees. If they don't they're not providing much insulation.

I also avoid unnecessary complication, but I like to carry gear that will do the job.

 

[captain]

Actually you lose insulation when the neoprene compresses. The less it compresses the more insulation valve

 

[peterbj7]

Actually you lose insulation when the neoprene compresses. The less it compresses the more insulation valve

Yes..... Did I say anything other?

 

[peterbj7]

This all depends on the size of the hole in the 1st stage HP port. Some I have seen are relatively large.

Maybe that will have some effect, but I think you'll find that will be eclipsed by the small hole that runs down the length of the hose. Unless you've seen HP hoses that I've never seen.

I have experienced both HP and LP hose failure, sometimes accidental, sometimes deliberate in training, and I have never seen more than a minute amount of air coming out of an HP hose. A ruptured LP hose will, as someone else said, drain your tank in a very short time if you let it.

 

[Bismark]

There are times when that's difficult to achieve. An example I have in mind is a (very) deep dive made in order to film/photograph.

In any case, I don't mean no wetsuit required. I mean not much insulation required. If you make a long dive you still need insulation, regardless of how warm the water is (assuming it's not blood temperature). Something like a 5/3mm suit - that certainly gives rise to buoyancy considerations, regardless of what other gear may be carried.

I am curious to hear your equipment and weighting for a 150'-300' dive in Belize waters. I assume you are using AL 80's but I am curious as to why you are unable to swim up your gear if your wing goes kaput in warm water with a 3-5mm wetsuit and al-80 tanks. I would say a new diver would be over weighted but for someone of your experience, I wouldn't think that would be the case. I am truly interested in your equipment set up.

 

[Packhorse]

Maybe that will have some effect, but I think you'll find that will be eclipsed by the small hole that runs down the length of the hose. Unless you've seen HP hoses that I've never seen.

I have experienced both HP and LP hose failure, sometimes accidental, sometimes deliberate in training, and I have never seen more than a minute amount of air coming out of an HP hose. A ruptured LP hose will, as someone else said, drain your tank in a very short time if you let it.

I cut a HP hose a week or so ago after replacing it due to a leak. I was expecting what you described. A small hole. It was in fact 3-4mm wide. Im fairly confident this would flow more than a minute amount of air.
Perhaps I should have said this all depends on the size of the hole in the 1st stage HP port and the bore of the hose.