Twinnies

[Kern]

Thanks for the responses. I shall fire of a couple of questions.

For me, it's far more difficult to get Halcyon gear/servicing/warranties. Oxycheq is rather convenient, and it's far cheaper. I would consider switching to a stainless backplate for better trim with difference in pricing...?

So you think a 40lbs wing wouldn't be adequate? I have heard reports of people regretting the added bulk and nonstrealiminess of larger wings.

I have heard reports of these Al80's. I believe the metric equivalent is approximately an 11L tank, which sounds adequate for my needs. How are buoyancy characteristics? Together with a thick wetsuit, would I struggle to remain neutral at shallow stops?

Reading a little, I understand the HP 10's have the same working volume as a LP 12, but with slightly worse trim. Considering I'm roughly 6.2, twin LP12's or AL80's sound like better options.

With pockets, I was refering to an integrated system wearing weights on the waistband? Is that not advocated in technical diving circles?

As your in Oz, an aluminium 80 has a working pressure of 207bar & has about 2100lt of gas. They aren't really 80 cft.

Forget the Nth. American idea of HP & LP tanks. What they call HP is about 232bar. What you're calling a HP 10lt is actually a 300bar tank. So a 300bar 10lt tank has about 3000lts of gas & a 232bar 12lt tank has about 2800lts of gas.

I really don't like the buoyancy characteristics or trim of 300bar tanks. I know others who use 10lt x 300bar twin tanks & love them.

Most of the aluminium tanks you see in Oz hire tank fleets aren't 80's but 90's & 95's. The 90 & 95's have a water capacity of about 11lts, but a working pressure of 240bar, so hold about 2700lts of gas.

 

[Ozgarr]

Thanks for clearing some misconceptions. I was under the impression an AL80 had a far higher working pressure. And, a HP100 is approximately a 12L x 232 bar?

So, in Australia what common setups are used for doubles? I would imagine the aforementioned twin HP100. Are ally 90' and 95's used? From my estimates they would provide very similar working volume ~ 2700L to the 12L.

 

[Kern]

Thanks for clearing some misconceptions. I was under the impression an AL80 had a far higher working pressure. And, a HP100 is approximately a 12L x 232 bar?

So, in Australia what common setups are used for doubles? I would imagine the aforementioned twin HP100. Are ally 90' and 95's used? From my estimates they would provide very similar working volume ~ 2700L to the 12L.

A US, HP 100cft is approximately a 12lt x 232bar. 100cft ~ 2832lts.

Possibly I'v misunderstood what you meant by LP 12's, & HP 10's.

These days steel 12lt x 232bar are the most common tanks I see twinned. You still see some steel 10lt x 232bar tanks twinned, & on the odd occasion you see some smaller steel tanks twinned, & the occasional steel 10lt x 300bar tanks twinned. I'v never seen anything smaller than 10lt x 232bar tanks twinned for tec purposes.

I'v never seen aluminium 90's or 95's twinned, & I'v only ever seen two people use twinned aluminium 80's. The 80's were being used by GUE trained divers, & I would hazard a guess & say that GUE trained divers are the only people you'll see diving twinned 80's in OZ.

PS. If you're serious about tec diving in Melbourne, get a dry suit.

 

[Trace Malinowski]

Halcyon. Steel plate. Aluminum 11 L tanks. 40 lb. wing.

 

[Kern]

Halcyon. Steel plate. Aluminum 11 L tanks. 40 lb. wing.

So Trace, would that be 11.1lt x 207bar, or 11.5lt by 240bar?

 

[Kern]

double post.

 

[Ozgarr]

Possibly I've misunderstood what you meant by LP 12's, & HP 10's.

I was under the assumption a LP 12 had a working pressure of 232 and a HP 10 had a working pressure of 300 bar.

 

[Lobzilla]

What Trace says...steel plate, Halcyon 40lbs Evolve, AL80 tanks. You can't go wrong with that.

Attached is a chart that shows metric and US dimensions. What we call here AL80 is listed as S80.

AL80s are a sweet choice for wetsuits (even a 9/7/6 mm). They trim out on almost every person, whether tall or short. For salt water and/or drysuits most people use a tail and/or V weight between the AL80 tanks.

The negative buoyancy of steel tanks can be problematic with a wetsuit and, depending on your built, you have to pick the right tanks to trim out. Rule of thumb is that if you are tall, the tanks need to be tall as well. Try before you buy.

 

[ucfdiver]

One huge difference is Halcyon will bend over backwards to make you happy as a customer, and Oxycheq will essentially tell you to stop bothering them. Any oxycheq product I buy, I automatically assume there is zero warranty on it, so I have to get a good enough price to justify buying something without a warranty.

 

[Kern]

I was under the assumption a LP 12 had a working pressure of 232 and a HP 10 had a working pressure of 300 bar.

In as much as 300bar is the higher pressure, & 232bar is the lower pressure you're right. We just don't use the convention in Oz. In the US HP is about 232bar & LP is below 207bar, you'd be hard pressed to find a 300bar steel tank.

Everyone keeps telling you about the lousy Oxycheq customer service in the US. As you'll be dealing with an Oz dealer/distributer, I doubt it's worth worrying about. As we're talking about metal plates & one of the most popular wings around, I wouldn't worry about customer service too much.

If you just want to ponce about on rec dives in doubles, get an aluminium 80 & dive a wet suit. If you want to get some worthwhile bottom time on tec dives to 55mts, get a set of 12 x 232's & a dry suit. You're in Melbourne, it'll be cold at depth down there. Don't think redundant buoyancy, think about how a cold body can compromise your deco.

There is no cheap way to play the tec diving game. Get some reasonably sized tanks & a dry suit, & do it proper.