Which rebreather and why?

A Place for Discussions On All The Various mCCRs, eCCRs, SCRs & Diving Profiles.

Postby chickdiver » Fri Mar 02, 2007 3:24 pm

Andy wrote:
chickdiver wrote:The idea that a constant setpoint buys you a whole bunch of time off deco is really a myth unless you are talking about extremely long dives. Running the profile with a constant PPO2 vs. OC buys you typically >5 minutes.


Sorry, you're going to have to run this one past me again....

What I think you're saying is that if you dived a perfectly square profile, where on OC you've got the same bottom ppO2 as on the breather - then you you've essentially got the same actual deco time on the two, give or take a few minutes.

The difference, I guess, comes in that if you're multilevelling the dive (like I can afford a VR3 right now...!), that the fO2 is increased to keep the ppO2 on the breather constant as you come shallower then it's making a huge difference on your NDL as the ppO2 is always 1.2-1.4, whereas on OC it's dropping as you ascend.



Well, that's enough for me... thanks for that. Scratch that one off the list.


THat's the basic idea. When we dive OC, we rarely dive a true square profile. It's always somewhat multi-level, and most often we spend times at varying depths- right? So... PO2 changes constantly during the dive. If you are aiming for a bottom PO2 of say... 1.2, and end up spending a significant portion of the dive 30 feet shallower, you have a PO2 of less than 1.2. With a rebreather, if I decide on a setpoint of 1.2, then my PO2 remains 1.2 regardless of depth fluctuation.

Theoretically this should buy me some credit in the decompression obligation. One of the arguements in favor of rebreathers has alwasy been the decompression advantage gained by constant PO2. In reality the benefit gained with regard to decompression is very slight, unless you start talking about VERY long dives. In fact, the time savings usually isn't worth running new tables for.

Does that help?
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Postby Andy » Fri Mar 02, 2007 5:45 pm

thanks, heather. always want to know more! what it will probably boil down to in the end is the access to training. i know (and trust) an inspiration trainer in NZ but think that the nearest Meg trainer is in Aus.

Might even consider going to the UK to buy a breather, do the training there, and bring it back home claiming back the VAT. Will have to wait and see.
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Postby silent solutions » Fri Mar 02, 2007 8:24 pm

Plan and simple there is no perfect rebreather to date they all have there pros and cons.I was after something to replace my inspiration not that long ago and the meg was on the list but no support in this country and no on board deco plus the large wait time.next was the mk 15.5 bit large to travel with but bullet proff all the same.so the inspo had a overhaul and only the lungs and scrubber are the standard items left on the unit.And a tip for those that are considering the current units when some one says wait for this unit or that like the cis belive it when you can touch or see one in person there are alot of false promises in this market.If I was in the market for a unit(eccr) in nz now it would be a inspiration purely for the support they have in this country.If it was a manual unit wait(yeah I know I have just contradicted my self) till afetr oztek for the eagle from colkan.For some reason there will always be a pissing contest between different owners of brands. Rebreathers are a tool to get a job done just choose the best one for your needs.This is just my 2 cents
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Postby Flipper » Fri Mar 02, 2007 9:00 pm

Thanks for your thoughts (and honesty) SS; I'm still a way off buying a CCR, but it *will* happen at some point.... :o)
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Postby Andy » Fri Mar 02, 2007 9:37 pm

Same boat as me, Flipper.... hopefully this year, but who knows.

silentsolutions - thanks for the input, all very valuable. The inspo is top of the list simply because of the accessibility.... but then again, got some overseas trips planned this year so who knows>>??
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Postby chickdiver » Sat Mar 03, 2007 1:06 am

silent solutions wrote:Plan and simple there is no perfect rebreather to date they all have there pros and cons.I was after something to replace my inspiration not that long ago and the meg was on the list but no support in this country and no on board deco plus the large wait time.next was the mk 15.5 bit large to travel with but bullet proff all the same.so the inspo had a overhaul and only the lungs and scrubber are the standard items left on the unit.And a tip for those that are considering the current units when some one says wait for this unit or that like the cis belive it when you can touch or see one in person there are alot of false promises in this market.If I was in the market for a unit(eccr) in nz now it would be a inspiration purely for the support they have in this country.If it was a manual unit wait(yeah I know I have just contradicted my self) till afetr oztek for the eagle from colkan.For some reason there will always be a pissing contest between different owners of brands. Rebreathers are a tool to get a job done just choose the best one for your needs.This is just my 2 cents


You are absolutely correct, access to service and support is a HUGE factor in choosing a rebreather! I also totally agree on the comments on "vaporware"- items are routinely announced as "about to be released" only to never materialize.
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Postby Flipper » Sat Mar 03, 2007 7:36 am

chickdiver wrote:You are absolutely correct, access to service and support is a HUGE factor in choosing a rebreather! I also totally agree on the comments on "vaporware"- items are routinely announced as "about to be released" only to never materialize.


Exciting times - reminds me a bit like the early days of IT. The level of vapourware may be annoying, but it does at least mean that there's a bunch of people out there pushing the boundaries (and then marketing get hold of the ideas and try to float them before they're water-tight,,, gotta love marketing :roll: ) With the innovation going on in the background, and what seems like an ever increasing demand for good, usable and realiable breathers (as opposed to rebreathers for the sake of rebreathers) then I'm certain that good things are in the pipeline. I'd better start saving :)
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CCr

Postby Simon TW » Mon Mar 05, 2007 9:20 am

The CIS Lunar was sought after because of the scrubber, Innerspace has the rights to manufactre the CIS scrubber for use on the Meg. I don't have any idea of prices but the factory are more than helpfull. The recent Megs are made so that they will interchange so if you won a meg you can but different cans and heads and just swap around.

Eveyone told me how good the Meg is for travel but it isn't. It's way to heavy for airline baggage. An Inspiration with cylinders is 32k the maximun allowed on a UK airline the MEg is that without Cylinders. The new transatlantic baggage restrictions ar enow 23k max per bag. You would have to saw your Meg up to get it on a flight. Yes it packes small but it weighs a ton.


I own a Meg a few Inspirations and an Evolution and first choice is an Inspiration. That may change when the Apeks 3 Deco software comes out and the new Carbon Fibre cannister but until then..
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Re: CCr

Postby chickdiver » Mon Mar 05, 2007 10:00 am

Simon TW wrote:The CIS Lunar was sought after because of the scrubber, Innerspace has the rights to manufactre the CIS scrubber for use on the Meg. I don't have any idea of prices but the factory are more than helpfull. The recent Megs are made so that they will interchange so if you won a meg you can but different cans and heads and just swap around.

Eveyone told me how good the Meg is for travel but it isn't. It's way to heavy for airline baggage. An Inspiration with cylinders is 32k the maximun allowed on a UK airline the MEg is that without Cylinders. The new transatlantic baggage restrictions ar enow 23k max per bag. You would have to saw your Meg up to get it on a flight. Yes it packes small but it weighs a ton.


I own a Meg a few Inspirations and an Evolution and first choice is an Inspiration. That may change when the Apeks 3 Deco software comes out and the new Carbon Fibre cannister but until then..


I carry my Meg on board in a standard sized rollaboard. No one has ever asked to weigh it. There's no f*****g way I am putting it in checked baggage. I've been traveling with dive gear for aobut 15 years now, and I never check the important stuff.
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Re: CCr

Postby Simon TW » Tue Mar 06, 2007 7:43 pm

[quote="chickdiver]
I carry my Meg on board in a standard sized rollaboard. No one has ever asked to weigh it. There's no f*****g way I am putting it in checked baggage. I've been traveling with dive gear for aobut 15 years now, and I never check the important stuff.[/quote]

Yeah but I travel worldwide, internal flights and to and from the USA is fine but if youtravel anywhere in Europe, Aisa, Africa or anywhere else other than North America your stuffed.

Believe me they need to do a lighter travel unit, Leon has a Carbon Fibre Can but they haven't put it through testing. If it works then the Meg would be usefull for travel.

Right now the Inspiration is the only unit you can travel the world with.
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Re: CCr

Postby chickdiver » Wed Mar 07, 2007 1:19 am

nevermind......
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Re: CCr

Postby Azza » Wed Mar 07, 2007 6:31 am

Simon TW wrote:Yeah but I travel worldwide, internal flights and to and from the USA is fine but if youtravel anywhere in Europe, Aisa, Africa or anywhere else other than North America your stuffed.
<snip>
Right now the Inspiration is the only unit you can travel the world with.

Simon as far as I know Chickdiver and the rest of her team do dive internationally...I would imagine they are taking their Megs with them when they visit Truk very shortly
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Re: CCr

Postby Simon TW » Wed Mar 07, 2007 9:31 pm

Azza wrote:
Simon TW wrote:Yeah but I travel worldwide, internal flights and to and from the USA is fine but if youtravel anywhere in Europe, Aisa, Africa or anywhere else other than North America your stuffed.<snip>
Right now the Inspiration is the only unit you can travel the world with.

Simon as far as I know Chickdiver and the rest of her team do dive internationally...I would imagine they are taking their Megs with them when they visit Truk very shortly


Azza, as I stated earlier the baggage allowance is much less outside the USA, this is a NZ forum and unless you travel Business Class or have a special deal you are restricted flying out of NZ.
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Re: CCr

Postby Azza » Thu Mar 08, 2007 9:25 am

Simon TW wrote:the baggage allowance is much less outside the USA, this is a NZ forum and unless you travel Business Class or have a special deal you are restricted flying out of NZ.
I dont know how much a Meg weighs but I have been given 48 kg in budget class out of NZ numerous times...You just have to mention you are a diver and its usually free...
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Postby Andy » Thu Mar 08, 2007 9:37 am

Most airlines have a sporting baggage allowance, buried deep in the small print, and normally if you phone in advance they can give you the ok without an excess baggage charge.

I've taken my sea kayak as luggage before, so I'm sure a breather shouldn't be too difficult!

The other option, and I know some of the local breather divers do this (particularly after one of them took his sorb out of the bucket and packed it in zip lock bags and tried to take it on as hand luggage! Doh!) is ship the breather and as much sorb as needed by courier before hand.
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