multi-level diving not suited to CCR use...!?

[Justin Owen]

reading an evo review earlier, the comment was made that CCR isn't that suited to multi-level diving? am i being a complete fcuk-wit or isn't this one area a CCR would be extremely benficial? i.e. the best nitrox mix at every depth without additional stages etc?

spending all day saturday on an Evo in north wales - might be joining the no bubbles crowd sooner rather than later...!?

(if i can use it for multi-level diving that is!)

[jptaylor9]

I e-mail the author of the article saying I wasn't sure he was correct on that point, no reply yet. Don't think he actually dives the unit much, just did a course.

I think he was getting confused between "saw tooth" profile dives. Bad regardless of if your on OC or CCR. But on CCR you use a lot of gas as you dump & refill the loop.

I recently did a long dive on the Zenobia, did 25mins @ 42m, 25 @ 35m, 25mins @ 25 - 30m & finally 25mins at 20min. I'd call this a multi-level dive!

Unit worked well, racked up 30mins of deco on initial deep leg, but it didn't increase as I came shallower (as you sort of expect)

JT

[Deep Baloo]

Where did you dive out of for the Zenobia,I was talking to John Thornton the other day and he expressed an intrest in getting a few blokes together and diving it,so any info you have would be good

[jptaylor9]

Originally Posted by mrbwhite

Where did you dive out of for the Zenobia,I was talking to John Thornton the other day and he expressed an intrest in getting a few blokes together and diving it,so any info you have would be good

It was a trip organised by Mark Powell, details on YD.

We used Dive-Tek Cyprus, they have both Inspiration cylinders & lime. They'll have a stand (#1621) at the NEC Dive Show.

JT

[nigelH]

Originally Posted by Justin Owen

the comment was made that CCR isn't that suited to multi-level diving? am i being a complete fcuk-wit or isn't this one area a CCR would be extremely benficial? i.e. the best nitrox mix at every depth without additional stages etc?

I admit it would be my preference.
There is nothing I know that I can't do better on an ECCR. Even nose down in archaeological silt with one handset clipped off under my chin I prefer it. The only time it has to go is if we need comms (see avatar).

[BJ]

The problem can arise from reviewing a bit of kit without actually using it. I think the author got confused with the business of swimming round things rather than over them (eg. you have to adjust buoyancy on the BC to do it wheras on OC you simply adjust your breathing.)

Needless to say the Evolution or Inspiration CCR is perfect for multilevel diving.

[NotDeadYet]

It depends how you're doing your multi-level dive. If it's a traditional swim to the deepest point and gradually work shallower then there is no problem.

However, in cave diving where you have no choice but to follow the profile of the cave, then if it has lots of uppy downy then it will eat through diluent. I've emptied a 3L dil bottle before, admittedly there were other contributing factors.

I guess in the above example, the reviewer doesn't really understand the concepts involved (a bit worrying if he's just done a course). Another good reason not to read reviews.

[Decodiver]

Yeah, as said above, reviews are only as good as the reviewer.

Now I would listen more to a review of a CCR by an experienced CCR diver rather than someone who just goes somewhere nice to dive and dives CCR only when reviewing them.

Tall-skinny-grey-haired-talker-of-bollocks-springs-to-mind.

That is why Bish's review of the Boris was one of the contributing factors in my decision to buy one, not only does he have extensive CCR experience, but his review was informative and constructively critical where necessary.

CCR is ideally suited to multi-level diving, in fact there is nothing better, as pointed out though, sawtooth profiles will eat through your dil and O2 in no time at all.

HTH.

Cheers,

Dave Cooper.

[Mark Chase]

There is a school of thought that CCR is not suitable or easiest used for dives where numerous depth changes are forced upon the diver. An example of this would be a cave dive where the depth was constantly changing and the diver is forced to follow the cave. The problems of buoyancy control and managing the volume of the counter lungs are an irritation and the gas usage is high so gas logistics of the CCR become distorted.

Add to this the small cylinder size on the Evo. When i first used the classic with its 3ltr cylinders i used a lot of diluent on wing inflation and suit inflation. As a result a two dive day would push the little 3ltr tanks if i started with a light fill. This early lack of buoyancy control is similar to being forced to run a jagged profile. As a result the little 2ltr tanks on the Evo would be hard pushed to cope.

Obviously the cure for this is off board suit and wing inflation but the article obviously was not well informed. What most people consider to be "multi level diving" is perfectly suited to the Evo or any other CCR I can think of.

Hope this helps.

ATB

Mark Chase

[Phoenix]

Originally Posted by Mark Chase

There is a school of thought that CCR is not suitable or easiest used for dives where numerous depth changes are forced upon the diver. An example of this would be a cave dive where the depth was constantly changing and the diver is forced to follow the cave. The problems of buoyancy control and managing the volume of the counter lungs are an irritation and the gas usage is high so gas logistics of the CCR become distorted.

Add to this the small cylinder size on the Evo. When i first used the classic with its 3ltr cylinders i used a lot of diluent on wing inflation and suit inflation. As a result a two dive day would push the little 3ltr tanks if i started with a light fill. This early lack of buoyancy control is similar to being forced to run a jagged profile. As a result the little 2ltr tanks on the Evo would be hard pushed to cope.

Obviously the cure for this is off board suit and wing inflation but the article obviously was not well informed. What most people consider to be "multi level diving" is perfectly suited to the Evo or any other CCR I can think of.

Hope this helps.

ATB

Mark Chase

No such problem on boris however, wing & suit have to be fed externally leaving the 2ltr onboard cyls for breathing only.

Ian