Megalodon or Pelagian

Rebreatherlab

Hi Mike,

The only reason they face up is that this is the only way to fit three cells, ADV, one 9V bat compartment, 2 glands and the in and out holes in a 140 mm diam. head. Ad the fact that for the ICV to work the cell membranes need to be in a position right under the ADV unless complicated SS tubes are used to distribute the DIL flow. I spent a few months playing with it and found that it could be done with K1D's but as I dont like them I settled with what I have. I think it is only a bad compromise if accumulated moisture becomes an issue. After 2 years it is still not an issue. Most CCR courses teach to pull the head off the scrubber to allow moisure to evaporate after diving. I usually dont as the moisture is not an issue. After 2 hrs diving and an O2 loop purge I usually get 1,55 - 1,6 at 6m. At least for a short while until the loop vapour and off gasing inert gas dilutes it.

Would love to do some cave diving. I will have a few weeks off from mid May and spend some time in Krabi and Trang.

Cheers,

Andy

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prinske64

Thanks for al the replys!

henckell

You clearly stated that you had "500 hours on the unit" (Pelagian), which turned out not to be true.
The figure is not as interesting as the fact that you changed it.

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Inspired Trainer

When making comparisons...consider what you want a unit to do. Pelagian is very compact and ideal for travelling, it has very few breakable components, it will work to any depth you are likely to take it. The loop volume and trim is as close to perfect as ive seen. The Megalodon Copis is a similar manual unit, well made leaning towards the heavy side, this is useful to keep the weight belt minimal but not so good to travel with.

If you just want to own a rebreather then any will do and the more money you spend the more perceived credibility it will come with - how many rich people make mistakes - none that they would admit too.

I would ask myself how many users have been killed on a specific design and was it simply crap instruction or can the unit be blamed in any way. I would imagine that WOB in a correctly used unit has contributed to zero deaths. WOB is a useless indicator of whether a unit is good or not rather than bragging currency for those of a particular persuasion.

Joining as many forums as possible will give you access to the various problems associated with each unit. Some of the most expensive units are notorious for flooding or falling apart yet seem to be heralded by their owners (until sold) and also bizarrely sport CE marks which does nothing for the credibilty of the CE system.

Look at the brands of rebreathers coming up for sale and consider why this is the case. Deaths per hundred of users can be a useful stat...if its not the unit at fault then the 'type' of instructor promoting them will be a give away. Ask an instructor via email who teaches regularly multiple units for some advice. Of course if they dont teach the unit your interested in then there opinion carries little weight. Aaron at Emperor teaches both the units you mention - im sure he could advise you in the right direction.

Forum advice is largely useless () there are more subtle adverts and pseudo gurus diving twice a month giving advice from their hardly extensive experience on the web than around any dive site.

If someone has more posts than dives then ignore them.

hope that helps...

jhaaja

Warning! Seriously OT!

Could it be so that Roger has checked his log to find the real hours?

JH

rogeringebo

Henrik is right, I mixed it up a little... To be honest, I am sloppy when it comes to logging my dives
Actually, I do not log at all any more, I estimate....
Before I was a full time dive instructor I did not log every time I got on the subway to work either or how many times I went for a run.
Diving CCR is not a huge event any more, its just part of what I do for a living.
If you really have to know I might be able to give you a accurate count of dives for the past week.
Now lets get back to the topic...

Best regards
Roger

rogeringebo

This is of course the best way to find out what you like best.
Get your own opinion and listen to people around you with real experience of more then one unit.
I know both Matt and Andy from my years in Thailand and both can give you valuable advice built on vast CCR experience.
What ever rebreather you choose its a million times better then diving open circuit

Best wishes
Rodge

Drmike

Hardly possibe to prove one way or the other! I can easily imagine stressed divers hyperventilating on poorly breathing units increasing retained CO2 and creating a huge cluster f_ck. From personal experience on poorly breathing units on deep or working dives I know which one is safer. Retained CO2 IS an important saftey factor. It clouds your judgement, more likely to make mistakes and induces panic. You are closer to that point pushing hard on a rebreather with a bad WOB than you are with one that doesnt. Diving a unit with a good WOB gives you a larger safety margin.

You buy a rebreather to breathe. How that rebreather breathes is very important. How efficently is enables you to exchange gas is critical to what its function is. How long and under what situations the scrubber lasts is also critical

I have done deep dives on homebuilds that apear to breathe nice - I could go around telling people that proves its capable of diving safely to these depths - and it is PROVIDED I dont have to work hard, or my RMV increases due to stress from a problem. Then all bets can be off. WOB isnt the only important factor - but it does provide a measure of how wide your safety margin is from having ventilation issues. Nice relaxing scooter dive with no stress - almost any unit will do almost any depth from a WOB viewpoint, but throw some work or stress in the mix and......


agreed CE mark does nothing for credibility/build quality, floodability of the system - it is very good though at indicating the breathing performance (which is afterall why we need them)

ah, something we agree on

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Cave diving is a sport
Wreck diving is a sport
Diving in general is a sport

'Rebreather diving' is not a sport
its the delusional obsession with a highly dangerous and often inappropriate piece of equipment

Gilles

Cannot contribute much about the Pelagian, other than it's light travel weight makes it a strong contender for a 2nd Rebreather.

I do significant travel with diving gear, and this is set to get worse (better? depends on how you look at it). The Meg is a very tough unit and can withstand the rigours of travel quite well. Other than cells, it has never let me down in spite of much travel related abuse. It is however, quite heavy (something like 30 Kg all rigged up, and around 20 for travel w/o tanks).

The 10Kg or so saving in an alternative unit would serve my failed surgery lumbar quite well.

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http://www.dirrebreather.com

Ben Field

I would suggest you ignore this entire post as it was afterall posted as Advice on a Forum...

Nothing wrong with diving twice a month either, 24days a year diving a certain rebreather gives that person 24 more days that someone without the rebreather- go figure how much that advice is worth...

My advice- go try both out. I wouldn't drop that amount of money or trust something I hadn't entirely stripped, rebuilt and test dived.

Just some useless info from someone with a couple more posts than dives

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