Dolphin for Rec diving?

scubastud16

Hey guys, I posted my intro thread yesterday, and now I have some specific questions.

I have always been interested in Rebreather's, and now I finally have to opportunity to learn about and experience them.

My family, friends, buddies, etc. (as well as myself, for the time being) dive OC. I know no one personally who dives with a Rebreather. I have the opportunity to have "demo" sessions in the pool and open water with a Dolphin, which I will almost certainly jump on to try it out.

My question to you is, will I be able to dive regularly with my girlfriend, brother, and parents on OC while I'm on an SCR? Will getting the fills be hard (over 40% EANx)? How about getting the scrubber?

Lastly, I'm all about tooling around and playing with my "toys" (car nut and engineering student), but I've been told Rebreather's need a lot of attention, which I will expect, but will I have to spend hours pre- and post-dive cleaning this thing?

Thanks a ton!

Danny

Gary Gressett

Not a bad option. I suggest you get trained. Rent a Dolphin and see what you think of Rebreather diving. Make an informed decision based on training and experience. But most of all, have fun and be safe.

Welcome to the Rebreather world.

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G squared

scubastud16

Oh don't worry, I plan on getting trained. I just wanted to see what the "experts" thought based on my diving experience, plans, and type of diving I do/intend to do.

Thanks for the welcome and the fast response!

Danny

Freef

The Dolphin needs broadly the same pre and post dive care as any Rebreather. Packing the scrubber is very, very important, as is monitoring your pO2 level throughout the dive. The CMF SCR [Constant Mass Flow Semi Closed Rebreather] system supplies a continual flow of nitrox into the loop, and you use part of the oxygen. Excess gas bubbles off through the overpressure valve.

It's a simple system with passive monitoring of the pO2-the electronics do not control the amount of O2 in the loop. A scrubber fill will last 3 hours, a full 5L of 60% will last a little over two with a reserve.

I dive with OC users on my Dolph. Realistically the maximum depth on nitrox is 40m. You will be comitted to the same decompression as if you had the gas you are breathing that particular nitrox mix OC [this is the mix in the loop, NOT the cylinder].

With a bit of practice you will be able to assemble the unit, including all checks and scrubber fill in 20-30 minutes from a box of bits. Cleaning takes longer, but a lot of that is soaking time.

Scrubber and nitrox should be obtainable where you are.

The Dolph is simple and robust, there are a lot of users and units out there.

There are ways of tuning the gas mix for better duration, but this is somethign to worry about after you have completed your training and have time on the unit.

Any more specific questions are better asked on the SCR forum, or you can contact me via the PM or email options. Asking on the forum is better though as you will get more replies and might ask a question that no one else has.

Welcome to rebreather world.

__________________
David.

Currently owner of two differently sized ankles.

fireman

Go straight to CCR.

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Heres to you Capt. Bill
Never Forget, and stay safe everyone.

scubastud16

I like my baby steps.....

I have no means of achieving IANTD Adv. EANx/Deco procedures certifications, and no means of buying a CCR (manual or electronic). Buying a Dolphin is going to expensive enough as it is! While I appreciate your advice, and I read just as much about CCR as I do about SCR, it's not really even possible for a college student like myself at the moment.

cramerdn

I was in the same situation and did the same thing. No regrets here.

I did use a 50 cu tank on my Dolphin specifically to cater to OW divers. The 27 cu ft tanks lasts about 1.5 normal open water dives but the 50 is good for two. So one fill survives two boat dives with OW dive buddies using 40%. 40% works well because you have reasonable parity with normal OW diver's depths and 40% is within the limits of normal nitrox cert so you have less arguments with fill stations about higher mixes, even though you are certified for up to 60% even with PADI.

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"Its better to live one day as a tiger than an entire life as a worm."

"But who's ever heard of a worm skin rug?"

Freef

Ah, the joys of those who don't see the point of the OP.

Of course it is possible to dive CCR with OC divers, but with themuch shorter decompression times and/or longer no deco times that CCR gives you, you are less likely to want to stay with your OC buddies. SCR gives you the same deco requirements as someone on OC using the equivalent gas, so you won't be hacked off waiting for them when your deco is finished.

Also a Dolphin can be converted to CCR in the future, or a second hand Dolph can be resold for about the same as you paid for it if you decide to buy a different unit.

__________________
David.

Currently owner of two differently sized ankles.

Beanie

Or longer

Hey the extra time hanging with OC buddies on CCR is called safety factor

Back to the OP
I don't dive a dolphin but I can't see maintenance being that much more than CCR which isn't that much really.
Set up and strip down time isn't hours, you'll find this out when you do the course or do a try dive on one.

Best course of action is to go get a dive on one and get whoever to show you the set up and strip down of it so you can gauge for yourself the time taken.

__________________
Beanie
Gallery Admin & Library Assistant.
www.outlawdivers.org.uk
www.beandiving.co.uk
www.beanengineering.co.uk
www.divelife.co.uk

scubastud16

Thanks for the help everyone!

Don't get me wrong, CCR really interests me, but it just isn't a possibility at the moment.

Next Wednesday night I'll be doing my first closed water dive on a Dolphin...wooo!!!!