40cf? or 80cf?

Anders Knudsen · June 22nd, 2006, 06:02 PM

Hello Guys,

I know this is an odd post J but you have to help me decide what would be best buy.

I am going to buy another deco bottle, but what size? I don’t want another 7L because they are to heavy.

But a 40cf? or a 80cf ?

I am going to use it on deeper dives, 65m+ when I am using 2 or three bottles.
but I am hoping to do a 85m dive in the near future and I want this to be my final setup.

At the moment I am the lucky owner of :

2*15l steel
2*12l steel
7l alu
80cf alu.

What to do?
Should I buy a 40cf or a 80cf?

Tricky · June 22nd, 2006, 06:10 PM

If you don't want another 7l because it's too heavy, surely that also means an 80 would be too heavy?

**Howard Payne** · June 22nd, 2006, 06:14 PM

I have an AL40 and its a lovely cylinder to dive - you barely even notice it. I would have thought an AL80 as a backgas stage, 7l for 50% and Al40 as an oxygen bottle would be a good combination. I believe a number of the UK teams use that configuration with a lot of success. Needs someone more qualified than me to comment tho' really

caverkevin · June 22nd, 2006, 06:22 PM

Quote: (Originally Posted by Tricky)

If you don't want another 7l because it's too heavy, surely that also means an 80 would be too heavy?

He could mean in the water......

80's are nice if you don't mind the bulk and the weight out of the water. 80's ride really nice with only a partial fill. If you only get a partial fill, you will have loads more gas than a 40. If you are doing small dive and don't use much gas, the you can do a couple dives.

40's are small, light and easy. Sometimes there is just not enough gas.

Have you sat down to do the math for the amount of gas you will need for these dives? Figure out what you need to dive and how much pressure in each sized cylinder. Then figure out what works best.

One other thing! 80's are nice for single tank diving!!

Cheers!!

Kevin

vid · June 22nd, 2006, 08:18 PM

Quote: (Originally Posted by caverkevin)

40's are small, light and easy. Sometimes there is just not enough gas.

agreed

depends on how you want to use this extra cylinder(is it for just you or team bailout) and with what gas

with a 40 cf - assuming it's for 02 deco - you'll get about 20 minutes at 6M and 5 minutes to the surface, allowing for team bailout procedures - is that enough for your planned 80+M dives?

vid

TDave · June 22nd, 2006, 08:21 PM

Quote: (Originally Posted by Anders Knudsen)

At the moment I am the lucky owner of :

2*15l steel
2*12l steel
7l alu
80cf alu.

40cf.

No contest.

Judging by what you've got at the minute anyway, a 40 would be the perfect addition, allowing you to use it as the perfect O2 bottle on the deeper / longer dives, with the 7l as the 21m bottle and the 80 as bottom stage.

Also, as pointed out by others, the 40 is so light and easy to dive with that any shallower / shorter deco can be done using it as a 21m bottle.

Just my two pence

TD

Anders Knudsen · June 22nd, 2006, 08:23 PM

I have been doing the math, most of the dives are doable with an 40cf, and I like that it is rather small, but then if I would use an 80cf I would have shit loads of gas, especially now when I am starting to cave dive.

I think the best way, is to have a couple of dives with both configurations, and then decide.

Thanks for the fast replies, I know I should be figuring these things out myself, but as a student I don’t have the money to make mistakes.

Best regards

Anders Knudsen

davy · June 23rd, 2006, 11:47 AM

My default setup for 60+m dives is a 80cuft for 50% and 40cuft for O2.
A 40 would be enough for the 50%, but doesn't allow for much reserve... so I prefer the 80...
Also a partially filled 80 rides much better than a full (I don't like 80's full of nitrox, with 50/25 they ride good even when full)

I get about 30mins of O2 out of a 40 filled to 150 bar not including breaks, and gas to spare as reserve, so that will be one hell of a dive when I need more than that... (unless you do some kind of weird deco

)

If you plan on cave diving... 80's are standard since you can drop them... so that might be a better choice...
but I have used 40's for O2 many times.

If you get another 80, you can use one as a stage, another for 50% with plenty reserve and the 7 for O2?

Then again, you should try a 40 before you buy... they are so nice in the water

and unless your gas consumption goes throught the roof makes a perfect O2 bottle.

In the end you will end up with your garage packed full of tanks anyway

NIMROD CHEN · June 23rd, 2006, 02:43 PM

Quote: (Originally Posted by davy)

In the end you will end up with your garage packed full of tanks anyway

you can never have to many tanks

Tricky · June 23rd, 2006, 03:11 PM

Quote: (Originally Posted by NIMROD CHEN)

you can never have to many tanks

June 22nd, 2006, 06:02 PM	#1 (permalink)
Anders Knudsen(Offline) Gadevang Underwater Explorers Join Date: Dec 2005 Location: Denmark Posts: 182	40cf? or 80cf? Hello Guys, I know this is an odd post J but you have to help me decide what would be best buy. I am going to buy another deco bottle, but what size? I don’t want another 7L because they are to heavy. But a 40cf? or a 80cf ? I am going to use it on deeper dives, 65m+ when I am using 2 or three bottles. but I am hoping to do a 85m dive in the near future and I want this to be my final setup. At the moment I am the lucky owner of : 215l steel 212l steel 7l alu 80cf alu. What to do? Should I buy a 40cf or a 80cf? __________________ If someone standing on dry land tells you they're safe diving deep on air, give them a wide berth. If they're that stupid at 1 ATA, you know they won't get any smarter at depth

June 22nd, 2006, 06:10 PM	#2 (permalink)
Tricky(Offline) New Member Join Date: Nov 2005 Location: Reading, Berkshire Posts: 555	If you don't want another 7l because it's too heavy, surely that also means an 80 would be too heavy? __________________ "I know that you believe that you understand what you think I said, but I am not sure you realise that what you heard is not what I meant." "Make me one with everything" said the Mystic to the Hamburger vendor. Sigmastorm RPG - Play online now free! UK Diving Forum Sryth: A Free Online Text RPG Join the Adventure! Fallen Sword: Free online RPG

June 22nd, 2006, 06:14 PM	#3 (permalink)
Howard Payne (Online) Strokey Dokily Doo Join Date: Nov 2005 Location: London Posts: 1,210	I have an AL40 and its a lovely cylinder to dive - you barely even notice it. I would have thought an AL80 as a backgas stage, 7l for 50% and Al40 as an oxygen bottle would be a good combination. I believe a number of the UK teams use that configuration with a lot of success. Needs someone more qualified than me to comment tho' really __________________ The Foxturd Chimp

June 22nd, 2006, 08:21 PM	#6 (permalink)
TDave(Offline) New Member Join Date: Nov 2005 Location: Lancaster, UK Posts: 94	Quote: (Originally Posted by Anders Knudsen) At the moment I am the lucky owner of : 215l steel 212l steel 7l alu 80cf alu. 40cf. No contest. Judging by what you've got at the minute anyway, a 40 would be the perfect addition, allowing you to use it as the perfect O2 bottle on the deeper / longer dives, with the 7l as the 21m bottle and the 80 as bottom stage. Also, as pointed out by others, the 40 is so light and easy to dive with that any shallower / shorter deco can be done using it as a 21m bottle. Just my two pence TD __________________ Dave Smith

June 22nd, 2006, 08:23 PM	#7 (permalink)
Anders Knudsen(Offline) Gadevang Underwater Explorers Join Date: Dec 2005 Location: Denmark Posts: 182	I have been doing the math, most of the dives are doable with an 40cf, and I like that it is rather small, but then if I would use an 80cf I would have shit loads of gas, especially now when I am starting to cave dive. I think the best way, is to have a couple of dives with both configurations, and then decide. Thanks for the fast replies, I know I should be figuring these things out myself, but as a student I don’t have the money to make mistakes. Best regards Anders Knudsen __________________ If someone standing on dry land tells you they're safe diving deep on air, give them a wide berth. If they're that stupid at 1 ATA, you know they won't get any smarter at depth

June 22nd, 2006, 06:22 PM	#4 (permalink)
caverkevin(Offline) Doing It Caverkevin Join Date: Nov 2005 Location: North Kackilackie Posts: 363	Quote: (Originally Posted by Tricky) If you don't want another 7l because it's too heavy, surely that also means an 80 would be too heavy? He could mean in the water...... 80's are nice if you don't mind the bulk and the weight out of the water. 80's ride really nice with only a partial fill. If you only get a partial fill, you will have loads more gas than a 40. If you are doing small dive and don't use much gas, the you can do a couple dives. 40's are small, light and easy. Sometimes there is just not enough gas. Have you sat down to do the math for the amount of gas you will need for these dives? Figure out what you need to dive and how much pressure in each sized cylinder. Then figure out what works best. One other thing! 80's are nice for single tank diving!! Cheers!! Kevin

June 22nd, 2006, 08:18 PM	#5 (permalink)
vid(Offline) New Member Join Date: Nov 2005 Location: london/surrey border, UK Posts: 353	Quote: (Originally Posted by caverkevin) 40's are small, light and easy. Sometimes there is just not enough gas. agreed depends on how you want to use this extra cylinder(is it for just you or team bailout) and with what gas with a 40 cf - assuming it's for 02 deco - you'll get about 20 minutes at 6M and 5 minutes to the surface, allowing for team bailout procedures - is that enough for your planned 80+M dives? vid

June 23rd, 2006, 11:47 AM	#8 (permalink)
davy(Offline) DIveR Join Date: Nov 2005 Location: Belgium Posts: 277	My default setup for 60+m dives is a 80cuft for 50% and 40cuft for O2. A 40 would be enough for the 50%, but doesn't allow for much reserve... so I prefer the 80... Also a partially filled 80 rides much better than a full (I don't like 80's full of nitrox, with 50/25 they ride good even when full) I get about 30mins of O2 out of a 40 filled to 150 bar not including breaks, and gas to spare as reserve, so that will be one hell of a dive when I need more than that... (unless you do some kind of weird deco ) If you plan on cave diving... 80's are standard since you can drop them... so that might be a better choice... but I have used 40's for O2 many times. If you get another 80, you can use one as a stage, another for 50% with plenty reserve and the 7 for O2? Then again, you should try a 40 before you buy... they are so nice in the water and unless your gas consumption goes throught the roof makes a perfect O2 bottle. In the end you will end up with your garage packed full of tanks anyway

June 23rd, 2006, 02:43 PM	#9 (permalink)
NIMROD CHEN(Offline) New Member Join Date: Mar 2006 Location: ISRAEL Posts: 88	Quote: (Originally Posted by davy) In the end you will end up with your garage packed full of tanks anyway you can never have to many tanks

June 23rd, 2006, 03:11 PM	#10 (permalink)
Tricky(Offline) New Member Join Date: Nov 2005 Location: Reading, Berkshire Posts: 555	Quote: (Originally Posted by NIMROD CHEN) you can never have to many tanks __________________ "I know that you believe that you understand what you think I said, but I am not sure you realise that what you heard is not what I meant." "Make me one with everything" said the Mystic to the Hamburger vendor. Sigmastorm RPG - Play online now free! UK Diving Forum Sryth: A Free Online Text RPG Join the Adventure! Fallen Sword: Free online RPG Last edited by Tricky; June 23rd, 2006 at 03:11 PM. Reason: Oops, wrong tags