New Divemaster air consumption

[scubadada]

Hi @Orenda

There is a long thread in Basic Scuba discussing average gas consumption Average Gas Consumption If you haven't already found it, you may enjoy reading it. There are several discussions in the thread regarding measures to help reduce your gas consumption, many have already been mentioned in this thread

As others have pointed out, it would be valuable to know your current average gas consumption. SAC is measured in pressure/min/atm and is cylinder size dependent (reported as psi/min in imperial). RMV is measured in volume/min/atm and is cylinder independent (reported as cu ft/min in imperial). To make these calculations you need your start and end pressure, average depth, and total dive time. RMV will also require your cylinder gas volume and service pressure.

You haven't mentioned the dive computer you use. Most computers will give you at least dive time and avg depth, either in the on board or downloaded log. You would need an air integrated computer to capture your start and end pressure. Many AI computers will also calculate SAC, many, but not all, RMV also. If your computer is not AI, you simply write down your pressures on a slate or wet notes.

Following your RMV will give you an idea of progress you have made in your gas consumption. Once you know your average RMV, you can use the information to estimate the gas you would need to execute any profile you will be diving. Say you want to execute a 50 min dive with an average depth of 50 ft and that your RMV is 0.8 cu ft/min (on the high side of the distribution). This dive would require a touch over 100 cu ft of gas. You would probably want something like 120 cu ft of gas, a HP120 steel tank would work for example.

Best of luck in your diving

 

[Saltwater_Parrot]

150-200 per dive? Are you hiring a guide every time you go down? $60 ish for a full kit and $10 for the second tank... maybe do self reliant/solo cert so you can get more time below without the restraints of terrible and expensive buddies

Not sure where you are diving, but a normal charter with no guide is going to cost you $150ish at the minimum in Florida (thats with all personal gear besides tanks). With a guide, that can easily go into $250-300+ territory. My cheapest dive so far, in Florida, has been about $125, which was just a mile or so from shore.

Of course, if you have friends with boats, then you don't need to go out on charters, but there aren't exactly tons of divers with big boats willing to let anyone hop on.

 

[scubadada]

Not sure where you are diving, but a normal charter with no guide is going to cost you $150ish at the minimum in Florida (thats with all personal gear besides tanks). With a guide, that can easily go into $250-300+ territory. My cheapest dive so far, in Florida, has been about $125, which was just a mile or so from shore.

Of course, if you have friends with boats, then you don't need to go out on charters, but there aren't exactly tons of divers with big boats willing to let anyone hop on.

I frequently use 5 different charters out of Boynton Beach, West Palm, and Jupiter, FL. The cost for a 2-tank dive with 2 AL80 nitrox tanks is between $135 and $150. Then there's the tip, usually $20, total cost $155-170.

 

[DiveProKoko]

Thank you everyone. All good responses. I know my consumption will go down the more I dive/become more and more comfortable and conscious, when I started I was maxing 30-40 mins at 30 feet lol. Guess I’m wondering how much longer I will be able to dive after more experience, and if there are other DMs here that have the same problem.

You'll get better with more experience. And make sure your weight is good. Also, a little trade secret...Some DM's that suck gas often run an HP100 tank over an AL80

 

[DiveProKoko]

Ok, before this becomes an argument, yes, I understand I’m a new diver, especially compared to all of you. That’s why I posted a question. I’m beginning the DM course with only 47 dives under my belt, but I’m not doing this for ego. I left my stressful job and moved to Florida. As a turn of fate I discovered scuba and am obsessed. But have no dive buddies, it costs me $150-200 to get a dive in, and I’ve spent thousands on classes and equipment. The local dive shop has offered me the job of running a 30 ft shore dive (close to EMS, no current) when I finish DM because they like me and think my skills are good. I agree instructor should wait, but this will give me the ability to dive free, make a little income at the same time. Sorry if you disagree, but it’s the best opportunity I’ve had in my life. I love people and love seeing the face on new divers, or after a new site. Just wanted some advice.

Dude, it doesn't matter if you have 47 dives or 470 dives. If you're good enough to do the job, go do it!

 

[DiveProKoko]

I don't mean to be rude, but I have not thought of a better way to ask this......

What dive shop has offered you this job when you have so little experience? I am not trying to be rude or be mean. I really do want to know for my own safety. I am planning a trip to Florida to dive and want to make sure that I do not use that shop........... I should not have to ask to see the log book of the DM in charge of my dive.

That's a fair concern. However, depending on how many guided dives you've been on, would you know how many dives the DM has if he/she didn't tell you? I would offer that you if you've dove enough, you have done dives with DMs that have less than 100 dives before and likely never knew it or questioned it as long as he/she did a good job. I'll concede that dive number can give you insight into experience. But keep in mind, there are good DMs out there with 100 dives (or less) and DMs with 1 dive a hundred times over. Dive operators don't hire/keep the latter.... Happy diving!

 

[Blackcrusader]

I do expect my DM in charge to have a lot more experience than I do. I should not have to ask to see the log book of the DM in charge of my dive.

If I was like that was then I would not be diving with a lot of dive centers in Asia. There are always people doing DM courses with less diving experience than I have. I have dived with DM's that are newly certified. I never ask to see their log books. You as a diver should not rely on the DM but be happy they are there to assist if you have an issue. Real life experiences I have those but many new DM's do not. The DM would have rescue cert and have recent EFR.

I have dived with new instructors who have less experience than I have. New DM's I have seen some tend to over monitor the dive group and then find out they are the one running low on air as they have done too much checking of divers.

I would dive with this chap doing his DM course now. The dive center would say hey we are doing very shallow dives with a new DM and OW certs would you care to join that dive. I've done this many times. Then the DM can pair me up with a diver. This does not bother me at all. If I want to do deeper dives to say 35m then I ask to be assigned to a group doing deeper dives.

I believe the OP should really do some more diving and gain experience. His high air consumption is a worry as he has to be able to have enough air to share with other divers in an emergency.

The OP has found a passion for diving. That's great as he will be wanting to learn things and he wants to improve his skillset. To do that he needs more diving. Working as a DM will get him a lot more dives than maybe he can afford to pay for as a customer.

 

[Blackcrusader]

I'm 6'5" and well north of 250. I'm also a DM and photographer. If you want to be a DM, be a DM. I started the DM with maybe 150 dives, and I felt like that was enough experience to begin. I did a lot of quarry work, pool work, and shadowing instructors before I did things on my own. When you're leading dives, you are assuming some level of responsibility. Let your conscience guide you and live up to any responsibility you commit to. If you're unsure of a situation, don't take people out.

In terms of your actual question, it took me a good long while before my air consumption got good. Proper weighting, proper trim, and proper buoyancy are all very important. My photography actually helped me develop those skills. I wanted to be able to hover 6" above a subject and not touch anything. Several hundred dives later, and I can do that. Now I can lead a dive and photograph the people on the dive and be the last one back on the boat. But it took years.

There's lots of good advice here, but the biggest thing that I've observed is what @BLACKCRUSADER said - and that's being relaxed. I think I'm relaxed in the water, but the people I've observed who are best on air are completely Zen in the water. One frog kick every 30 seconds. No body/arm movement. No fidgeting with gear. I've seen it in resort dive staff as well - people who have 5,000 dives. They barely move unless needed. They sip air, and they come up with half a tank when everyone else is at 50bar.

Good luck and enjoy the journey!

I think the OP is not a relaxed diver yet. I have found divers with high air consumption usually have not got mastered buoyancy, do mask clearing often, and often move around a lot or chase the marine life. I've helped people who dive with me over a few days to improve their buoyancy and learn to slow down and then they are wow, I have so much more air than before.
One of my "zen" dives I like to boast about was the last dive of a vacation with a DM and OW divers so we did a max 20m but most of the dive was quite shallow around 11m. DM has the divers back to the boat after 50 minutes for the safety stop and several of the OW divers were down to 40 bar back on the boat. I was in that sipping my air letting the very slow current carry me along not needing to fin or move except when I wanted to take a video or photo. Back on the boat with 140 bar lol. Tell you the truth it is the lowest sac rate I ever had on a dive. 7.18l/min

The OP will get there.

 

[Blackcrusader]

Hi @Orenda

There is a long thread in Basic Scuba discussing average gas consumption Average Gas Consumption If you haven't already found it, you may enjoy reading it. There are several discussions in the thread regarding measures to help reduce your gas consumption, many have already been mentioned in this thread

As others have pointed out, it would be valuable to know your current average gas consumption. SAC is measured in pressure/min/atm and is cylinder size dependent (reported as psi/min in imperial). RMV is measured in volume/min/atm and is cylinder independent (reported as cu ft/min in imperial). To make these calculations you need your start and end pressure, average depth, and total dive time. RMV will also require your cylinder gas volume and service pressure.

You haven't mentioned the dive computer you use. Most computers will give you at least dive time and avg depth, either in the on board or downloaded log. You would need an air integrated computer to capture your start and end pressure. Many AI computers will also calculate SAC, many, but not all, RMV also. If your computer is not AI, you simply write down your pressures on a slate or wet notes.

Following your RMV will give you an idea of progress you have made in your gas consumption. Once you know your average RMV, you can use the information to estimate the gas you would need to execute any profile you will be diving. Say you want to execute a 50 min dive with an average depth of 50 ft and that your RMV is 0.8 cu ft/min (on the high side of the distribution). This dive would require a touch over 100 cu ft of gas. You would probably want something like 120 cu ft of gas, a HP120 steel tank would work for example.

Best of luck in your diving

He can also download diving log.com and enter the starting and ending pressure and get the sac rate shown that program as well. Or learn to manual calculate using tank volume.

 

[SlugLife]

Not sure where you are diving, but a normal charter with no guide is going to cost you $150ish at the minimum in Florida (thats with all personal gear besides tanks). With a guide, that can easily go into $250-300+ territory. My cheapest dive so far, in Florida, has been about $125, which was just a mile or so from shore.

Of course, if you have friends with boats, then you don't need to go out on charters, but there aren't exactly tons of divers with big boats willing to let anyone hop on.

You'll often pay that for a dive-charter, but there are ways to dive without a dive-charter.