500 psi for two divers?

[diver 85]

Probably not----------but who's counting @ this stage........Blow & Go if need be, but get to the surface........Probably greater chance of surviving on top than no air --down below.....

 

[tbone1004]

PhatD1ver, you don't actually understand the math, you just looked at the numbers. If you actually ran the math for what I posted you would realize that those numbers include BOTH divers breathing off of diver A's tank and what diver B has for air is not even a factor. This calculation needs to be done before EVERY dive and needs to include what tank you have, what your historical SAC average is multiplied by 1.5 for planning, what your buddies historical SAC is x1.5 *if you don't have that, it is safe to assume 1.2 for planning*, what the max potential depth is *i.e. what is the bottom depth, not your planned depth*, and whatever tank you have. The numbers change on every new dive site, so it has to be done.

Tatiana, what you are experience is insufficient instruction. You should never have been certified if you don't understand these concepts. Before PADI dumbed the whole thing down, the original goal of the open water certification was for divers to safely execute dives with only their buddy, there was no divemaster bullsh!t, no babysitters in the water, just you and your buddy. If you are not able to safely plan and conduct a dive with only you and your buddy, the instructor shouldn't have ever certified you. It's not your fault, and we are trying to explain how to fix it.

 

[EFX]

fire_diver has outlined a good dive plan. Another "rule-of-thumb" for deep dives below 60 ft. is to start your ascent when tank pressure gets to depth x 10. So for a 90 ft. dive begin ascending at 900 psi. This should be considered a minimum and I'm not suggesting this should be substituted for more meticulous or conservative dive plans. With experience you'll know what you need. Don't forget going over equipment and hand signals with your buddy: how do the weights release, where is the alternate air source, etc. Hand signals vary so go over them: remaining air, ascend vs. surface now, safety stop, wait or stop, boat, anchor line, etc.

 

[TSandM]

Tatiana, you came and asked a very good question, and one which your open water class did not prepare you to answer, as most open water classes do not.

There are tools to allow you to answer this question, and quite a few people above have pointed you to those tools. In addition, your question has been answered, with the calculations to show the basis for that answer.

The responses are getting testier, and there is a reason for that. The attitude of, "I don't have to plan my dive, I'll just follow the DM," is one that gets people into trouble all the time. I highly suggest spending an hour or so reading stories from the "Near Misses" subforum. You will see stories of people signaling dive guides that they are low on gas and being ignored. You will see stories of people being led below the limits they agreed upon before the dive, and people being led into overhead environments for which they were unprepared. You simply CANNOT assume that the person leading your dive will do the work you ought to be doing to ensure your safety.

Dive planning, especially if what you are doing is diving off warm water charter boats, isn't very complicated. The dive briefing should give you a basic description of the site, and idea of the planned depths, and a mention of any hazards. You have only one kind of tank to sort out, and that's the standard Al80. It's easy to remember that that tank has 2.5 cubic feet in every 100 psi of gas. Pick a rule of thumb for gas reserves -- HERE is a cheat sheet that uses a standard PADI ascent as a model -- and agree with your buddy that you will start your ascent at that point. Stick to your guns! A quick discussion of hand signals, buddy separation protocols, and how you share gas will be a pretty good dive plan for the kind of diving you appear to intend to do.

You are getting harsh answers because your responses worry us. Ceding responsibility for your dive gets people into trouble, sometimes serious trouble. We are trying to encourage you to step up and become a strong and independent diver. You will have more fun, be safer, and stay in the sport longer that way.

 

[TatianaSilva]

PhatD1ver, you don't actually understand the math, you just looked at the numbers. If you actually ran the math for what I posted you would realize that those numbers include BOTH divers breathing off of diver A's tank and what diver B has for air is not even a factor. This calculation needs to be done before EVERY dive and needs to include what tank you have, what your historical SAC average is multiplied by 1.5 for planning, what your buddies historical SAC is x1.5 *if you don't have that, it is safe to assume 1.2 for planning*, what the max potential depth is *i.e. what is the bottom depth, not your planned depth*, and whatever tank you have. The numbers change on every new dive site, so it has to be done.



Tatiana, what you are experience is insufficient instruction. You should never have been certified if you don't understand these concepts. Before PADI dumbed the whole thing down, the original goal of the open water certification was for divers to safely execute dives with only their buddy, there was no divemaster bullsh!t, no babysitters in the water, just you and your buddy. If you are not able to safely plan and conduct a dive with only you and your buddy, the instructor shouldn't have ever certified you. It's not your fault, and we are trying to explain how to fix it.

so what about divers that are not certified but have been diving many many times ? im lost ... i thought if you are not taking courses you can still dive ? i guess they wont explain how to plan a dive if you wont take any course but you can still dive ?

 

[tbone1004]

the certification cards are required for gas fills at every commercial shop that I have ever been to. If you own your own equipment, own your own compressor, etc there is no one stopping you. My very few C-cards, Nitrox, Rescue, Full Cave, AI, allow me to get gas fills when I need them and to get onto commercial dive boats.

If you are at a resort and they allow you to dive without certification, there is a huge liability risk if something happened to you, but if you have a C-card that says "Diver" from any of the major agencies, the assumption is that you are able to plan your dive safely. Unfortunately many of the agencies are proud to go from new diver to instructor in less than a year, and their instructors don't actually understand all of the science behind dive planning. I was spoiled because I had a semester long class at university to teach all of the fundamentals of proper diving and unfortunately in the US there is only a small handful of universities that actually have their OW divers come out and look like real divers and think like real divers.

I dont fully understand what you are getting at in the last line of your comment, so if you could clarify that would help.

 

[redacted]

so what about divers that are not certified but have been diving many many times ? im lost ... i thought if you are not taking courses you can still dive ? i guess they wont explain how to plan a dive if you wont take any course but you can still dive ?

Taking a course is one way to learn about dive planning. For many divers, it is not the only way.

 

[tursiops]

so what about divers that are not certified but have been diving many many times ? im lost ... i thought if you are not taking courses you can still dive ? i guess they wont explain how to plan a dive if you wont take any course but you can still dive ?

Sorry, I do not understand what you are saying here.

 

[boulderjohn]

Tatiana, what you are experience is insufficient instruction. You should never have been certified if you don't understand these concepts. Before PADI dumbed the whole thing down, the original goal of the open water certification was for divers to safely execute dives with only their buddy, there was no divemaster bullsh!t, no babysitters in the water, just you and your buddy. If you are not able to safely plan and conduct a dive with only you and your buddy, the instructor shouldn't have ever certified you. It's not your fault, and we are trying to explain how to fix it.

How has this changed?

The OW course has never advicated following the DM as a way to plan a dive. It isn't even mentioned. The course includes all the steps required to plan and execute a dive. In the OW checkout dives, students have always supposed to have been involved with planning each dive. In the new version of the course, the OW students must even plan and execute the last entire OW dive on their own, with the instructor only going along as an observer to make sure things are OK.

 

[TatianaSilva]

I mean Ive seen people diving at resorts who went to open sea, dive in the same places as I did and werent taking part in any course. I dont think those people knew how to plan a dive ?
Anyway, Im planning a trip to Tenerife or Mallorca in September as I havent been diving since I did the OW. Ive been speaking with some dive centres in both places and explained my newbie situation . I am going to try and plan the dives with my buddy but I certainly wont rely completely on them I have no problems with weight check, buoyancy, breathing or even being low on air but I still need to learn how to use the computer and have someone who is supposed to know about this around me to make sure everything is fine . I know you are all care about other divers but its too soon for me to think im able to plan dives just because i have the OW when 2 months ago i didnt even know i was going to ever try diving ... its lots of info to take guys ! give me a break but obviously, thanks to all , im already working on this