First dive at 40 meters - Newbies recreational
- Thread starter Dody
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Good idea... diving should be about exploring the scene, not about challenging limits just to see if everything will go according to plan.
Also good... the "40 meters" thing is so shrouded in mystery for new divers, it's good to get there (safely) and realize that it's just as wet as the water at 10, 20 or 30 meters. No reason to go again, unless there is something to see.
OP
Dody
Contributor
When I read that I thought "how long before someone posts 'kneeling on the bottom' ?" As usual, did not take long or disappoint.
Hey now, technically I was second. I'm not one to criticize for kneeling on sand, I just thought the juxtaposition of kneeling and "buoyancy control ok" was amusing.
I'm assuming the DM was being supervised by your Deep Diver instructor and the instructor was somewhere nearby? I'm PADI, so I don't know the SSI course.
Please don't take judgement at all on the following as I'm always interested in various courses around the world. But I'd personally be concerned with aspects of the dive. I'm glad you're writing about it and hope you had a debrief with your wife and DM about how it could have gone better and what you learned. For example:
- going past decompression limits on a training dive.
- was there discussion on emergency deco procedures, or was the computer to be followed? PADI has specific guidelines on dealing with emergency deco, I assume SSI as well. What would you do on computer failure?
- you say you spent time at 20m, approximately 10 minutes. This would eat into your overall NDL at 40m, which would already be about 10 minutes with a normal straight descent, and of course, your air reserves.
- could the DM have kept to the plan and NDLs better?
- sounds like your descent was too slow and your ascent not fast enough. Can you confirm that with your dive log? A dive to these depths needs execution and skills not far off from tech diving, so you got a taste of what's needed and what can happen if you're off.
- separation of team members - the DM seems to have been at different depths and maybe not available to help during the strong current
- that some of the feelings you described during the ascent were likely narcosis induced
- some form of depth buffer, like planning for 37m (120') instead of 40m/130' (more a comment on how an instructor might build in some conservatism based upon the site or conditions)
The good points were that you finished the dive, dealt with a bit of a scare that worked out, stayed calm and in control, followed the computer guidance instead of bolting to the surface, and added conservatism to the safety stop. Congratulations and thanks for sharing!
Please don't take judgement at all on the following as I'm always interested in various courses around the world. But I'd personally be concerned with aspects of the dive. I'm glad you're writing about it and hope you had a debrief with your wife and DM about how it could have gone better and what you learned. For example:
- going past decompression limits on a training dive.
- was there discussion on emergency deco procedures, or was the computer to be followed? PADI has specific guidelines on dealing with emergency deco, I assume SSI as well. What would you do on computer failure?
- you say you spent time at 20m, approximately 10 minutes. This would eat into your overall NDL at 40m, which would already be about 10 minutes with a normal straight descent, and of course, your air reserves.
- could the DM have kept to the plan and NDLs better?
- sounds like your descent was too slow and your ascent not fast enough. Can you confirm that with your dive log? A dive to these depths needs execution and skills not far off from tech diving, so you got a taste of what's needed and what can happen if you're off.
- separation of team members - the DM seems to have been at different depths and maybe not available to help during the strong current
- that some of the feelings you described during the ascent were likely narcosis induced
- some form of depth buffer, like planning for 37m (120') instead of 40m/130' (more a comment on how an instructor might build in some conservatism based upon the site or conditions)
The good points were that you finished the dive, dealt with a bit of a scare that worked out, stayed calm and in control, followed the computer guidance instead of bolting to the surface, and added conservatism to the safety stop. Congratulations and thanks for sharing!
Barnaby'sDad
Contributor
Blackcrusader
Contributor
This would be a good dive to enter your log into divinglog.com where you can enter your tank size the amount of air you started at and your end of 40 bar. You save that information and then the software works out your sac rate for that dive. When I posted my dive log to retrieve a dropped camera at 45m you can see it's really descend quickly and watch NDL. I was fortunate the camera was easy to location find from where the lass who dropped it said where she dropped it. Yes sometimes people take too long to descend and then when they get deep the NDL time is almost done.
You wrote this below....
I made a very quick calculation (worst case scenario, we consume 5 times our SAC. 5x11 l/min round to 12, it is 60 l/min. with 150 bar that is 1800 liters, we have 30 min so no need to panic)
After you enter your 200 bar start and 40 bar end for a 40 minute dive you might find your sac rate is much higher then you think. You said your sac was 20L/m but you got down to 11l/min after a few dives. But that can change on any dive and calculations go out the window very easily.
What you should do is calculate your SAC for all your dives and see what the average is. I did for my last 200 dives to get a good overall understanding of my average sac rate.
Now we can add you to this thread Recreational Scuba Deco Diving
You wrote this below....
I made a very quick calculation (worst case scenario, we consume 5 times our SAC. 5x11 l/min round to 12, it is 60 l/min. with 150 bar that is 1800 liters, we have 30 min so no need to panic)
After you enter your 200 bar start and 40 bar end for a 40 minute dive you might find your sac rate is much higher then you think. You said your sac was 20L/m but you got down to 11l/min after a few dives. But that can change on any dive and calculations go out the window very easily.
What you should do is calculate your SAC for all your dives and see what the average is. I did for my last 200 dives to get a good overall understanding of my average sac rate.
Now we can add you to this thread Recreational Scuba Deco Diving
Blackcrusader
Contributor
Actually a good thing. If in a down current next to a wall actually the best thing is to get to that 45 degree angle and swim away from the wall into open water as the down current will decrease as you get distance from the wall. Putting air into your BCD in a down current also helps as some down currents are not super strong and using your BCD is what it is designed for. Just think of the down current as extra weights. Of course as you ascend you can dump air as required. We all need these experiences on dives to help us build up knowledge so we don't panic when in a stressful situation.
If you use the BCD to do your ascent you don't need to exert yourself and use fins to guide direction rather than have to swim up. Less swimming less air consumption.
Similar threads
