As most have said 30 is the standard. Padi was on of the last to change to 30. It is very confortale to do and if you do exceed it , know that you have no need to panic by hitting 60. It was done all the time and if truth was told it is still done by those that learned 60. When you take the course remember the 60 in the material and ask what you should answer at test time 60 or 30. It wont make any difference cause you dont fail. I believe the requirement is that you get it right or know why you got the question wrong. hmmmm. You will be ok, get all you can from the course and enjoy diving. ONe more thing ... dont be a stranger on SB, there is a lot to learn here.
Who should I listen to?
- Thread starter ARDory
- 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
kwinter
Contributor
Victor is right. You can easily ascend at 60 fpm or even more if you're deep because you are not decreasing pressure by as big a factor as you are shallow. I will do 60 fpm below about 150 feet, 30 fpm from there to about 90 feet, and 20 fpm from there up to 20 feet. Then very slowly for the last 20 feet.
Read the book, take the quizzes, if your question is not answered, ask it during the class and keep asking until you get an explanation. If I am not mistaken that is why you take the class. Your BF is right, and it is right for you to question the answer you found on the DVD.
WhiteSands
Contributor
- Messages
- 668
- Reaction score
- 79
- # of dives
- 200 - 499
DevonDiver
N/A
A few points to consider:
1) Different agencies use different models for their dive planning. These models are based on algorithms have varying goals. The PADI model is calculated upon a maximum ascent speed of 18m/60ft per minute. Other agencies use 9m/30ft per minute, as do most dive computers.
2) Differences in agency/computer-stated ascent rates have historical explanations. Early tables were derived from the US Navy or Royal Navy tables - ascent rate (quick exit from the water) was a tactical consideration. It is not a tactical consideration for recreational divers. Tables/ascent speeds also varied according to the dive parameters that they covered - PADI's tables were exclusively written (not derived from the Navy tables) with recreational diving in mind - multiple dives per day with relatively short surface intervals and stringent limits on depth/time to maintain a comfortable barrier against unreasonable levels of DCS risk. Ascent rates factor against necessary off-gassing of absorbed nitrogen (decompression) - the schedule of ascent varies according to the amount of nitrogen absorbed. PADI theorized, then statistically proved, that 18m/60ft per minute was sufficient for off-gassing within the parameters of their dive tables (nitrogen that can be absorbed on a dive within PADI tables limits).
3) Other methods of dive planning; different tables, dive computers, laptop software, will have different parameters for nitrogen absorption - long/deeper/multi-level etc. That is especially true with decompression (technical) diving. This may result in a slower ascent rate, or even staged stops on ascent.
4) There is a significant difference between a maximum stated ascent speed and an optimum ascent speed. Most PADI divers are educated on the maximum ascent speed, but further trained to ascend slowly from every dive. Most instructors will use 9m/30ft per minute - in line with their dive computers. Too slow ascent can, arguably, be detrimental also, depending on the dive parameters - 'slower is better' is not a universal constant. But slower than 18m/60ft per minute is good advice nonetheless... that's just an absolute maximum limit.
5) Understanding a maximum permissible ascent speed can be beneficial - for instance; in emergencies when you need to surface quickly - especially on a CESA (Controlled Emergency Swimming Ascent). This is a factor considered when PADI determined their own maximum ascent rate. Recreational/Open Water diving places great emphasis on having immediate/swift access to the surface as a contingency for emergencies whilst diving.
6) When doing exams/quizzes, answer the question you are asked. If the question asks for a maximum ascent speed recommended by that agency, then supply that. If you supply a different answer, you will get the question wrong...and fail.
For a really good insight into ascent speeds, stops, dive tables and computers... do read Mark Powell's 'Deco for Divers'. Your boyfriend, as a prospective technical diver, would love reading that book too...
Article: Best Ascent Speed for Scuba Diving
1) Different agencies use different models for their dive planning. These models are based on algorithms have varying goals. The PADI model is calculated upon a maximum ascent speed of 18m/60ft per minute. Other agencies use 9m/30ft per minute, as do most dive computers.
2) Differences in agency/computer-stated ascent rates have historical explanations. Early tables were derived from the US Navy or Royal Navy tables - ascent rate (quick exit from the water) was a tactical consideration. It is not a tactical consideration for recreational divers. Tables/ascent speeds also varied according to the dive parameters that they covered - PADI's tables were exclusively written (not derived from the Navy tables) with recreational diving in mind - multiple dives per day with relatively short surface intervals and stringent limits on depth/time to maintain a comfortable barrier against unreasonable levels of DCS risk. Ascent rates factor against necessary off-gassing of absorbed nitrogen (decompression) - the schedule of ascent varies according to the amount of nitrogen absorbed. PADI theorized, then statistically proved, that 18m/60ft per minute was sufficient for off-gassing within the parameters of their dive tables (nitrogen that can be absorbed on a dive within PADI tables limits).
3) Other methods of dive planning; different tables, dive computers, laptop software, will have different parameters for nitrogen absorption - long/deeper/multi-level etc. That is especially true with decompression (technical) diving. This may result in a slower ascent rate, or even staged stops on ascent.
4) There is a significant difference between a maximum stated ascent speed and an optimum ascent speed. Most PADI divers are educated on the maximum ascent speed, but further trained to ascend slowly from every dive. Most instructors will use 9m/30ft per minute - in line with their dive computers. Too slow ascent can, arguably, be detrimental also, depending on the dive parameters - 'slower is better' is not a universal constant. But slower than 18m/60ft per minute is good advice nonetheless... that's just an absolute maximum limit.
5) Understanding a maximum permissible ascent speed can be beneficial - for instance; in emergencies when you need to surface quickly - especially on a CESA (Controlled Emergency Swimming Ascent). This is a factor considered when PADI determined their own maximum ascent rate. Recreational/Open Water diving places great emphasis on having immediate/swift access to the surface as a contingency for emergencies whilst diving.
6) When doing exams/quizzes, answer the question you are asked. If the question asks for a maximum ascent speed recommended by that agency, then supply that. If you supply a different answer, you will get the question wrong...and fail.
For a really good insight into ascent speeds, stops, dive tables and computers... do read Mark Powell's 'Deco for Divers'. Your boyfriend, as a prospective technical diver, would love reading that book too...
Article: Best Ascent Speed for Scuba Diving
victorzamora
Contributor
Andy, that's a great post per usual. One thing you mentioned that I, and a couple others, had forgotten to mention is the difference between "maximum" and "optimal" ascent rates.
There's also a "minimum" ascent rate, and that's what my post was concerning. It IS worth noting, however, that many places still teach 60fpm as max and 30fpm as optimal. Many consider 20fpm to be minimum, until you get to 30ft or so....and then some are suggesting 10fpm above that.
There's also a "minimum" ascent rate, and that's what my post was concerning. It IS worth noting, however, that many places still teach 60fpm as max and 30fpm as optimal. Many consider 20fpm to be minimum, until you get to 30ft or so....and then some are suggesting 10fpm above that.
As a 45 year-old male with lots of relationship experience with women, trust me, the boyfriend is always right. Don't make the same mistake as my ex-girlfriends. 
An interesting tidbit about the history of ascent rates: When Jacques Cousteau and Emile Gagnan patented the Aqualung in 1945 (patent CG45 for "Cousteau" + "Gagnan" and "1945") and the unit was adopted by the US Navy the ascent rate the new SCUBA divers wanted was 120 feet per minute while the hard hat tenders wanted to hoist a diver at 30 feet per minute. The Navy couldn't have two different ascent rates and decided to just split the difference at 60 feet per minute for their tables.
After you are certified, practice your controlled ascent rate and practice holding your decompression stops. Also practice sharing air while ascending and while performing safety stops. Doing it a couple times in class doesn't mean you'll be able to do it well without practice and with a different buddy than you had in class.
An interesting tidbit about the history of ascent rates: When Jacques Cousteau and Emile Gagnan patented the Aqualung in 1945 (patent CG45 for "Cousteau" + "Gagnan" and "1945") and the unit was adopted by the US Navy the ascent rate the new SCUBA divers wanted was 120 feet per minute while the hard hat tenders wanted to hoist a diver at 30 feet per minute. The Navy couldn't have two different ascent rates and decided to just split the difference at 60 feet per minute for their tables.
After you are certified, practice your controlled ascent rate and practice holding your decompression stops. Also practice sharing air while ascending and while performing safety stops. Doing it a couple times in class doesn't mean you'll be able to do it well without practice and with a different buddy than you had in class.
You're getting good advice... one thing I would add: 30 f/min NO SLOWER until you get to your safety stop at 10 or 15 feet and from there to the surface 10 f/min... generally speaking that's best practice for sport divers...
Good luck, have fun, enjoy!
Good luck, have fun, enjoy!
razorbackdiver
Contributor
During your course your instructor will not only be responsible for teaching you to dive but your safety also. Even if you have a great instructor you will probably still have a lot to learn after your class. Your boyfriends plastic does not mean much. You should ask other to evaluate not only your diving but also his to see if he truly knows what he is doing. A good mentor is worth their weight in gold. A bad mentor isn't worth a wooden nickel. After your class your safety will fall somewhat on him until you have more experience. His safety will fall somewhat on you by not putting yourself in a situation where where has to ascend to fast to catch you if you get to buoyant. 30ft/min gives you and him a greater saftey factor.
The boyfreind.
The boyfreind.
Last edited:
Similar threads
