Depths limits for Scuba qualifications and the reasons for them
Open Water 60 ft. Advanced Open Water 100 ft. Maximum recreational depth 130 ft.
These limits progressively become deeper as you develop your skill set and take further training courses.
Why the 40 ft Limit
This is the depth for absolute beginners such as Discover Scuba Divers and Open Water students on dives 1 and 2.
At this depth the NDL limit is over 2 hours, a new diver will use a tank of air in about 40 minutes at this depth.
This removes the need to calculate NDL, one less thing for a beginner to consider.
Also light level and visibility should be good.
Particularly important when training new divers, problems are more easily handled when shallow.
Background to the 60 ft limit for new divers.
As a new diver you learned a certain skill set to enable you to dive safely. Your certification allows a maximum depth of 60 ft, there are actually good reasons for this:
The NDL for 60 ft on air is 55 minutes (Padi tables), most inexperienced divers won’t get near this limit due to air consumption.
Safety stops are just that, safety stops, a new diver who has not been deeper than 60 ft and kept within the NDL, misses a safety stop due to poor buoyancy control, well probably nothing bad will happen, not good practice though.
Nitrogen Narcosis is virtually unknown at 60 ft.
New divers learn to be back on the surface with 500 psi, this means they start their ascent with probably 700 psi, if at that point their buddy has a gas failure, there will be enough gas to get 2 divers safely to the surface, no “rock bottom” calculations needed.
You don’t know what you don’t know, there are many things to consider when diving deeper, too many to cover in detail on an Open Water Course that lasts 3 days.
Why becoming an Advanced Diver allows you to go deeper.
An Advanced Open Water Diver takes further study and develops a new skill set for the deeper dives. This develops knowledge and removes a lot of the “don’t know” dangers.
This skill set includes:
A more thorough understanding of the causes of and how to prevent DCS.
The importance of dive profiles.
An understanding and maybe even experience of Nitrogen Narcosis.
Gas planning skills, gas management skills and the concept of “ I must always have enough air in my tank to get me and my dive buddy to the surface safely with safety stops” (rock bottom gas).
Improved and detailed dive management skills, use of a dive computer, making and following a dive plan, carrying correct safety equipment for the dive.
Improved navigation skills.
And a Deep Diver can go to maximum recreational depth.
Going below 100 ft to the maximum recreational depth of 130 ft brings new risks and requires more detailed dive management, that is why further training such as the Padi Deep Diver course is needed.
Personally I am a trained technical diver, (teaching recreational scuba is my job, technical diving is my hobby), this training has taught me to plan a dive below 100 ft in the same way I plan a technical dive with regard to gas management.
By this I mean that I never go that deep without a proper gas management plan and equally importantly a second completely independent air supply.
The additional air supply allows me complete self sufficiency with regard to air. (Actually I introduce the concept of a pony bottle for the deep dive of AOW when I am teaching).
There are no “small problems” below 100 ft, every issue has the potential of very quickly becoming a major problem, quality training helps us to ensure that these small problems don’t grow to become major disasters.
In Summary
There are no Scuba Police out there, we are all adults, it is up to you and your dive buddy to plan your dive and dive your plan.
Depth is not “just a number”, make sure you are totally 100% comfortable with your diving skills before venturing beyond 60 ft.
Be aware the risk increases exponentially with depth and try to appreciate that “ You don’t know what you don’t know”.
Be aware that your air consumption increases.
Watch your NDL limit.
Stay close to your Buddy.
There is a lot of personal satisfaction in diving at a deeper depth to see that special “something”, just extend your depth limit slowly, stay within your comfort level, don’t take risks and if going deeper is your thing, take further training to really learn the required skill set.
Ultimately the decision on how deep to go is yours and yours alone.
Two departing thoughts:
1. Medical Insurance for Scuba Diving.
Some insurance companies will only cover you to the depth to which you are certified, check this out particularly if your diving insurance is part of a travel plan, rather than specialist dive insurance.
2. Dive accidents.
According to statistics most dive accidents occur with divers who have limited experience:
The DAN fatalities workshop of 2011 found that there is a real problem that divers do not follow the procedures they have been trained in, and dive significantly beyond their training experience and fitness levels, and that this the basic cause of most accidents. In litigation involving diving accident, the legal panel reported that 85% to 90% of the cases were attributable to diver error. This is consistent with several scientific studies. Medical issues are a significant part of the problem, and certified divers are responsible for assessing their own fitness and ability to do any particular dive. Experience was also cited as a significant factor, with occasional divers at higher risk than regular divers, and the majority of fatalities had only entry level or slightly higher qualification.
https://en.wikipedia.org/wiki/Scuba_diving_fatalities
