This question may seem deceivingly straightforward, but the answer is surprisingly far more complex. Scuba diving is undertaken for various reasons. The same rules will apply whether a person is diving commercially or recreationally. There may, however, be differences where certain factors need to be taken into consideration.
There is no universally set time for a scuba dive. The factors that affect dive time are consumption of air, absorption of nitrogen, depth, and tank volume. Other less stable factors will further influence the outcome. An “average” first-time safe dive (30-60 ft.) will last 45-60 minutes.
Diving times will vary for many reasons. Before you begin your exploration of the deep blue, it is imperative for you to understand the mechanics, biology, and science that goes into scuba diving. Once you have a better grasp on how you can lengthen your time underwater (if you wish), you can then ensure that your dive is rewarding, enjoyable, and, most importantly, safe.
Factors Affecting Dive Time
As mentioned, a lot of things are taken into consideration prior to a dive. Some of these are more constant and scientific in nature, whereas other factors are prone to fluctuation, change, and unpredictability. These factors could see your dive time being cut short at a moment’s notice.
Consumption Of Air And Its Effect On Your Dive Time
The volume of the air in a tank won’t necessarily last the same amount of time for different divers. The rate at which the air is being consumed by the diver will directly determine the length of the dive. While you may think that “air consumption” is on par with your natural breathing pattern, external and personal factors affect your consumption rate.
External factors that affect the rate of air consumption include:
- The weight of your equipment
- The size of your equipment
- The shape of your equipment (streamlined is better)
- Adverse currents (may lead to more movement and exertion from the diver)
Personal factors include:
- Lung capacity (your size, health, age, and habits may be contributing factors)
- The speed at which you move underwater
- Your natural breathing pattern
- Your state of mind (stress will affect your heart rate and breathing)
Tank Volume And Its Influence On Your Dive Time
It goes without saying that the volume of your tank is quite a pertinent factor when considering your potential time underwater. Obviously, a larger tank equates to a larger supply of air and thus a potentially longer dive. For recreational diving, the average tank size that is most commonly used is a 12L aluminum tank.
This tank holds 80 cubic feet or 3000psi (pounds per square inch) of compressed air. As mentioned earlier, how long the air in any tank lasts depends on the consumption. It is key to note that just because there is still air remaining in your tank (even if your time is almost up), you should not extend your time underwater until the tank level is low.
It is advised (strongly) that recreational divers resurface with no less than 500psi left in their tanks.
Depth and nitrogen absorption will further influence tank volume and air consumption rate.
The Effects That Depth And Nitrogen Absorption Have On Your Dive Time
When considering recreational diving, the average limit is 130 ft. (as set by the US Navy in the 1950s). This depth limitation is geared towards divers with more experience and expertise. First-time divers will partake in a shallow dive which will not exceed 39 ft. in depth or 50 minutes (all things considered) in time. Anything above 60 ft. is classified as a deep dive.
Great care needs to be taken with deeper dives. The deeper you dive, the more the pressure around you increases. The change in the ambient pressure will affect the air that you are consuming from within your tank. An air tank contains compressed air, which is made up of 21% oxygen and 79% nitrogen.
While the air is contained within the tank, the change in pressure will not affect it. When this air leaves the tank and travels through the hoses and into the diver’s mouth, the surrounding water pressure even further compresses this air.
So what does the pressure increase actually mean for the diver? Consider the contents of your scuba tank. Both the oxygen and nitrogen will be absorbed by the organs in the body due to the pressure increase. Oxygen does not pose a risk due to the fact that it is used by your organs for metabolic purposes.
Your organs have no use for nitrogen, and it will end up being stored in your tissues and blood. The absorption of nitrogen does, however, pose more of a risk. If the nitrogen does not have sufficient time to clear from your blood, it will separate and form bubbles, which will lead to decompression sickness (aka the bends).
Diving at deeper depths means that the nitrogen is more easily absorbed. That is why deeper dives have a shorter time frame. If you would prefer a longer dive, then consider shallow or drift diving.
The diving community has a common saying: “Plan your dive and dive your plan.” When planning your dive, it is in your best interest to consult the dive table developed by the US Navy. This chart will clarify your depth and time restraints and ensure that you do not put yourself or others at risk.
Personal And Inconsistent Factors That Will Affect Dive Time
The factors mentioned above are rather technical and almost constant in nature. These can be controlled, measured, and managed to ensure that your dive is safe and fruitful. Other things will further impact the amount of time you spend underwater, and some of these things may be beyond your control.
How Your Health Can Affect Your Dive
It is not an absolute requirement to be a fitness fanatic or a gym bunny to enjoy scuba diving. But having medical conditions or health problems may affect your overall diving experience. The health preferences for any diving endeavor are in place to guarantee the safety of the diver.
General overall healthy body weight and fitness levels are not mandatory, but the health and safety risks are much greater for those that are overweight or lack physical fitness. If you begin to take strain underwater, your air consumption may increase, or you may find yourself returning to the surface sooner than you had hoped due to discomfort or tiredness.
Diving is not recommended if you are or suffer from any of the things listed below:
- Obese or overweight
- Have known heart conditions
- Have known lung conditions or poor lung capacity
- Boarding a plane less than 48 hours after your dive
- Insufficient fitness levels
- Under the influence of any drugs or alcohol (chronic and prescription medication should be brought to your dive master’s attention)
- Untreated or unmanaged hypertension
- Chronic fatigue
- Drastic health changes due to aging
- Severe sinus conditions or inner ear issues
It is highly recommended that you get certified or undergo training before you embark on a diving expedition. The certification will address any health issues you may be unaware of or unsure of.
How Your Experience Or Lack Thereof Can Affect Your Dive Time
If you are a first-time diver, then some trial and error can be expected. Like so many things in life, when it comes to scuba diving, “practice makes perfect .”Divers who have clocked more hours underwater or who have done extensive research will hypothetically have a longer dive time.
They have a practical understanding of underwater conditions, equipment, and air consumption management. Do not rush yourself to be at the same level too soon.
There is no shame in ending your dive sooner than others. With more training, you will learn to control your movements and adapt to the environment in a way that allows you to make the most out of your time, air supply, and depth. Just remember that your safety is the number one priority.
The Effect Of Water And Weather Conditions On Your Dive Time
Just because you are below the surface does not mean that your dive or the ocean won’t be affected by environmental occurrences such as rain, storms, and rough waves. These factors may very well lead to your dive either being ended prematurely or, in dire cases, completely called off in advance.
Below are several factors courtesy of Mother Nature that may alter the length of your dive:
- Water Temperature
While you may be diving in water that is ideal for swimming, the same body of water will feel much colder when you are scuba diving. The suits that are worn on diving excursions have been designed for this very reason.
The human body loses heat significantly faster to water than it does to the air. If your wetsuit does not provide adequate thermal protection, you may find yourself resurfacing a lot sooner than expected.
Poor visibility can result from an array of environmental factors, be it currents, weather, temperature gradients, or salinity gradients. If visibility is poor, it makes the dive not only unsafe but also rather pointless, which in turn will cut your time underwater short.
- Water Movement
Surge and strong currents will not make your dive impossible. The conditions may be less than desirable, but you will find that more movement will be required on your part, which will result in a faster depletion of your air supply as well as your energy levels.
The People In Charge And Their Say On The Time You Spend Scuba Diving
Also, take into consideration the discretion of the dive master and the time constraints of the boat operator. Your time and depth may very well be prescribed to you prior to your dive. The operator of the boat more than likely has a schedule that needs to be adhered to and other dive sites that need to be reached.
You should always listen to and follow the instructions of the dive master. They will use their expertise in their field as well as their discretion to determine whether or not a dive is no longer safe. And even within these time limits, you may find that the dive master has called you back to the surface sooner than you thought.
How Long Can You Scuba Dive For In Terms Of Age And Years?
Scuba diving has absolutely no age limit as long as you are in good health. William Lambert holds the current record for the world’s oldest male diver at 100 years (and two days) old. Like with any physical activity after a certain age, you should consult your doctor, and certification needs to be completed.
Children as young as the age of eight can begin scuba dive training; however, they do not exceed depths of 6ft. Generally, children between the ages of 10-12 can be certified for recreational diving. Age limitations may vary depending on the agency through which the certification is done. As long as the child in question is physically, mentally, and emotionally capable (along with the parent’s consent), they shouldn’t have a problem getting certified.
If you are aiming for a longer dive time, stick to shallower depths and follow the tips that ensure that your air supply is not being used up rapidly and unnecessarily. The point of a scuba dive is to have an immersive and visceral experience. A longer dive does not necessarily mean that you will see more. Be sure to select diving points that are suited to your preferences.
While a lot of scuba diving is very technical, recreational diving is meant to be enjoyed. A lot of preparation and perhaps training or practice may be required, but that is a small price to pay where your safety is concerned, not to mention the incredible view and experience. And remember to “Dive your plan and plan your dive.”