Recreational divers often desire to do more than 1 dive in a day. This is understandable since many recreational divers visit locations far away from home and want to get as many dives in as they safely can.
The number of dives you can do per day depends on the depth and length of each dive. For recreational divers, a typical limit is 4-5 dives per day as long as you follow dive tables or use a computer to track.
For shallower depths, you will need to refer to dive tables to be able to determine how many dives you can safely do in a day and how long those dives can last. Below you will find a straightforward explanation of what dive tables are and how to use them.
Before the dive computer days, my maximum dives in one day was 5 following dive tables. Two tanks in the morning, two shallower ones in the afternoon and a late night dive at the Sugar Wreck in 20 feet of water off Freeport, Bahamas. A well-planned day usually starts with the deepest dive first with shallower dives later in the day to prevent nitrogen build up in the bloodstream.
Use a dive computer to track
Please read the whole post for greater understanding of why dive frequency, time and depth have limits. If you simply want to maximize your dives per day the safest way, buy a dive computer. They come in many different sizes, styles and price ranges.
Set Up A Dive Plan Before You Go
Regardless of how many times you plan on scuba diving throughout a single day, you are encouraged to set up a dive plan for each and every dive. A dive plan is a checklist for the dive that will help you keep inventory of all the supplies you will need to have on hand as well as prod you to take account of all the safety hazards that you may encounter.
A complete dive plan includes the following:
- Date of the proposed dives
- The stated purpose of the dive
- (i.e: recreational or educational or as specific as you would like)
- Decompression status and repetitive dive plans
- A list of equipment and boats to be employed
- Any anticipated hazardous conditions
- (i.e: boat traffic overhead, low visibility, debris that divers may get hung up on)
- Name of the lead diver and all buddy divers
- Include information on how experienced the divers are, including any accreditations
- Emergency plan including emergency contacts
- Procedures for a diving accident
It is recommended that you make at least two copies of the completed dive plan. One dive plan will be submitted to a trusted individual on-shore. The other copy of the dive plan should be put in a waterproof holder and placed within an easily-accessible storage area of the vessel that you plan on diving from.
How Many Scuba Dives Can You Do In A Day?
Technically there is no specified limit on the number of times that you can dive in one day. The number of times that you can safely scuba dive in one day is dependent on how much nitrogen your body will take in. Nitrogen is harmful to divers. Decompression sickness, colloquially referred to as “the bends”, can even be fatal in some cases.
The reason that decompression sickness occurs during diving (source)
- If you are scuba diving with compressed air, then your body will taking in both extra oxygen and extra nitrogen
- The body uses the oxygen
- The nitrogen portion is dissolved in the blood, remaining there for the duration of the dive
- When the diver ascends rapidly at the end of the dive, bubbles are formed in the blood
- The nitrogen gas bubbles also accumulate in the muscles, making this a painful sickness
Your exposure to Nitrogen while scuba diving will depend on:
- Maximum depth reached
- Length of time spent at said maximum depth
- How long you have waited between dives
- Number of previous dives in a day
- Number of divers performed in previous days
Depth and Duration Of The Dive
The depth and duration of the dive have a limited impact on the onset of decompression sickness, (source.) That being said, there is far greater risk of neurological decompression sickness if the dive is deeper than 131 feet. As you will learn in the section below, it becomes much harder to do repetitive dives the deeper you decide to go.
Control Your Ascent
The most significant factor when it comes to To decompression sickness is the speed of ascent towards the surface. To prevent the formation of decompression bubbles, I’ve written that divers need to stage their ascent to the surface. The consequence of this is that you may not be able to do as many dives in one day unless you take great care during the ascent. It is clearly worthwhile to take the necessary precautions to prevent decompression sickness.
More conservative diving techniques include:
- Not diving too deep
- Staying for shorter periods underwater
Scientific divers, who have to frequently scuba dive for research purposes, have found that the ascent should be controlled in the following manner:
- A 3-5 minute stop should be made for every 5 m (16 ft)
- It has also been found that making repetitive dives over multiple days, may result in a greater risk of getting decompression sickness.
How Long Should You Wait Between Dives?
You can determine just how long you should wait between dives by using a dive compression table. These tables have been put together after extensive research on the medical impact of repetitive diving.
NAUI (National Association of Underwater Instructors) has produced its own dive tables based on those used by the U.S Navy. They have adjusted accordingly for recreational diving purposes. These tables have simplified the process by using letter groups to signify how much residual nitrogen is in your system. The letters range from A to L, with A representing the smallest amount of residual nitrogen that you could have in your system
NAUI has produced 3 different tables for repetitive divers:
- End of Dive Letter Group
- This table shows how much nitrogen you can expect to be in your system at a given depth and time spent diving
- The chart also shows many minutes you should spend at each 15 foot stopping interval during your ascent, provided that you have spent an excessive amount of time at the given depth
- Surface Interval Time (SIT)
- This table shows the amount of time you spend resting between dives
- You will notice that should take at least 10 minutes of rest between dives
- Times are shown in a range. You may be assigned to a different letter group, depending upon how much of a rest you take
- Residual Time Table
- This table shows the maximum amount of time you can spend at a given depth, depending upon how much of a rest you took
- If you take short rests between dives then the amount of time you are able to spend on the second dive will be dramatically reduced
- The chart shows that you cannot safely do more than 1 dive a day at 100 feet or deeper
The NAUI tables are designed to be a flowchart. You are encouraged to do at least a few hypothetical readings before you hit the water. You may be surprised at how little time you can spend on repeating dives, particularly if you are going 60 feet or deeper. Carry a laminated dive table with you on your diving trips.
If you are an avid scuba diver, you are likely to find that it is much more convenient to use a watch with a built-in dive computer. Dive watches are particularly useful for repetitive divers. As you can see above, it can be easy to lose count of your residual nitrogen level if you are only relying on a dive table.
The Final Word
Dive tables will ultimately determine the number of dives you can safely do in a day. Nitrogen is the biggest limiting factor for scuba diving. When you are on land, your body can release accumulating nitrogen. However, the pressure of water prohibits you from shedding potentially harmful nitrogen when you are diving underwater. It is this factor above all that limits the safe number of dives you can do in a day.
Of course, you must also listen to your body, stay hydrated and take in enough calories to avoid fatigue, and rest between dives. Don’t do vigorous exercise on days that you dive, as we’ve previously discussed. Follow these tips, and you can maximize your bottom time and your underwater exploration.
