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Dive safety and security Through Education

Since the beginning of scuba, professionals have led the means in every significant development in the sport. An ext than any kind of other team of expert educators, leader have identified the patterns in diving and inspire the future.

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Dive Table Overview


Please note that as result of differing display resolutions and color depths, no everyone will see the data same clearly. naturally recommends the each diver own a personal copy that the tables.

The Dive Tables use a Letter team designation come express the lot of residual nitrogen in her body. The letters variety in sequence from A to L. The letter A represents a little amount the nitrogen and the lot of nitrogen rises as the letters development towards L. When you dive, a Letter team from the tables designates the amount of nitrogen friend have absorbed during the dive. Together you invest time on the surface in between dives, you space assigned come “lower” Letter groups as girlfriend offgas nitrogen.

When you start a dive again to a given depth, your Letter team at that time determines the moment representing the residual nitrogen in her body. The tables display you just how to subtract this time from the normal dive time limits, which outcomes in a much shorter time border for your repeated dive. Girlfriend must add your residual nitrogen time to the moment you actually spent diving to identify your total nitrogen time at the end of the dive. You use the full time to identify a brand-new end-of-dive Letter Group. The dive time calculator is based on the dive tables, but it eliminates the calculations forced to determine Letter groups when friend make much more than one dive. The dive time calculator additionally reduces the errors that are regularly made as soon as reading dive tables. The is straightforward to learn exactly how to usage a dive time calculator, yet you must do this just after you are acquainted with the steps for plan dive time boundaries using the dive tables. A dive time calculator might not always be available, but dive tables usually room (figure 5-4).

A selection of dive tables, dive time calculators, and dive computers exist. The info they provide varies and some are an ext conservative 보다 others. Numbers and Letter teams are not always interchangeable between tables. Constantly use the form of table, calculator, or computer system with which you space familiar. If her dive friend is making use of a different type, you must agree to use the most conservative dive to plan information.

Dive Table Organization

The Dive Tables space composed of 3 tables:

Table 1 – End-Of-Dive Letter GroupTable 2 – surface Interval Time (SIT) TableTable 3 – repeated Dive Timetable

The Dive Tables are based on the us Navy Decompression Tables and also have been designed particularly for entertain diving (figure 5-6). The tables are designed to flow from one come the various other in a constant loop (figure 5-7).

When you are using the tables, be certain to usage a leader or a straight-edged object to read the numbers across and job-related your means from table come table. If you try using a finger to map your path through the tables, you might slide into one more row and also read the table incorrectly, particularly if you room on a rocking boat.


Dive Table Terms

Different dive tables and dive computers might use terms various from the ones offered in the Dive Tables (figure 5-5). Also, the very same term can have a various meaning.

The following terms use to the Dive Tables:

Dive ScheduleThis is an abbreviated statement giving the depth and also time that the dive. It is expressed as depth/time (for example, 21 meters/40 minutes or 70 feet/40 minutes). The is also called a dive profile, especially when it is one dive in a succession of dives.Maximum Dive Time (MDT)This is the time you have the right to spend in ~ a given depth without having to perform a compelled decompression stop throughout ascent. This time is additionally known together the preferably Allowable Dive Time or no-decompression ddmit.Decompression StopThis is a point in a dive wherein you stop at a specified depth because that a stated time during ascent to permit nitrogen offgassing before continuing your climb or surfacing.Precautionary Decompression StopThis is a prevent at 5 meters (15 feet) for 3 minutes together a security precaution as soon as you have not exceeded the preferably Dive Time. You must perform together a stop at the end of every dive. It is likewise known as a safety and security Stop.Required Decompression StopThis is the amount of time mentioned by the Dive Tables, the you have to spend at five meters (15 feet) whenever friend exceed the preferably Dive Time. Other tables specify extr stop depth for depth or longer dives.Actual Dive Time (ADT)This is the elapsed time indigenous the moment you begin your lower from the surface ar until the moment you return to the surface. Time spent at her Safety avoid does not have to be consisted of in the actual Dive Time once determining your Letter Group.Residual NitrogenThis is the overfill nitrogen continuing to be in your body from any dive or dives made before you have totally offgassed.Letter team DesignationThis letter symbol identify the quantity of residual nitrogen you have in her system. The closer the letter is to the start of the alphabet, the much less residual nitrogen you have in her body.Surface expression Time (SIT)This is the time invested on the surface between dives. During this time, her body is eddminating overfill nitrogen. Her Letter group will change and relocate closer come the start of the alphabet, depending on how long you are on the surface.Repetitive DiveThis is any type of dive that you make prior to you have totally offgassed from any type of previous dive or dives.Residual Nitrogen Time (RNT)This is the lot of time friend must consider as currently having been invested at a provided depth because that a planned recurring dive. This time is based upon the residual nitrogen continuing to be in her body native a vault dive or dives.Adjusted best Dive Time (AMDT)This is the preferably Dive Time minus the Residual Nitrogen Time because that a repeated dive to a given depth.Total Nitrogen Time (TNT)This is the sum of your Residual Nitrogen Time and your really Dive Time complying with a recurring dive. You use this full to achieve your brand-new Letter team at the finish of the dive.

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Dive Table Rules

You must recognize the following Dive Table rule completely. Similar rules will apply to any brand-new set of dive tables or dive computer system that you might use come calculate your dive times.

Ascend no quicker than 9 meter (30 feet) every minute. This is 0.3 meters (1 foot) every two seconds. You need a timing an equipment and a depth gauge (or a dive computer) to measure your price of ascent. This rate will seem fairly slow come you.Use the specific or the next higher number listed in the table for her depth. If girlfriend exceed a number in the table, usage the next higher number. The depth in the table range from 12 meters (40 feet) come 40 meter (130 feet) and also increase in increments that 3 meter (10 feet). Because that example, you round a dive come 13 meter (43 feet) up to a 15 meter (50 foot) dive.Use the exact or the next better number provided in the table for her time. If you exceed a number in the table, usage the next better number. The times variety from 5 minute to 130 minutes. Because that example, you ring a dive to 15 meters (50 feet) because that 41 minutes up to 50 minutes.Use the deepest depth girlfriend reached throughout your dive to identify the dive schedule for her dive. For example, if you carry out a dive to 18 meter (60 feet), however spend most of the time at 12 meter (40 feet), friend must think about the dive to be an 18 meter (60 foot) dive.Always make your deepest dive very first when do a collection of dives. Setup each of your repeated dives come a shallower depth 보다 your vault dive. This might enable you come offgas nitrogen on increasingly shallower dives and also prevents girlfriend from carrying significantly larger quantity of residual nitrogen on deeper recurring dives.Consider any dive shallower than 12 meters (40 feet) to it is in a 12-meter (40-foot) dive once planning her dives.Surface term Time (SIT) should be at least 10 minutes in between dives. If her SIT is much less than 10 minutes, friend must think about your second dive together a continuation of the first dive. proposal a SIT that at the very least one hour in between dives.Use the next better dive time if her dive is particularly cold or strenuous. Because that example, if you execute a dive to 18 meter (60 feet) because that 22 minutes, the 22 minutes rounds to 25 minutes. However, if you come to be chilled throughout the dive, round the moment again come 30 minutes.Avoid dives that take you best to the no-decompression border for any kind of given depth and time combination. If friend accidentally overstay your bottom time or usage an incorrect climb rate on such a dive, you could be in a forced decompression situation or experience DCS. Always allow yourself enough time to make a slow, comfortable ascent with plenty of air.