TDI Advanced Nitrox & TDI Decompression Procedures

MIMIMUM - Gear Requirements:

Bernie Chowdhury’s Gear Recommendations

NOTE:  if you are unsure about whether or not your gear is adequate for the courses, or for your diving goals, please ask.  I’ll be happy to discuss it with you before you commit to the course.  During the class, we’ll be going over equipment, ways of rigging, etc.  One of the things you’ll learn is that gear configuration is something that evolves for each diver depending on their needs, their goals, and the environment(s) in which they dive.

If you do not have all of the required gear, do not panic.  You may be able to use some of my extra gear for the course(s).  Again, we need to establish this before the course so that we’re prepared.

Please let me know what your diving goals – both immediate and perhaps “wish list/future” stuff.  Do you want to learn these skills for possible use in, say, the 130 foot range to make your diving safer?  Perhaps slightly longer dives?  Or do you wish to ultimately be able to dive much deeper on some specific sites?  Either way, I’ll be able to help you prepare and have much more enjoyable dives.

If you wish, we can make arrangements for me to dive with you on your “wish list” site(s).  In some cases, we might be able to do this as part of this course.  In other cases, we will want to (or may be required to) complete training first and then do the “wish dive(s)” at another time.


TDI Advanced Nitrox (minimum gear requirements)

•    Alternative second stage octopus attached to a primary regulator OR a redundant scuba unit (13 cu ft / 370 liter minimum).
•    Submersible Pressure Gauge.
•    Depth gauge and automatic bottom timer AND/OR dive computer.
•    Buoyancy Compensator with power inflator.
•    Exposure suit adequate for the open water environment.
•    Cylinder and Regulator properly labeled and cleaned as required for Enriched Air Nitrox (EAN) mixtures.
•    Access to oxygen analyzer (You may use my analyzer during the course.)


TDI Decompression Procedures (minimum gear requirements)

•    Primary scuba cylinder(s).  Cylinder volume appropriate for planned dive and student gas consumption.
•    Decompression Mix Cylinder(s)
•    Cylinder volume appropriate for the planned dive and student gas consumption with submersible pressure gauge.
•    Cylinders labeled in accordance with TDI Standards. [Percentage of oxygen, Maximum Operating Depth (MOD) ]
•    Depth gauge and automatic bottom timer AND/OR dive computer.
•    Regulator(s)
•    Primary and alternate 2nd stage required on all primary cylinders.
•    Submersible pressure gauges are required on all primary cylinders.
•    Buoyancy Compensator(s) adequate for equipment configuration.
•    Jon-line and other rigging lines as dictated by site conditions.
•    Ascent Reel with Life Bag/Surface Marker Buoy.
•    Adequate for maximum planned depth.  [The line on the reel has to be long enough to reach the surface.]
•    Minimum of twenty-five (25) lb / eleven (11) kg lift bag.
•    Oxygen analyzer (may be supplied by the instructor).
•    Underwater Slate.

Bernie Chowdhury’s recommendations:

In general, when you’re doing decompression diving, you are entering an “overhead” environment: you cannot make a direct ascent to the surface without serious risk of Decompression Illness (DCI), otherwise known as “the bends” or “Decompression Sickness” (DCS).

Your scuba equipment is your life-support apparatus.

Don’t skimp when buying gear.

Get the best.

Your life depends on it.

If you need one of something, you really need at least two; examples: regulators, lights, cylinders/tanks, depth and bottom timers, computers, etc.

PRIMARY TANKS:

If you’re going to get into decompression diving, or you’re doing any diving in the US northeast or comparable areas, you should have at least two tanks.  Those can be a single primary and a pony, or double tanks, worn either as independent singles or doubled up in a dual-valve manifold configuration.  There are a few different ways to do this, which we’ll cover in class.  If you have independent singles, you must have TWO submersible pressure gauges (SPG): one SPG on each tank.  

You should have a BC with adequate lift for your full tanks plus your own weight with all the gear you wear.  This will help you to be self-reliant and self-sufficient.  If you are unsure about what size tanks to get, talk to me.


STAGE or DECOMPRESSION TANKS:

While a 13 cu ft / 370 liter cylinder is the smallest required of TDI, I recommend a larger tank.  Keep in mind that you may need a larger tank anyway, based on the dives planned, e.g. depths, time, etc, as well as your personal gas consumption level.  Again, if you’re unsure, talk to me.


Buoyancy Compensator (BC):

You should have a BC with adequate lift for your full tanks plus your own weight with all the gear you wear.  This will help you to self-reliant and self-sufficient.  If you are unsure about what size tanks to get, talk to me.

The most common technical diving configuration today is a “Wings” style BC with backplate.  Softpack BC’s are also used, however, these tend to roll the diver too much for use in overhead environments such as wrecks or caves.  Remember: decompression diving is a “virtual” overhead environment.  If you plan on diving wrecks and/or caves in the future (and both of these require additional training and equipment) you should get the wings style BC with backplate.

REGULATORS:

Get the best regulators you can afford.

You should have at least one top-rated primary, and preferably two top-rated primary regulators.



LIGHTS:

At least one primary light of high intensity and with adequate burn time to last your entire planned dive.  At least one back-up light.  (Overhead environments such as caves and wrecks require you to have a primary plus TWO back-up lights.)

DEPTH GUAGE & BOTTOM TIMER / DIVE COMPUTER:

You should have and wear two of these, in case one fails.  While you will be taught about contingency plans and should dive with those written on your slate(s), having two timing devices is essential to making sure you can follow a primary or contingency plan.

REEL:

Used as a guideline and also as an “upline” or emergency ascent line.  Have at least one of these, but preferably two.  Make sure the line is thick enough for use in the environment we’ll be diving and also that it has enough line on it for the depths you’ll be diving.

LIFT BAG:

While a 25 lb bag is the minimum, for diving in cold water, I recommend a 50 lb bag as the minimum, with a 100 lb bag recommended.

THERMAL PROTECTION:

You’ll be far more comfortable wearing a dry suit when doing decompression diving in cold water, and even in “warm” water when doing long exposures (anything over one hour).  If you have not been using a dry suit in your diving we need to work on those skills first before you progress to decompression diving in cold water.

FINS:

I recommend solid fins, such as the Jet Fin, to propel you and all of the gear through the water, especially against the current.  Split fins?  I have tried them and am very dubious that they will give you the propulsion you need when wearing tech gear. Either way, it's recommended that you use stainless steel spring straps on your fins.

SLATE:

I recommend the multi-layer forearm slate.  Both OMS and Dive-Rite produce these.  (Other companies may as well.)


OTHER:

UNDERWATER GEAR BAG, AKA “THE MAGIC BAG”:

Having an underwater gear bag made of heavy canvas allows you to put much of your accessory gear -- such as reel(s), liftbag(s), jonline, extra mask, etc. -- in one place and carry it all easily, with quick access.  I will show you how to rig the bag, and how it is commonly worn.  I’ll also show you how to make modifications to streamline the underwater bag.

Alternatively, some people like to use a couple of large equipment pockets that they can wear on their Wings style BC hip webbing.  I know that OMS produces these pockets.  Other companies may as well.

THERMAL PROTECTION:
 You’ll be far more comfortable wearing a dry suit when doing decompression diving in cold water.  If you have not been using a dry suit in your diving we need to work on those skills first before you progress to decompression diving in cold water.

FINS:
  I recommend solid fins, such as the Jet Fin, to propel you and all of the gear through the water, especially against the current.  Split fins?  I have tried them and am very dubious that they will give you the propulsion you need when wearing tech gear, though some divers swear by them.  The split fins also present a potential line trap at the place furthest away from your arms, e.g. it will be a challenge for you to remove netting, monofilament line, or kelp that is tangled in the “split” portion of your fins.  Regardless of split fin or solid fins, it's recommended that you use stainless steel spring straps on your fins.  Rubber or silicon straps can break, with potentially dire consequences.

AGAIN:
Please ask if you have any questions, especially about the gear that you currently own and whether or not that can be used for the courses.

I look forward to diving with you.

All the best,

Bernie Chowdhury, CHT
TDI #12347
(DAN #12737;  NAUI #10304;  PADI #37889)