Blog

DDS Diver Grace doing a CCR Trimix Dive in Bon Echo Park

When Should You Get a Rebreather

When Should You Get a Rebreather
by
Matthew Mandziuk

Lately people have been asking us about rebreathers and when they should consider going that direction…So I figured “When Should You Get a Rebreather” would be a fun topic to write about.

Rebreathers are a simple concept.  A rebreather is in essence like breathing from a “sealed bag” is filled with a breathable gas mixture.  As you breath each breath, you deplete the oxygen in the “bag” through the process of metabolizing the oxygen and putting back in the lung exhaled breath with a lesser partial pressure of oxygen until the “sealed bag” or “lung” would go hypoxic (think of breathing in and out of a paper bag as a concept), meaning not enough oxygen is in the gas you’re breathing to sustain life.

You would have to replace the depleted oxygen with more oxygen, but in addition to this, you’ll also have make sure that carbon dioxide is also being absorbed/eliminated from your rebreathed gas, so we need to “scrub” the CO2 out with a CO2 “scrubber”….Sound simple?  It is overall.

Below we will discuss who should dive a rebreather, the different basic designs and features, key elements, dive planning and more.

There are 2 types of rebreather concepts.  Semi-Closed and Fully Closed.

fathom rebreather rigged up as the tech version with faber LP50 tanks, Lola valves, atomic regulators, custom black camo halcyon evolve jj wing with maroon center, spg on left hip with diluent injection through the left hip d-ring
Fathom MK2.5 CCR Tech Rigged

Semi-Closed is less popular for the vast majority because it’s a glorified gas extender with an efficiency ranging from 8:1 to as high as 10:1 efficiency.  They can use the same lung that a life-support patient breaths from which passively allows excess gas to vent from the bottom of the unit while the lung is refilled.

The Passive Semi-Closed Rebreather is very popular for depths where open and closed circuit scuba are less reliable.  PSCR Divers often use larger cylinders.

Fully Closed Rebreathers utilize smaller tanks, a greater degree of efficiency as high as 40:1 that of open circuit because when the efficiency is met, the diver recycles the entire exhaled breath and only has to inject the oxygen when the PO2 drops.  They can be more complicated but are more popular at the time of this writing

Rebreathers ARE NOT For Everyone

With the Cost of Helium increasing, more and more people are looking to breath more efficiently, however, diving a rebreather requires a higher level of awareness, technique, buoyancy, trim, knowledge of the machine and what can go wrong and how to troubleshoot problems.

It’s only a matter of time until Rebreathers become more common practice to the masses, however, now is not the time for most people because they don’t have the training or the experience.

Helium keeps going up and up, but that doesn’t mean unqualified Divers should be jumping in blind and bypassing all the experience and fun that is had learning and logging the experience dives that makes a person a better Diver.

Here are illustrations of a basic rebreather design and semi-closed rebreather design courtesy of the NAUI Rebreather Instructor Guide.

SCR Rebreather
SCR Rebreather
Closed Circuit Rebreather Diagram
CCR

Types of Closed Circuit Rebreathers

Choosing the right rebreather for the individual is key.  There is no perfect one rebreather of everybody.

Automatic: Some Divers prefer an automatic rebreather than much like a dive computer, runs the dive for them setting a constant PO2 (oxygen set point) for them on descent and maximum depth injecting oxygen using a solenoid .

Unless the Diver remembers to set the computer to a lower set point on ascent, this can cause problems for the Diver as the unit will continue to inject oxygen as the depth reduces because as the diver goes shallower, the Po2 will drop, so if the Diver ascends from depth at a PO2 set point of 1.2ata the rebreather will try to keep filling the lung with oxygen, whereas, the diver needs to set their set point lower to 0.6ata and they can ascend without worrying about an out of control ascent and manually adjust their set point to their desired level.

Continuous Mass Flow and Needle Valves: Some rebreathers use what’s called a needle valve which uses a “Mass Flow” orifice on the regulator of the O2 tank. The Diver can set their oxygen set point based on their metabolic oxygen rate by adjusting the Needle Valve.

The needle valve will gently flow oxygen into the counterlung so if the diver becomes task loaded and isn’t watching their Po2 (which should never happen), they needle valve will prevent the Diver from going Hypoxic.

You’ll find the Mass Flow a great option which is why the original KISS Rebreathers are still one of the simplest designs, while the updated Needle Valve design of Fathom CCR  is becoming so popular.

The Continuous Mass Flow system is limited by depth.  The intermediate pressure of the regulator first stage can reach the same as ambient pressure meaning an intermediate pressure in the first stage of 10BAR/145psi will not put out any more gas past 81msw/260fsw.

The Fathom System corrects the by modifying a diaphragm sealed first stage with a stronger spring which allows for safe boosting of the intermediate pressure up to as high as 205psi/14BAR which is capable of diving to depths of 120msw/395fsw.  The pressure can also be increased up to 290psi/20bar for up to 585fsw or 177msw!!!

Excerp from the Fathom Page: “Smaller fixed-orifices can also be used for deeper depths with higher intermediate pressures but the risk of a blockage is increased and the options are limited by orifice availability. A fixed-orifice requires that the first stage intermediate pressure be adjusted to achieve a flow rate that corresponds to the diver’s metabolic needs, typically around 0.6 to 0.8 L/min. Conversely, the needle valve allows the first-stage intermediate pressure to be set to any pressure since the needle valve handles the flow adjustments. More importantly, the needle valve minimizes the risk of a blockage from debris since it can be opened up to allow small particles to pass. The oxygen MAV, which contains the needle-valve, is ported directly into the exhaust side of the head so oxygen must travel through the scrubber and mix with loop gas before reaching the diver.

1 (145 psi/14.7 psi/ata – 2 ata) x 33 fsw/ata = 260 fsw  (Note: always subtract 2 ata when calculating the maximum operational depth of a CMF system.)”

Diving the Bell Island Mine with Explorer and Rebreather Instructor Matt Mandziuk

Manual CCR: Manual Rebreathers are simple, easy to use, but require more attention to the instrumentation and require the operator to constantly inject oxygen based on their needs depressing an oxygen injection button allowing the Diver to adjust the oxygen as slowly or quickly as needed, in a similar fashion to how a diver would inflate their bcd.

When Diving a Manual CCR, the Diver will have to remember to monitor their Po2 and maintain the desired set point.

One of the more fun skills is “Volume Drop” which the CCR Diver will do in their initial training course to see how long it can take their mix to go near hypoxic from their targeted set point.

Keeping a consistent set point that mirrors a backup computer if there isn’t a second computer handset or NERD on the unit is a desired option.

Being diligent with keeping the oxygen level consistent is a must.

Simplicity and Reliability Should Favour Bells and Whistles

The more high tech of a rebreather, the more complacent some Divers get.  Whether you’re flying an automatic or manual system you should always be aware of your set point and Do Your Pre-Dive Checklist!

A Rebreather is a very Serious Piece of Equipment.

PSCR Rebreather
Semi Closed Rebreather Rigged and Ready to Dive with double 80’s in Mexico

A rebreather is essentially a nitrox or trimix gas mixing system that is designed to deliver a constant oxygen set point that acts as a gas extender to you diving more efficient.

With each exhaled breath you make on open circuit scuba, there is no way to get that exhaled gas back.

A rebreather recycles your exhaled air, which is typically 5-6% less oxygen than you inhaled.

When you exhale into a rebreather, you’re exhaling into a scrubber canister, which is essentially a “filter cartridge” that is filled with a carbon dioxide absorbent, a granual that traps the CO2 on granules that resemble kitty litter called Soda lime, which is used to remove CO2 from breathing gases to prevent CO2 retention and CO2 Poisoning.

The filtered gas enters a counterlung that allows you re-breath this recycled gas and as it continues to be re-breathed, oxygen has to be added on occasion to prevent hypoxia (not enough oxygen)….Some have said that a rebreather is “essentially slowly trying to kill you, so maintaining the oxygen levels is essential.”

With each breath in we drop our oxygen PO2 so as the levels drop, we need to add oxygen to “bump” up the levels or the oxygen percentage you’re breathing can go hypoxic meaning you don’t have enough oxygen to sustain life and can go unconscious and die.

White Arrow Axial Rebreather Scrubber Canister
White Arrow Axial Rebreather Scrubber
fathom rebreather scrubber regular and large size canisters
Fathom Radial Rebreather Scrubber by Golem Gear

Think of the Scrubber and counterlung as your cardiovascular system.

Radial vs Axial Scrubber

Radial Scrubber allows the gas to pass through he canister body and provides a lower work of breathing, but is more difficult to pack than Axial Scrubber canister.

As the Co2 Absorbent becomes wet through moisture/condensation, the absorbent can clump, which can make it more difficult for the gas to pass through it, thus increasing the work of breathing.

Axial scrubber size/length needs to be long enough to prevent channelling of gas and short enough to keep the work of breathing low enough.  A longer Axial scrubber will increase work of breathing.

For longer dives, a longer radial canister is much preferred as the work of breathing remains excellent on most designs.

There are also pre-packed scrubber cartridges available for some models of rebreather for the Diver who doesn’t want the responsibility or liability of packing a scrubber canister.  These are more costly, but effective.

Rebreather Fatalities are (approximately) 10 Times More Common than Open Circuit Scuba Fatalities

Diving a Rebreather is very different than diving traditional Scuba. You can’t control buoyancy the same way and they don’t deliver gas the same way. Some even have a very complicated bunch of electronics or bulky, dangling bits everywhere and a huge, bulky counterlung.

Many CCR Divers can’t do a “try dive” on the unit they think they want to buy, so unfortunately, we see many people making Very Poor Choices in their Selection.

Your best rebreather is ultimately the one you think you want, but honestly, the simplest, most reliable and mores streamlined rebreather is the one for you.

Avoid Bells and Whistle’s, and run the unit in “manual” mode instead of an automatic rebreather. Be In Control of Your Oxygen Levels, don’t trust the machine to do it all for you.

Get as polished as you can be and as experienced as you can be before you jump into a rebreather.

Who Should Dive a Rebreather?

If the CCR Diver is wanting to dive the a pair of shipwrecks within recreational limits and dump their scrubber after the dives are completed, the cost of absorbent and gas fills will cost more than Nitrox fill in doubles would, so unless that Diver is planning a longer than “No Stop” recreational time limits, or saving the absorbent after the days diving wraps up for another day of diving, there is no benefit to using a rebreather on those dives, other than practice.

Cave Divers can spend hours underwater just on a single dive, as can shipwreck divers, technical divers and research divers.  This is who a rebreather is best suited for.

NEVER ABANDON HOGARTHIAN/DIR/NTEC PRINCIPLES AND VALUES

Your rebreather configuration should be as streamlined as your doubles setup. Simple, Streamlined, Reliable, Familiar. Long hose is always off the right post, necklace (or BOV)  is always off the left post so they don’t roll closed when swimming through a restriction like a cave or shipwreck.

Most CCR Divers Don’t Mirror Open Circuit (Long Hose, Backmounted Diluent, SPG Left Hip, etc.), which makes the system more complicated and in a situation where task loading can become a problem, that’s never good.

200′ Trimix Dive with LP50’s, argon, Nitrox 50 and Oxygen

You should NEVER have to re-orient your stage bottle rigging (Always Valves Up Not Valves Down), positioning of your stages (Always Left Side). Running your valves “Valves Down” means your regulators are going to hit first when you do a stage drop.  Those diving in the Great Lakes also have to worry about Zebra Muscles slicing into your hoses.  It’s also easier to do a bubble check when your stage bottle valves are facing you.

Valves Up? or Valves Down on the Main Cylinders?  Diving 3L Cylinders you will trim out better with the valves upright like a standard K Valve, but the Valves Down is acceptable for some configurations too.

When Diving CCR with Aluminum 40’s or Faber LP50’s Valves Up is the Most Modern and Most Reasonable Option.

Diving PSCR Valves Up is the Only Option as well, since the cylinders are larger and your’re mirroring your Open Circuit Doubles Configuration.

You can also get a Sidemount Rebreather in PSCR or CCR.  Many of them do not breath well.

Remember the DIR…NTEC Principles are based around the concept of “Doing it Right”.

Not Enough Bailout Gas

One of the most common problems with rebreather divers is that they do not carry enough bailout gas!

You’ll sometimes see a cave or trimix diver doing a technical dive with 1-2 aluminum 40 cylinders.  In the unlikely event the diver is equipped with 3L (FX23 cubic foot) tanks, they should have a minimum of 2 stages.

Some Divers are also starting to use a Sidemount Rebreather as a bailout option.

Cave 1 Divers require a minimum of 140ft3 of bailout, while a Cave 2 level Diver requires a minimum volume of 225ft3.

This means that the average CCR Diver doing a cave dive with an aluminum 40 or a pair of 40’s isn’t carrying enough bailout in the event of a full failure of the unit where they’d be required to swim their bailout from the deepest point in the cave.

Even an AL80, AL40 and the 3L tanks aren’t generally enough for a cave 2 level dive, 2 80’s and bailout in fact aren’t either as that + the 3L cylinders is only 200ft3 of gas.

A recreational diver doing No Stop Diving can use a single AL40 from 40msw/130fsw.

A Technical Level 1 Diver 50msw/150fsw would require an AL80 and an AL40 to ensure they can hit the obligated deco stops ascending from max depth to first deco stops and in the second bottle should have at least a 50% nitrox mix to breath.

A Trimix 1 Diver (2 deco bottles in Open Circuit) generally certified to 60-72msw/200′-240′ should have at least 1 AL80 worth of bottom gas to ascent from max depth to first deco stops. A second AL80 to ascend form the 150-70′ range and then enough gas to get from 70′ to the surface.

A Trimix 2 Diver diving beyond 70msw/240fsw requires enough bailout to ascend from max depth to first deco stop, and then each additional phase of decompression.

A 91msw/300fsw would require roughly 150ft3 of open circuit bailout to the first required deco stop, which would be a trimix of a 21/35 or 23/25.  That would have to last the OC Diver up to the next required deco phase which should be 70′ and 50% Nitrox or a hyperopic trimix like 50/25, while others may opt for a 30/30 trimix breathed up to 20′ which would require yet another AL80 for the decompression phase.

You’ll start to see why the little 3L tanks aren’t enough for deeper trimix dives unless you split the bailout cylinders with your team member(s) to minimize what you’d have to carry.

For “Light” recreational dives, double Aluminum 40’s are a wonderful option offering 80 ft3 of bailout on the back.

SCR Rebreather
Try and Discover Rebreather Experience Today

A pair of Faber LP50’s filled “Florida Style” with a bottom trimix is more preferred for experienced rebreather divers.

For the Same Dive the LP50’s would bring the diver into the 55msw/180fsw range easily, switching to the 21/35, then up to the next deco phase at either 21msw/70fsw or 30msw/100′ and up to the 9m/20fsw phase where another AL80 of oxygen would be required.

It’s so important to plan ahead and plan for the worst, as you don’t want to be left with any surprises, and while a flooded rebreather or a total loss of your PO2 monitoring equipment is rare, which can happen, as can regulator failures, burst disc ruptures and more, but that’s why they call them a failure.  They’re unplanned.

Being Proficient in at minimum of 2 AL80 Stages is why I always encourage Divers to get to at least the Cave 2 or Trimix 1 level.

Maintenance

The pre-dive setup and post dive teardown of a rebreather could take far longer than the planned dive. Some units are easier to assemble and teardown than others, which should be a consideration.

Maintenance, pre-diving evaluation of all components which should be frequently inspected, as well as changing of the oxygen sensors every 6-12 months, servicing the regulators, fittings, o-rings, injection equipment should all be factored in.

If a leak is detected in the unit, it can cause more problems in the event of an emergency, as a flooded rebreather can have an unfavourable effect if the scrubber becomes wet, causing a “caustic cocktail” which can be an instant retching action that can cause the diver to go into a choking reflex as you ingest this corrosive, alkaline cocktail.  If a Diver tries to bail out to open circuit on a separate regulator they may involuntarily inhale more water, while simultaneously retching and possibly drown, this is where a Bail Out Valve or BOV is a very smart piece of equipment.  The BOV has a switch on the rebreather that allows you to open the breathing loop from closed circuit to an open circuit regulator.

The diver will then be able to breath or barf and breath through the second stage as they take sanity breaths for a couple of minutes.  Students are taught to purge empty the rebreather from water on their CCR Course.

Instead of a BOV, some rebreather divers use a DSV (Dive Surface Valve) to allow them to breath surface air topside.  This could be more risky in a caustic environment as the diver doesn’t have the ability to switch off closed circuit to open circuit in the even of a caustic cocktail, so utilizing a necklace under the chin reminiscent of how modern divers dive with a long hose/short hose configuration is the only reasonable option to get breathable gas if the unit is flooded.

People love the “Cool Factor”, but I wholeheartedly caution those who don’t cut it at the recreational or entry-level technical diving level to wake up and seriously ask yourself if you’re ready for all that CCR Diving entails.

A friend of ours who passed away recently ago used to say he never dove a rebreather because he had friends who were Doctors or Lawyers with more letters that were in front of their names who died on them.

Diving a Rebreather is more commonplace now, but unless the dives are super deep (below 150’ or more) or super long like those maybe a Marine Research Diver would be participating in, the reality is that diving Open Circuit is the more efficient choice for the average person.

Rebreathers require a much higher degree of attention, diligence and understanding of how the unit works.  The simpler the unit, the easier it may be to fix on the fly in the event of an equipment related issue.  You should always have multiple ways to receive breathable gas in an emergency, so always do your positive and negative checks, and test out the mushroom valves, regulators, fittings and practice drills regularly to keep your problem solving skills sharp.

Have a well stocked rebreather Save a Dive Kit of spare o-rings, regulator parts, breathing hoses and sensor(s).

Keeping Your Rebreather in “Dive Ready Condition” is a Must.

Pre-Dive Checks, Calibrating the Instruments, verifying flow rates (if applicable), packing your scrubber, then cleaning and disinfecting the unit is all part of rebreather diving.  Don’t be lazy and don’t be complacent.

Diving a Rebreather requires diligence and being familiar with all the inner workings of the unit.

Things to Consider.

Which Side does the oxygen inject in from?  Before or after the gas is analyzed? Does it have an ADV or a T-Block Piece?  How many different ways can you get breathable gas if you need it?  How does the unit breath flooded? Is the unit reliable?  Does it work in cold water or just warm water?  Is it lightweight for travel? Do you need to wear weights with it and how much?  Is the cost of the unit agreeable?

What are the entry requirements to training on a Rebreather?  Agencies who make it “too easy” don’t get the big picture.  Train harder, skill up and then go to a rebreather.  Don’t Take Short cuts.  See my previous blog post What’s The Hurry, What’s The Rush?.

You’re making a decision that can cost you over $10’000.00USD.  Do Your Research, but more importantly talk Us.  We do get Demo Units as well sometimes as trade-in’s.  We currently have a Sentinel CCR up for grabs.

Book a Try Dive with Us and see why our way is the best way.

All too often Divers go blindly into purchasing a rebreather and it’s not until they start putting the hours on their units do they realize they purchased the wrong one.

In Closing

Rebreathers are a lot of fun, as you can extend your dive times, see more creatures up close and more personal, it buys you time in an emergency if you’re trapped in a shipwreck or a cave to find an exit in the event of a collapse making them a safer choice for extreme cave diving and the deepest shipwreck diving.

50-100 Trimix Dives will more than pay for the rebreather and the training, so get your hours up in Open Circuit, get proficient with multiple stage bottles and let’s help you become a Rebreather Explorer.

Vertical Diving SeaHorses Sucking it Up

Diving Dry with Doubles

Diving Dry with Doubles
by
Matthew Mandziuk

Diving Dry with Doubles.  Have you ever noticed that the most active divers on the dive site are the one’s who are Diving  Drysuit with Doubles?  Quite often its the same 10-12 divers who sign up for a lot of the same trips and who often prefer diving together with the group.  The reason for that is comfort, with their kit, with the group, with themselves in the water, whereas the other 10-12 guests are a revolving door of divers with a ranged diving background.

In this blog we are going to talk a little about the benefits of diving Diving a Drysuit with Double Tanks.

By the end of this reading you should have a clearer understanding of the partnership between diving with a drysuit and doubles, the benefits of diving with a drysuit and doubles, some of the training offerings with divers in a drysuit and doubles and where diving in a drysuit and doubles can take you.

Why should you start Diving Dry with Doubles? 

At first it sounds a little much, diving a nylon or neoprene full body suit, hood, gloves and then more weight than we even used in a wetsuit?  Drysuit divers wear approximately 6-8lbs minimum in fresh water (more in salt because of the added buoyancy)  more weight than a diver in a single piece 7mm jumpsuit (or about the same weight as they’d wear with an old school farmer John and Jacket).

That added weight can be inconvenient at best.

Where does one put that extra weight?

Most of our DDS Divers utilize a backplate and harness system which promotes better horizontal trim, posture and streamlining , it’s expandable and fully adjustable to accommodate the drysuit much easier than a jacket bcd can and is far more comfortable.

To learn more about backplates in general, please click the hyperlink above.

Divers diving in Canada with a single tank often times use a stainless steel backplate with a weighted single tank adapter, that system has a total negative buoyancy weighting of approximately 10lbs.  Nearly enough to sink anyone in a 7mm wetsuit with 2-3lbs maximum per side additional, however a drysuit diver is going to require an additional 6-8lbs minimum depending on the undergarments they wear.

In an attempt to  promote proper horizontal trim, the diver will want to re-distribute the weight evenly around the body with a maximum of 4-5lbs per hip pocket and up to that much weight on each of the single tank straps for a total of up to approximately 20lbs of weight plus the backplate system = 30lbs. Doesn’t that seem like a little much?

In an attempt to minimize the weight the diver wears, many will go to a single steel tank which can be 2-8lbs negatively buoyant by todays standards diving with a Faber steel cylinder.

A few years ago Worthington cylinders were preferred for their additional negative buoyancy characteristics with the X7-100 and X8-130 being the 2 most popular options.  In Faber the FX100, FX133 and LP85 are our most popular sizes.  Strangely enough the 100’s and 130’s were also the most suitable tanks for doubling up for deeper dives.

Faber FX100 swings from -8.41lbs full to -0.59lbs empty.
Faber FX133 swings from -9.08 full to +1.45lbs empty
Faber DVB85 swings from -3.8 full to + 2.32 empty

Worthington X7-100 had a swing of -10lbs to -2.5lbs
Worthington X8-130 had a swing of -11.7 to -2lbs

Having a tank that is negatively buoyant allows divers to reduce overall weight required and keeps some of that negative buoyancy behind you which helps improve your trim rather than having all that weight on the hips, but you don’t want to overweight yourself with tanks too heavy and underwear too thin.  Try and find the balance.  Many divers will even favour aluminum tanks for shallow shore diving with thin garments.

Adding an extra tank minimizes or eliminates the need for additional weight while adding a safer configuration that builds on our progressive single tank system utilizing a long hose/short hose and spg on 24″-26″ HP hose and it gives divers  the ability to solve a catastrophic failure thanks to redundant regulators.

Aluminum twins are popular option for divers looking for a great wetsuit set that can be used with a drysuit, however, they are more suitable for use on shallow dives.  When worn with a drysuit the diver will have to wear a heavier steel plate, a v-weight with lead down the centre of the tanks and a compact and streamlined wing.  They are easy to dive with little learning curve.

Steel tanks will take the diver further through deeper dives, caves, wreck penetration and offer more reserve gas on the divers back to deal with emergencies.

Vertical Divers with all the weight on the waist in a jacket bcd with dangling everything
DDS Diver John displaying perfection with great trim, buoyancy, control and style as he swims around the Tugs in Tobermory, ON

Many divers prefer the additional gas capacity of the steel tanks as well as the larger sized tanks allow divers to dive deeper and stay longer in comparison to the standard aluminum 80 tank which is still the most popular scuba diving tank on the market.

 

Drysuit Divers and DDS Divers have better trim because a drysuit surrounds the entire body with a little bit of air (less is better).

Redistribute weight, minimize weight and enjoy easier diving.

 

As divers tend to dive more off the dive boats and spend more time on their favourite dive sites, divers start looking at how to get more bottom time.

Diving Nitrox allows divers to gain up to 50% more bottom time on sites around 100′ and deeper, while yielding even more bottom time shallower, however, the limiting factor at that point tends to be their breathing rates and the sizes of tank they use, so a steel tank will in fact increase their bottom time an allow them to achieve their dive plans up to the Nitrox NDL most dives.

For divers who find even on Nitrox, the NDL isn’t always long enough, extending their range into decompression diving often is the trick, as a diver learns how to properly and safely plan their dives with a little bit of decompression utilizing advanced nitrox mixes to accelerate decompression times.  This is where doubles are most beneficial.

DDS Divers practicing bottle handling

When a diver combines the drysuit for maximum exposure protection and comfort along with a set of twin tanks, they no longer have to worry about switching out their tanks on that rocking dive boat in between dives, they no longer have to worry about adding weight to their hips or anywhere usually on their body, and they can certainly benefit from the increased balance and comfort that doubles offer.

You’ll also find divers enjoy just going out and working on foundational skills is easy to observe as our divers are always out in open water honing their skills.

Diving Dry with Doubles allows for more even balance in the water as the tanks are placed over top of each lung rater than down the spine like a single tank, while giving the diver a more comfortable suit to don and doff.

Drysuits are easier to put on than a 5-7mm wetsuit.

Drysuits are more effective for warmth retention.

Crushed neoprene or trilaminate Drysuits don’t compress with depth like wetsuits which get thinner with each atmosphere making the diver heavier because of the initial weight they start the dive with, as well as making the diver colder because those thick suits become much thinner every 30ft/10meters they descend.

Are Doubles For You?

If you can carry them on your back, reach your valves and dive with them comfortably, the answer is yes!

 

Look at the number of  accidents that have happened in recreational diving situations with single tanks, especially on deeper dives.  Most recreational diving accidents occur in a single tank with no redundancy (pony bottle, sidemount, h-valve, doubles) or lack of training.

A diver breaths their tank empty, their buddy runs out of air and they didn’t reserve enough gas for them and their buddy to ascend, they went in cold water and the regulator froze up, they hit the regulator or tank valve off a shipwreck or overhead environment creating a catastrophic failure, the BCD freezes, their dive computer blows off the end of their high pressure hose (another reason to wrist mount your computer) so they panic seeing bubbles streaming out of the high pressure hose, etc….

Minimize the risk, Increase the Fun and Learning and be more mentally and physically prepared with more advanced training.

If you’re interested in diving deeper than 80′, cavern or cave diving, technical diving, ice diving, mixed gas diving or wreck penetration, you should do it on doubles.  To many people did it wrong and it cost them their lives.

Be the best diver you can be.  Get involved with DDS and we’ll make you the best diver you can be with our training, experience dives, trips, charters and exploration offerings.

We’ve found these factors to be some of the most beneficial tools to extend your diving into a more fun and exciting world:

Dive Planning: Plan Your Dive, Follow Your Plan, Have an overplan, bailout plan, but don’t deviate from the main dive plan

Gas Management: 1/3 down and around, 1/3 back, exiting water with 1/3 of your gas supply 

Redundancy: Doubles allow the ability to shut down your regulator in the event of a failure, free flow, freeze-up, burst disc failure etc. Isolation manifold allows to shut down and switch over by isolating and shutting down the offending post or just shutting down the offending post.

Narcosis Management: Don’t Dive Deep On Air.  You’re narc’d at 130ft/40meters whether you know it or not.  Don’t dive deep on air, it’s silly, outdated and unsafe with education and helium training available now.

Team Diving: Serious Diving requires divers you can trust in an emergency and in an pinch. Don’t just dive with the randoms you find on a boat down south, they’re usually once a year divers with horrible habits and inferior training.  Dive with divers you have a positive history with or as ask us and we can refer you to more progressively minded shops

No Solo Diving on Deep Dives: Solo Diving is popular now, we’d likely choose this option if diving south with random divers instead of having to buddy up with people that we don’t feel comfortable diving with, however, deeper dives require piece of mind, extra equipment and a proper plan with lots of “what-if’s” to be safe guarded against.  It’s not worth solo cave, solo deep (exceeding NDL) or solo overhead environment without buddies

Analyze Your Mixes: Always, Always, Always analyze your mixes when you pick your tanks up, make sure they’re labelled and if diving with a fill that was “just filled” and you have to grab and go, analyze it again before your day of diving begins.

Practice , Practice, Practice: Complacency Kills.  Work on trim, buoyancy, bottle handling, dealing with simulated emergencies, smb deployment, alternate fin kicks, etc.  Be the most polished and best diver you can be.

Fit is Everything

Don’t just jump into drysuits and doubles blindly.  It requires the right fitting suit and undergarments first and foremost.  Many brands of drysuits are inferior in fit and quality, even the brands offering “custom fit”.

You’ll notice most shops try and pedal the cheaper suits that are like garbage bags or garbage bags wrapped in lycra to cover up the garbage bag look. This is like buying a drysuit from McDonald’s!  Don’t Waste Your Money

If you truly want to LOVE your drysuit and want to enjoy using it, take the time to get properly measured and properly fit.  Don’t just let the dive store hand you a suit off the rack and tell you that it’ll fit you perfectly, we’ve had that happen to several students from out of town that couldn’t complete their required skills during Intro to Tech Training and ended up renting suits from us to finish the class, then ultimately buy a brand new suit from us.

Do it Right.

We are partial to Diving Unlimited International because they offer the best quality, service, workmanship and there is an actual after sales service with them.  They are our top choice for hard to fit people too.  It’s all about comfort and fit with them.

DUI have great value priced suits with their Coronado, San Diego and Yukon II suits and the new Cortez (2019) suits obliterate most brands “top of the line suit” for quality, features, performance, as well as coming with user replaceable quick change ZipSeals, meaning you don’t have to send the suits away for service unless you damage the suit or zipper!  No brand can compete with that!

Santi offers a great quality and great looking suit.  We do their stock and modified stock suits.  You’re allowed up to 4 alterations at no extra cost with them and they do offer custom too.  Suits are very tough and stylish with a beautiful Euro look of elegance and colour.  They do take some time 2-3 months typically (sometimes less sometimes more).

Fourth Element offers the most flexible drysuit on the market.  It’s durable and looks great and they’re using technology to their advantage instead of dive stores who can miss measure someone by using BIOMAP technology to digitally create an image of the person to cut the suit for.  Great suits for a great price with great service…it might just take a bit more time to get the suits made 2-3 months typically.

BARE offers a great stock suit at a good price depending on what you get with the suit from your LDS.  Just but it from DDS and you’ll be happiest.

The Drysuit Underwear is as important for fit and mobility as the drysuit itself.  Santi offers modified stock and custom underwear, DUI offers DuoTherm ultra stretch polartec suits for custom fit as well as a great selection of stock sizes in up to an XM450 material which is exceptional underwear for cold water.  Fourth Element offers an amazing range of suits for a range of conditions made with some of the nicest feeling and fitting materials.

Learn more about diving doubles by stopping in or sign up for a Discover Doubles NTEC night with us.  

NTEC will introduce you to the doubles configuration, foundational skills you should master, emergency drills and more. It’s a perfect prep-workshop that introduces divers to the principles that will help lay the groundwork moving forward towards more regimented training with the right guidance, education, exercises and more to help ready you for our NAUI Intro Class.

Our NAUI Intro to Tech Course is a Rudimentary Elements of Diving Course that will highlight the foundational skills and develop them from a recreational perspective that will dovetail into more advanced and technical diving activities and show recreational divers a preview of what their diving can be like by testing and honing a divers finesse, comfort, trim, buoyancy, effortless skills, problem identification and reactions, team diving, smb deployments, buoyancy refinement, fin techniques and so much more.

2 divers swimming across an old wooden shipwreck
Tiller Wreck, Port Dalhousie

NTEC and Intro are the 2 most exciting, modern, challenging classes that will help improve your skills and enjoyment in the drysuit the most. Tie in NTEC and your PADI Drysuit Specialty Course together and see diving with a  different mindset than what you’d hear/see/learn in a traditional PADI system of diving education.

Diving Dry allows for longer bottom time in cooler water or more dives per day. A more comfortable gear up experience from a boat.

When you look at our DDS dive trip pics on Facebook or Instagram you’ll notice aside from a pool or an open water course weekend, the majority of the divers you see on our trips and con-ed classes are all in drysuits and you’ll notice that a lot of the same divers come out year after year on our charters and trips because their level of enjoyment is substantially higher than a wetsuit divers.

A friend of ours had a shop in Massachusetts and they trained their divers exclusively in drysuits.  They offered by far the most expensive open water course from NY-Maine and everywhere in between, yet their continuing education rates were 400% vs a national industry average of about 25% of divers who go diving and train after open waters.

So they found enormous success training their divers and promoting colder water diving trips because like DDS, they realized the best diving in the world was around the Great Lakes, Atlantic wrecks, Florida and surrounding areas. They were right.

In Closing

Drysuits will last you longer than a wetsuit, will give a diver buoyancy control that is easier to maintain when you where a little “squeeze” on the suit vs a wetsuit which compresses and changes depth the deeper or shallower you go.

Drysuits will allow for colder water immersion and more dives per day, while in between dives the divers will warm up faster, so the energy that is rejuvenated is much higher, especially with todays’ warmer Thinsulate’s and heated systems.

Combining a drysuit with a set of doubles sets a diver up for a lifetime hobby where anything is achievable.

The divers can spend more time under the water enjoying their hobby.  They don’t have to change tanks awkwardly on the boat in between dives like single tank divers do.  They add a larger gas source to deal with emergencies such as low on air or an equipment failure, while also adding redundancy in the event of a regulator or valve failure.

Aside from a little extra weight on land, there isn’t much difference between a single tank and a lot of lead to sink a recreational diver and a set of doubles.

For divers who can’t wear a set of doubles, try Sidemount!  Sidemount is a great option for divers who don’t have the ability to reach back to shut a valve down or who have had back surgery or a physical limitation that negates the ability the wear doubles on their back.

At Dan’s we believe in a more fun progression, so training our divers the right way from the very beginning is so imperative and gives them so many more options moving forward beyond Open Water, Advanced, Drysuit, Rescue, Divemaster and Instructor.  Don’t get caught in the boring progressions that the recreational agencies endorse, there is a much more fun, challenging and enjoyable progression ahead.

Experience more in the world of scuba diving instruction with Dan’s and let us show you a better way to do things that makes more sense and creates better divers.

Dan’s is an innovator of progressive recreational and technical diving, bringing the most modern skills and philosophies forwards before anyone in Canada as we continue to lead and offer the highest standards and most exceptional dive training for recreational and technical diving and have helped shaped some of the finest explorers in the world of scuba diving too.  Train with Dan’s and see a brighter diving future.