You're choosing your gradient factors wrong...

Sun, 20 Sep 2020 12:26:35 -0500

Choosing your gradient factors (GFs) is a contentious subject for new and experienced technical divers. . If you do, and you’re not confident in the numbers on the computer, then, welcome to the club! I want to break down some common misconceptions about what constitutes a good idea when choosing gradient factors.

If you don’t have a good grasp on what a gradient factor is check out this resource:

Learn about GFs

“Someone else does it [and isn’t getting bent]”

“Not getting bent” isn’t a great metric for choosing a gradient factor. In fact, it's a horrible metric as it can easily lead to serious normalization of deviance. Another person not getting bent is an even worse metric. How many successful dives (no DCS) were made on Haldane, Workman or Buhlmann tables? Lots! How many “extreme” dives have been conducted with no ill effects on “aggressive” profiles (higher gradient factors)? Conversely, there have been plenty of “normal” dives done on “conservative” profiles (lower gradient factors)*. There’s more at play than just a choice of gradient factors

“I feel better after the dive now that I use XX/YY”

There is obviously a range in which this phrase is valid. If a diver is extremely fatigued after every dive and they do more decompression and they are no longer fatigued, that sounds like the right move. But, this statement in general is attributing a change in arbitrary feeling to gradient factors, when that probably isn’t the major contributor. In my experience this is typically the result of someone deciding to change their GFs and then, because they just changed something, begin to pay more attention to how they feel after a dive. Other variables, like predive fatigue, hydration, thermal stress and diet probably play a much bigger factor here. The other problem with this line of thinking is that we’re using our bodies as test dummies. While decompression isn’t an exact science, the idea that you can use a nonspecific highly variable factor as a test parameter is pretty silly.

“As you dive more you figure out the correct gradient factors”

See above. Unless you’re getting bent after diving (and considering the amount of different stressors, even then really) this idea of dialing GFs as dive experience increases doesn’t make any sense. As dive knowledge increases is completely reasonable, but not as dive ability increases.

Decompression Stressors

How should you choose a gradient factor?

Here is the ultimate question. The short answer is: Eh, there’s nothing set in stone.**

The long answer is: You need to be educated on what a GF is, what it’s based on, and the research that backs up low VS high methodology without ignoring the other factors. It’s every technical diver’s responsibility to understand these factors and mitigate them to the best of their abilities.

*Aggressive and conservative profiles are in quotations as a lower gradient factor isn't necessarily a more conservative profile.

** While nothing is set in stone, there are important recommendations to mitigate risk. This sentence is not designed to imply that GF selection doesn't matter.

All Divers want tech gear: BPW

Tue, 08 Oct 2019 17:43:08 -0500

Back plate and wing (BPW) setups aren’t just for technical diving, and haven’t been for a long time. Divers and dive centers have been selling these setups to novice divers for years and many rental fleets are now solely populated with BPWs - but why? Let’s take a look at some of the benefits to dive centers, divers, and bust some common misconceptions.

Benefits to dive centers

Expanded offerings

The majority of customers walk into retail stores with their purchasing decision already made. That’s a fact of modern retailing. Customers see BPW systems online with rave reviews. If you don’t have them in stock then you won’t be prepared to make the sale.

One size pretty much fits all

Harness are either oversized or adjustable to fit a wider range of divers. That means less money tied up in inventory costs for BCDs.

Customization

Wing colors are often customizable allowing your customers to add their pizazz to the system. Backplate material/weight and the location/style of weight pockets are other customizable features that allows one BPW setup to be individualized, something a regular BCD can only do with color options.

Unparalleled in the rental fleet

Dive stores that switch to BPW in the rental fleet all have the same reaction: “why didn’t we do this sooner?!” Pair a BPW with subgravity sliders and it can go from a small to a large with minor adjustments. That means less money in the rental fleet, less to service, and less time trying on different units. Cold water training sites pair perfectly with thicker steel backplates and require less weight to be lugged to the dive site.

Why divers love them

Simplicity

Less to wash, get tangled and transport. The simple harness and wing takes up less space on the boat, in the dive bag and on the diver. Divers love how easily

Comfort

Most BCDs have 3 points of attachment - waist and two arms. BPWs have a 4th, the crotch strap. This contact point snugs the system to the diver so they operate as one unit.

Customization

Want a colored wing? A d-ring in a specific place? A heavy backplate and no weights? It can all be done with a BPW setup.

Misconceptions:

BPW setups are only for tech divers or people that want to be tech divers.

FALSE: The market shows this to be totally incorrect. Photographers, entry level divers and pros alike all love the simplicity of the harness system, comfort underwater, and versatility of their units.

BPWs are difficult to size.

Mostly false: Older systems were difficult to size because of the webbing quality and lack of instructions. Now that harnesses are mainstream the quality of material and instruction makes it much easier. Pre-built systems make assembly even simpler.

BPWs are uncomfortable at the surface.

Mostly false: If you use the system wrong it won’t be comfortable. Fully inflating most wings doesn’t work the same way as a jacket. Inflate the system enough to float comfortably and it’s even more comfortable that a jacket. The crotch strap keeps the unit snug and floating is significantly more ergonomic.

BPWs are deadly because of how they float at the surface.

Very false: Can a BPW float you head down at the surface? Of course they can, but so can jacket BCDs. Look at the inside of any jacket style BCD and you’ll see a distinct warning that it is not a life saving device. This myth’s origin is mostly from a misunderstanding of use. Furthermore in an emergency a harness can be sliced away significantly faster than a jacket.