'Open Water' only sidemount BCDs: Your opinions?

[drrich2]

Yes, I'd want to be horizontal to dump air from it, but in sidemount that's normally the most comfortable way to be.

Glad you posted that since it brings into focus a question I have. Like many OW divers who've never tried side-mount, I typically ascend and descend vertically; on ascent I hold my low pressure inflator high & release air as needed to keep the rate slow and buoyancy where I want it.

I'm guessing most side-mount divers ending dives don't maintain a horizontal hover all the way to the surface. How easily does the 'cave style' model vent as you ascend vertically?

Richard.

 

[Jim Lapenta]

I don't dive sm either yet but rarely ascend or descend more than maybe five feet vertically. And that's only in places where there may be boat traffic. Back mount or side mount you have butt dumps or even shoulder dumps to use for horizontal ascents. I don't touch my inflator till I'm on the surface. Horizontal is much easier to control rates and should a runaway ascent occur for some reason like a sticking inflator you are already in a flared position to address it. I hate descending vertically. Like to see what's under me. Especially in low vis. And horizontal descents are much easier for new divers to control once they've been shown how. In fact it's the first descent technique they are shown in my open water classes.

Sent from my DROID X2 using Tapatalk 2

 

[Colliam7]

I'm guessing most side-mount divers ending dives don't maintain a horizontal hover all the way to the surface. How easily does the 'cave style' model vent as you ascend vertically?

Maybe I have been doing it all wrong (I don't think so, I but I try to be open minded). I don't ascend vertically when diving SM (or BM), except possibly the last 5 feet when I am moving to a boat ladder, or I have reached shallow water on a shore entry / exit and am ready to stand. I dive an original Nomad (which, I assume, is viewed now as an antique), or I dive an OMS Profile. The beauty of a SM rig is the stability it offers in the horizontal position - not unlike a pontoon boat. As I ascend, it is comfortable to remain horizontal - to purge air all I have to do is roll slightly to my right, to move the shoulder dump higher.

As for new rigs designed for 'open water only' - that presumably is a growing market, as more people decide they a) want to try SM, and b) prefer SM to BM for doubles diving. Perhaps, a number of people who ant to try SM think that a 'cave' BCD, like my Nomad, is somehow 'wrong', 'bad', or not appropriate. My Nomad works just fine for OW. My Profile, attached to a BP/W, works fine for OW (and frankly is not as well suited for tight spaces). I guess I need to see what some of the OW-only rigs look like, in order to understand why this gear is coming into the marketplace.

 

[DevonDiver]

Who gets to say how a configuration should look or how it should be used? Is someone claiming to be the font of sidemount DIR? If OW divers want to configure in a certain way for their environment what basis does a cave diver have to criticize?

In this case, the laws of gravity and measurement gets that say-so. The issues are:

1) Cylinder and diver stability. Horizontal trim is demanded in sidemount by the necessity to retain stability of the cylinders. Cylinders hang at the divers' sides, and are not clamped on their back. Movement from horizontal position causes cylinder movement and more drastically effects the divers' stability. It differs to back-mounted diving for that reason - and this necessity has been reflected in the training standards of every agency that provides sidemount training. For instance, sidemount is the only recreational PADI course that specifically guides instructor towards developing horizontal trim.

2) Equipment Configuration - Hose Routing - Sidemount cylinders are secured in a different location to where backmount cylinders are secured. Go figure... common sense eh? Top-mounted LPIs are absolutely logical for backmounted diving - they provide a direct, efficient routing of hoses from regulator to LPI attachment, with no need for the LPI hose to be bended or re-directed in any way. In contrast, sidemount cylinders aren't secured on the diver's back - they are under the armpits. That means an LPI hose is routed from the opposite direction. That requires a different approach for LPI hose location - if the same results of direct, efficient LPI hose routing are to be achieved.

btw... for clarification, I am not a cave diver, but I am a sidemount instructor..

On cylinder stability and the need for trim.....

4. How do you adjust for proper trim in sidemount? What are your options for refining your trim during a dive?
E. Proper trim in sidemount.
1. You need optimum trim and streamlining to move cleanly and efficiently, which saves energy and gas. Streamlining reduces damage to the environment because you’re not dragging gear across sensitive aquatic life.
2. On your first sidemount dives, your instructor will have you establish neutral buoyancy.
a. Relax and hover. See what your natural attitude is in the water (horizontal, feet high, low, etc.).
b. Your buddies and the instructor will help you be sure your cylinders are relatively in line with your body (you can’t always see them on yourself).
3. Because sidemount is designed for proper trim and streamlining, you may find you need little or no adjustment after you kit up. As you use gas, however, you may find it changes. Your trim may become more head-down.
4. Regardless, as necessary, to adjust for proper trim and streamlining, arrange your weights so you can hover horizontally with little or no effort, and so you can easily change positions during the dive. Arrange your cylinders so they’re inline with your body.
5. Changing cylinder attachment points and sliding weights up or down on the cylinders (if you have weights on them) can help.
6. It may take some practice initially, but usually becomes intuitive quickly.

Section 3 - Open Water Dives
....
10. Hovering
a. Demonstrate the skill.
b. Students establish neutral buoyancy and hover for at least one minute.
c. Encourage hovering in a horizontal, swimming position.
....
11. Ascent and safety stop
a. Students ascend in buddy teams and make a three minute safety stop at 5 metres/15 feet.
b. Encourage maintaining a relatively horizontal position and keeping stop depth at chest level.

Then, we see...

Sidemount diving is not a new concept, but its application has spread from cave diving to open water recreational and technical diving. Sidemount diving presents divers with adifferent approach to equipment configuration, and a new set of skills to master.


Remember that the philosophy of this course is to provide an introduction of the benefits and proper configuration of the use of sidemount equipment for recreational diving, with
an emphasis on safety.

Sidemount is different to backmount. That's pretty fundamental. Pushing divers towards a belief of retaining back-mount configuration aspects detracts from the overall benefit of sidemount. It's nothing short of a lazy approach. It's different...and requires a different approach. That's why training is given....

Specifically on configuration...

4. How do you configure your right and left side regulators for use when sidemount
diving?
D. Regulators and regulator configuration for sidemount.
1. In sidemount, the regulators mount on the cylinders so that everything is streamlined without loops or protrusions that cause drag and snags. You rig the regulators and cylinders so that when worn, the first stages are inward, toward your body where they’re protected yet accessible

Maybe someone can explain how a top-mounted LPI achieves the concept of "without loops or protrusions' better than a bottom-mounted one? Bearing in mind that the LPI hose routes upwards from the regulator under the left armpit (rather than downwards from a back-mounted cylinder).

Top-mounted LPIs require a 180 degree bend in the LPI hose. That is, IMHO, contrary to the philosophy taught on the course. That isn't cave or open-water specific - it is a general principle that applies to sidemount diving in all aspects, as a motor-skill and configuration issue.

---------- Post added February 9th, 2013 at 07:42 AM ----------

How easily does the 'cave style' model vent as you ascend vertically?

Piece of cake from horizontal. Bad from vertical.

It's as 'different' as learning to use the lower dump-valve on a BP&W or jacket BCD, rather than relying upon the LPI hose. Actually...it's easier... because most (nearly all) sidemount BCDs utilize a simple air-pocket design for the bladder - which optimizes the ability to dump from a horizontal position, from a lower mounted dump location.

From my perspective as a sidemount instructor: If a diver learns to dive (inc ascent/descent) in horizontal trim, they graduate training able to utilize any model of sidemount BCD. If they are permitted to use a 'open-water only' sidemount BCD...and further permitted to lapse from proper trim whenever they feel like it... then their training has only prepared them to use those styles of 'open-water' sidemount BCD. They will be deficit in skill and technique to use the majority of sidemount BCDs on the market.

For those that don't (yet) dive sidemount: Sidemount is very stable in a horizontal position. When moving into a vertical position, there is more inherent instability in the cylinders - because those cylinders will move around in relation to the diver. At the end of the dive, if the cylinders are 'floaty', this can cause significant instability and cylinder 'rise'. From my experience as an instructor, this places a consequent demand on the diver, who will struggle to control their rig and feel much more 'uncomfortable'.

 

[MSDT476614]

As Devon said it was. Just like how back plates / floats came into the rec world. Seepage from the dark side ......

And another equipment / course marketing opportunity for the agencies to sell certs / books / DVDs. And of course income for the instructors.

 

[DaleC]

Lazy approach? It's recreational diving, not a contest. This reminds me of the tech diver who thinks the rec diver is "doing it wrong" because they use a pony instead of doubles. I think the error is in the rigid mind that can only see one way of doing things.

I must be a poor sm diver then because, although I dive horizontal as a general rule, I am able to go vertical, inverted, sideways and even face up if I want to. Probably I need formal training so I can only dive horizontally.

My wing inflator comes over my shoulder where it meets the short LP whip from my left tank that is routed under my shoulder harness. This causes the inflator to veer towards the center line of my body where it sits for easy use. Easy to locate and streamlined. I ought to take a course so I can see why that's a problem too. Unfortunately, I am too busy diving sm to take a course to learn how to dive sm ATM which is why I am not overly confused or disturbed by these issues.

I haven't vented via my inflator for a couple of hundred dives now. I dump from my hip and can remain horizontal as a result.

---------- Post added February 8th, 2013 at 05:34 PM ----------

and I shake my head when someone else's buoyancy issues affected your ballistic levels when you are filming. Who gets to say how another's buoyancy skills should or should not be when you are filming?

Hey, I'm primarily a solo diver and usually frequent isolated sites. I don't really care how someone else dives.

 

[Dive-aholic]

I can see both sides here. The new rigs have no place in an overhead environment. From what I understand, sidemount divers started moving the inflator hose to the bottom of the wing and the exhaust to the top because the elbow was too fragile and having it on top increased the risk of it breaking when contact was made with the cave ceiling. I've seen a couple of these elbows broken. Putting it under the wing on the bottom protects it. The exhaust cover is pretty robust and I've scraped mine against a few ceilings in tight passages and it's just scratched but still in one piece.

So why would the manufacturers put this back on the top of the wing for OW divers? Well, my guess is being that they are being marketed for open water there is no concern about the elbow breaking because there is no ceiling to impact. Why not just use the original configurations? Well, both of these rigs only have dumps on the inside bottom of the wing. The only way to dump the wing is by getting the bottom of the wing higher than the top while pulling the string. I don't know about anyone else, but when I'm diving in the open ocean and I'm ascending, I'm ascending head up so I can see what's above me. Even with a dive flag there is usually boat traffic. And I can't see the boat traffic if I'm maintaining perfect horizontal trim. While horizontal trim is important in caves and wrecks most of the time, it's not the only way to dive. When I'm descending down a fissure or up a fissure I'm vertical, either head down or head up. When I'm moving down a level in a wreck or up a level, I'm vertical again. When I'm making an ascent in open water I go vertical until my first stop then I'll usually turn horizontal again if it's a long stop. If it's a 1 or 2 minute stop then I usually just stay vertical. Why expend the effort to change positions? So, I do understand the benefit of these rigs for open water diving. They are easier to dump as an ascent is being made.

 

[rjack321]

My pull dump works fine on my shoulder. At first it was a bit fast but I've gotten used to it. I never dump from the LPI at the bottom of the wing, I suppose I could but it would be a bit of work. In other words all the modifications proposed by these manufacturers are hooey. A "SM" BC works fine in OW.

 

[ffdiver]

Just a reminder, the majority of SM gear out of the box comes with the LP hose coming off the top. Just thought yall should be reminded of that before you start complaining about it. All nomads except the JT and the Hollis SMS 100 come that way. It's a choice to change it over like the way alot (not all) SM divers have them. You can still be in a horizontal position and dump air with the LP hose coming off the top, unless most of you have forgotten what it's like to dive backmount or regular ow gear.

 

[Paul S]

So I've been thinking about this a bit more and looking at the rigs again. I still see no reason an LPI needs to be at the top for open water. I can be in whatever trim works in open water, but I do think only being able to dump gas from the bottom of the wing in restricted environments is a problem.

Caves and wrecks are environments where you may follow a narrow passage vertically, need to back up or just control an ascent and be unable to turn to get a low dump to work. You want two methods of dumping. One low, one high; one left, one right.

I can't see any other dump valves on these "cave" rigs. If true I think that's more of an issue than where the LPI is in shipped configuration.