Shoulder pull dump valve, y/n

[Nemrod]

Nem, In a perfect world everyone would have to time to dive enough to perfect all of their skills and equipment. I work very hard at my skills on every dive but just do not dive enough to be the perfect diver I would like to be. There are tons and tons of things I would like to master but have to focus on just a few on each dive.

In the mean time while learning to dive my DS, getting use to BP/W and diving cold for the first time I will have to be less than perfect by using my BC for bouyancy and relying on some equipment to assit in what I am not good at yet, at least until I can work on those things. I know your not directing your post at me in particular, well maybe you are, lol. It's all good until we get to where we strive to be as a diver. A good day for me right now is being able to suit up with the new DS and not forgetting to install the equalizing tubes in my gloves, getting in the water with no leaks, dropping down with out to much incident and being able to hoover a little off the bottom with out being a rototiller. Maybe working on getting my bouyancy worked out between the suit and the BC. If I am real lucky that day I might find an old bottle.

Best Regards

Nonetheless, I maintain that you or they (?) are using the dumps incorrectly, I don't buy into feet first decents either so therefore I don't see why a shoulder dump would ever be used except perhaps when ascending, and there I just push the vent button on the inflator mechanism, I don't pull on anything. From quickly scanning the replies, most seem to prefer the rear dump on their wings as do I. The only time the inflator hose is well positioned for use in dumping air is when ascending unless you roll that shoulder up, which can work well. Even during the horizontal cruise portion of the dive, the rear dump is the main adjustment point. Perhaps I failed to understand your question or statement. Most wings don't have a pull knob shoulder dump, there is only the rear dump and the inflator hose dump (the push button--no pulling), there is no additional pull knob shoulder dump, perhaps that is where I don't follow you.

What is this perfection thing you got going on? Good luck, hope it all works out.

N, I swim down, I swim around, I swim up

 

[Scott M]

Nem, I completely understand your reasoning and where everyone is coming from with how to properly dump air. I strive to do this also and most of the time can accomplish this. What brought about my original questioning for asking about the pull dump was because of an incident I had recently with D.S., where a pull dump would have been idle to handle the issue. I realize it is my lack of skills with the suit that caused the issue to begin with but in a high stress situation accommodating gear can sometimes be an advantage. I do not dive enough to be perfect with the suit but would like to continue diving it into the fall and winter and a pull dump could help me get to that point.

I would some day love to swim down, around and up but at this point in my diving progression I do not see that happening.

 

[NadMat]

I don't understand what you are talking about actually. When I SWIM down, descend, I vent air (why is there any air in the wing anyways, I empty mine, suck it flat before I enter the water) from the rear pull dump on my wings because I am swimming down, head first, feet up propelling me downward. When I am horizontal during the "cruise" portion of the dive I vent usually from the rear dump if I accidently hit the inflator to long or over adjust. I do that by rolling to the side and tucking my head down slightly. When I swim up, head first, I vent using the inflator hose and I generally do not need to free it from the D ring bungee to vent effectively, roll that shoulder high if need be. I also pre-dump some of the bubble through the rear dump before beginning my ascent.

A good day is when I never have to put any air, none, NONE, in the wing from beginning to end of the dive. That is a goal. I dive as if I had no BC. I swim down, I swim around and then I swim up, swim is the key.

These feet first decents like I see people doing now often result in them being blown off by current, swim down, swim to the wreck, reef or whatever, no feet first stuff, how can you see where you are going?

N

sounds like a lot of swimming to me I prefer to float along neutral, which is impossible without some air in bc/wing until end of dive.

Feet first starts are common if you start the dive positively buoyant and talking with buddy. Unless there is a great need to get down quickly(currents usually) I prefer to start the dive positive and when ready to descend I dump from pull dump on inflator till I get a bit neg and then go horizontal for rest of descent and most of rest of dive using rear dump. I agree that once you get under the water you need to get either horizontal or head down and not drop to bottom feet first, vis around here would usuall have your feet hitting bottom before you could see in that position . I also usually stay horizontal on ascent till past safety stop, maybe all the way to surface if in a protected body of water.

Also, I dive with lots of newly certified divers at local watering holes and starting off negative is usually a bad choice and good way to loose that newbie on way down. I only do negative entry's with a regular dive buddy I know is unlikely to have buoyancy, equipment, or ear clearing issues. JMHO,YMMV

 

[battles2a5]

I'm with the others, I don't have a need for a shoulder dump. I do all my dumping with my rear dump. I also keep my inflator tucked under some webbing that is attached to my d-ring, so it is a PITA to use to dump anyway. These arguments apply to diving that involves more equipment, but could apply to standard recreational diving. But, there are a few other reasons for not using one, other than technique and the possibility of pulling the corrugated hose off:

1. The back-end of the pull dump screws on. There is a story in "Diver Down" about a dude getting in big trouble when he failed to check this and it popped off, leaving him heavy in the water and with no way to gain nuetral bouyancy. It's been a while since I read that book, not sure if he made it or not. If this happened during the initial descent with full doubles, you are going for a ride.
2. The dumping mechanism has a flapper valve that let's air escape, similar to the purge in a snorkel or the exhaust valves in your second stage. If you are venting you could get some some debris clogged in the valve and it could compromise the wing's ability to hold air. The rear dump shares this failure mode as well, but no use in adding another.
3. If you are slinging bottles, you could pinch your inflator between stages and they could cause the wing to dump. This is essentially the same failure mode as the ball on the end of the butt dump. This can be easily resolved, but could be an issue in a tight, silty environment. Also a good reason to use a shorter corrugated hose as well (most are wayyyy too long).

None of these thing SHOULD happen with good technique, equipment checks, and situational awareness, but I don't see the need to introduce the possibility for something that I don't need.

 

[Walter]

I prefer to float along neutral, which is impossible without some air in bc/wing until end of dive.

Actually, it's quite possible. I do it on most of my dives. Proper weighting is essential.

 

[NadMat]

Actually, it's quite possible. I do it on most of my dives. Proper weighting is essential.

to be neutral at end of dive means you are several pounds negative at minimum at beginning of dive. While it is possible to overcome this by breathing technique using lung volume, why wear the bc if you don't use it?

Of course, some of my favorite dives were with just tank, harness, and reg, and swimsuit, and I did use breathing to maintain buoyancy, but I find that with larger steel tank and/or wetsuit the greater shift in buoyancy makes it preferable to use the B (uoyancy) C (ompensation) to keep me neutral and allow me to breath more normally. JMHO, YMMV

 

[TSandM]

Whether you can dive without using your BC or not is going to depend a little bit on how much gas you take into the water with you, and how big you are. When I dive a 130, I'm going to be about eight pounds negative at the beginning of a dive, to allow neutral at the end with 500 psi in the tank. My lungs can't compensate for 8 lbs negative, so extra gas has to go into SOMETHING to compensate. There's no shame in it AT ALL; that's WHY we use buoyancy compensators. As far as I'm concerned, I'd much rather see somebody using his suit or BC competently, than dive with someone who's overusing his lungs for buoyancy and retaining CO2 (or burning through his gas) as a result.

Similarly, there is no extreme virtue to "hot drops" (going in with everything empty). If you dive into very heavy current or where surface conditions are unpleasant or risky (high boat traffic, for example) it can be advisable to get underwater quickly. But when you jump off a boat in Puget Sound, it's frequently JUST FINE to spend a couple of minutes at the surface, gathering your team, reconfirming everything's functioning, and doing bubble checks. Different diving circumstances make different procedures optimal.

Thal's trick with the inflator works great in a wetsuit, where the BC is the only expanding gas site. Not quite so well in a DS, unless you are lucky enough to be able to position your DS exhaust valve precisely enough to allow it to do the same thing.

Rear dump or inflator hose is one of those arguments that rages, and I've failed to be compelled by either side of it. The key is to look at where you are and what you are doing, and adjust which you use to make it easiest and safest. If you are close to a silty bottom, you don't want to break trim to use the inflator hose. If you are in midwater, a brief rotation out of trim can allow you to dump wing and DS simultaneously, which to me is a good thing. Watching fellow students make like rocking chairs (butt up to dump wing, shoulder up to dump suit), I have never felt that was the ideal way to conduct an ascent.

But all of this is off the topic of the OP. I think he's gotten his answer here, which is that the vast majority of us do not see a pull dump as a significant advantage, but do see it as a failure point that could result in a very nasty reduction in function. As is always true in diving, he will have to make his own decisions about risk and benefit. I can only say that in my experience, it's very easy to say, "Oh, that's ridiculous, it will never happen to me," and then wish you had listened when it does

 

[Gombessa]

I was just looking over a friend's Coz dive gallery, and there were quite a few pictures of leaky shoulder OPVs with a constant stream of bubbles. Sure that could happen with the butt dump as well, but the potential failure of the valve (minor or otherwise) is a real possibility.

 

[HatchetJoe]

Unless I have to hang at the surface on entering off a boat I rarely add any air to my bladder to begin with. Therefore non means I don't havre to let any out. Sometimes I dive singles with various friends and in that case I have this new thing called a BC, It's a Seaquest Black Diamond and has 4 dumps, I actuall take a second and think about which one to use. Hey I'm underwater and it's all good. Learn to use your gear and you can get by no matter what it is. Focus on you brain and less on your gear, all the semantics just cause confusion, skill are what matter, personally I think all the toys are just bling.

 

[Scott M]

TS&M, As always the voice of reason. In the end it is up to each and every person to decide what will and will not work for them. I want to be the good little diver and make all the right gear choices to try not to duplicate efforts and certainly try to not build in a problem. Sometimes I have to throw some stuff up against the wall and listen to the responses it all helps me to decide.

For me with the dump valve, I am still seriously considering it. Mainly because my three dive buddies all use them and are used to them. I had the DS incident I spoke about a few posts ago. It was an uncontrolled ascent, it's a long story but in the end I am assuming from holding the inflator botton and the deflator botton at the same time with my DS gloves on. My buddy who always uses a shoulder dump tried to help me by dumping his air quickly with a little pull of his dump valve and then trying pull mine, not knowing I did not have one, had I had one the ascent could have been avoided. We went over a lot of the gear differecnes in our pre-dive meeting but I never thought about the dump valve. There was no harm no foul but I could have at that time when I was vertical just gave a little yank and dumped. With tnflator above my head I could not see I was pushing both at the same time. With a dump valve there is no risk of this ever happening. I'm sure I can get used to the standard method but it is still a little ways away from being ingrained into muscle memory.

Regards