Roll offs and routing LP hoses.... the assumptions

[Diver0001]

Here's a thought :

The rationale usually given for the choice of putting the inflator on the right post is that the left post can roll off and if it does you could lose buoyancy control if your inflator is on that post.

I'd like to question that assumption:

It would seem somehow equally logical to put the inflator on the left and the drysuit on the right because (a) in the event of a roll off you can still deal with the inflator manually, which you cannot with the drysuit (b) in the event of a roll-off that you didn't notice, it would show up more quickly if your inflator were on that post and (c) all things created equally it would give a slightly "cleaner" look to the hose routing.

In fact, I think this is one of those things that we do like we do it just because everyone else does it like that.

The question is this: Has anyone here ever actually HAD a roll-off that they didn't notice and would have caused a sudden and uncontrollable loss of buoyancy control (the assumption we usually accept as valid reasoning) if the inflator had been on the left post?

It would seem nearly unimaginable to me if you have the skills necessary to be in an overhead in the first place, that something like this could cause any kind of problem.

Anyone?

Ever?

R..

 

[rjack321]

Didn't happen to me, but I have seen a valve turnd off by a few feet of rubbing on a taut anchor line.

 

[Rainer]

There are better reasons to keep the wing inflation hose on the right post:

(1) In case of runaway wing inflation (which in cold water can cause the hose to freeze to the inflator; yes, I've seen it happen), now you just invert head down, fin to maintain depth, reach back with your left hand to dump the wing, and calmly shut down the right post. Switch to the secondary reg and sort yourself out. If you have the wing inflator on the left post, you can't shut it down while dumping and maintaining depth.

(2) Provides a second usable reg (via the inflator) in a donation scenario. While certainly unlikely to ever be used, at least it's a possibility. Having that "reg" and the short (22") secondary on the same post doesn't at least provide this remote potential benefit.

In any case, I usually run my DS from a dedicated bottle. I do now keep a spare DS hose on the left post. The "cleaner" look from not having to cross the hoses is pretty weak, especially in light of (1) [and I guess (2)] above.

 

[Diver0001]

There are better reasons to keep the wing inflation hose on the right post:

(1) In case of runaway wing inflation (which in cold water can cause the hose to freeze to the inflator; yes, I've seen it happen), now you just invert head down, fin to maintain depth, reach back with your left hand to dump the wing, and calmly shut down the right post. Switch to the secondary reg and sort yourself out. If you have the wing inflator on the left post, you can't shut it down while dumping and maintaining depth.

Hadn't considered the possibility that the hose could freeze to the inflator. I've had a number of freeflowing inflators over the years but I've never seen one freeze to the nipple. I could imagine it happening though.

(2) Provides a second usable reg (via the inflator) in a donation scenario. While certainly unlikely to ever be used, at least it's a possibility. Having that reg and the short (22") secondary on the same post doesn't at least provide this remote potential benefit.

Seems like reaching. I wonder if there has ever been a diver who found themselves in this position. I understand it theoretically though.

In any case, I usually run my DS from a dedicated bottle. I do now keep a spare DS hose on the left post. The "cleaner" look from not having to cross the hoses is pretty weak, especially in light of (1) [and I guess (2)] above.

Agreed. cleaner routing was reaching but I needed something to stir up the bee's nest....

R..

 

[Diver0001]

Incidentally, maybe this is a picky point, but you don't have to go to any convolutions to maintain depth if your inflator starts to freeflow like leaning down, finning and reaching for the butt valve. The inflator itself can dump as fast as it can fill. They're designed like that.

 

[Rainer]

I've only had to deal with this in a class (T1), where the instructor came from behind and just hammered the inflator and didn't let go. We hadn't discussed this before, but I assure you, by the time it occured to me what was happening, I had become slightly positive. I could have tried pulling the inflator hose off, but I'd be rising that entire time. I could have just sat there dumping, but that isn't going to stop the wing from inflating. The easiest solution I hit upon was the slightly head down angle, while dumping, and turning the valve so the wing would stop inflating. The head down bit was more to facilatate butt dumping than finning, but at least I was in a position already where I could arrest an ascent by finning down if needed.

After this was sorted, I checked my depth. I'd only risen a couple of feet. Seems easy enough, but I don't see it happening with the inflator hose on the left post.

For a slower leak, sure, many ways to skin the cat.

Incidentally, maybe this is a picky point, but you don't have to go to any convolutions to maintain depth if your inflator starts to freeflow like leaning down, finning and reaching for the butt valve. The inflator itself can dump as fast as it can fill. They're designed like that.

 

[DA Aquamaster]

The question is this: Has anyone here ever actually HAD a roll-off that they didn't notice and would have caused a sudden and uncontrollable loss of buoyancy control (the assumption we usually accept as valid reasoning) if the inflator had been on the left post?

No. I make it a habit to check for a roll off anytime I have any overhead contact in restrictions, etc. I do on occasion find the valve rolled off a half turn to a turn, which is enough of an incentive to reinforce maintianing the practice.

 

[jjones9527]

Incidentally, maybe this is a picky point, but you don't have to go to any convolutions to maintain depth if your inflator starts to freeflow like leaning down, finning and reaching for the butt valve. The inflator itself can dump as fast as it can fill. They're designed like that.

In practice it doesn't really work like that. By the time you notice you've already become slightly positive, and dumping with the inflator may prevent more gas from entering the wing, but doesn't really get enough out fast enough to prevent a run away ascent. Going head down and using the rear dump allows to to dump gas faster than it can go in, allows you to fin to maintain depth if required, and buys time while you shut the valve down.

 

[Diver0001]

In practice it doesn't really work like that.

In fact, in my experience it works exactly like that. I would agree that until you've had it happen a couple of times you might not recognise it right away but that's a training issue.

I don't want to insult anyone but if I can train my OW students to respond to me hammering the inflator when they don't expect it and deal with it by venting, exhaling and unclipping the hose then I'm sure that divers with 1000 times more experience shouldn't be taken by surprise by it.

I'm gathering that since you said the same thing that Rainer said that this is how you're taught to deal with it. If you want to do this, ok. I don't care. Whatever works works, right? I'm just saying it isn't necessary.

R..

 

[Cave Diver]

(1) In case of runaway wing inflation (which in cold water can cause the hose to freeze to the inflator; yes, I've seen it happen), now you just invert head down, fin to maintain depth, reach back with your left hand to dump the wing, and calmly shut down the right post. Switch to the secondary reg and sort yourself out. If you have the wing inflator on the left post, you can't shut it down while dumping and maintaining depth.

Not being a cold water diver, this is something I never gave any thought to. Good info though, because a stuck inflator isn't restricted to just freezing up.