7' Hose Questions (not routing)

Here’s what I don’t get about 7’ hoses in confined spaces like a submarine.

1. Say your buddy is 6’ tall and fins add 18"-24". Assuming your buddy exits first, how do you keep from getting kicked in the face all the way down the passageway?

2. I have seen people diving with a 7’ hoses, but there is no strain relief. Let’s say things turn to crap and your sharing buddy gets pulled away. The entire strain is on that brass 3/8" fitting and your first stage. Shouldn’t there be a strain relief on a long hose so it doesn't break the fitting? Hoses are pretty strong in tensile but the fitting is not when pressure is applied at an angle.

3. A lot of divers wrap the excess hose around their neck. From the standpoint of deploying and entanglement wouldn’t it be better to figure-8 between the cylinder and wing with tear-away expendable pieces of bungee or bicycle tubing?

My submarine penetration dives pre-date the evolution of technical diving. We rigged a 150' x 3/8" umbilical to gas banks made from sets of doubles left outside with a tender/standby diver. We both wore low-profile bailout bottles that were never normally used. The diver would enter solo with the tender outside also breathing off the external cylinders. We considered two people inside the same compartment a much greater safety risk. We even rigged diver-diver hardwire coms on one project, which worked really well with British-made Normalair masks.

Akimbo, I think folks assume that the leading diver will adopt the frog kick technique with the knees bent 90 degrees and mainly using ankles for propulsion which would then place the fins above the following diver or adopt same swimming position but only use hands to pull you forward instead of using fin to propulse you. I would think that in a submarine, there would be plenty of things to grab to facilitate the pulling method.

More traditional vs Figure 8 ... the excess hose is normally routed downward and very tight against between the wing and the plate to the buddy, under the battery compartment of the can light and then across the front and around the neck. I think people do feel that if it snagged, it will be in front of you where it will become easier to unsnag rather than somewhere on your side or perhaps behind you.

Akimbo:

Here’s what I don’t get about 7’ hoses in confined spaces like a submarine.

1. Say your buddy is 6’ tall and fins add 18"-24". Assuming your buddy exits first, how do you keep from getting kicked in the face all the way down the passageway?

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Practice

2. I have seen people diving with a 7’ hoses, but there is no strain relief. Let’s say things turn to crap and your sharing buddy gets pulled away. The entire strain is on that brass 3/8" fitting and your first stage. Shouldn’t there be a strain relief on a long hose so it doesn't break the fitting? Hoses are pretty strong in tensile but the fitting is not when pressure is applied at an angle.

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It will take a whole lot less strain to pull a reg out of the recipients mouth than it will to pull the fitting off, unless it already has a problem. They're not going to have that much strain on it. The recipient leads out, and his is not gonna swim faster than his gas supply can keep up.

3. A lot of divers wrap the excess hose around their neck. From the standpoint of deploying and entanglement wouldn’t it be better to figure-8 between the cylinder and wing with tear-away expendable pieces of bungee or bicycle tubing?

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Possibly. But if it comes loose, or you have to share air temporarily, or do a drill, how are you going to restow it? The "neck wrap" works remarkably well, presents very little entanglement issue and is easy to clear and restow if needed. I know people who prefer a "long hose stuff" method. I tried it and found it clumsy and difficult.

My submarine penetration dives pre-date the evolution of technical diving. We rigged a 150' x 3/8" umbilical to gas banks made from sets of doubles left outside with a tender/standby diver. We both wore low-profile bailout bottles that were never normally used. The diver would enter solo with the tender outside also breathing off the external cylinders. We considered two people inside the same compartment a much greater safety risk. We even rigged diver-diver hardwire coms on one project, which worked really well with British-made Normalair masks.

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Decisions on soloing or entering cramped quarters together is a personal decision. I've done it both ways (not in a sub). You've got to decide what works for you.

Akimbo:

Here’s what I don’t get about 7’ hoses in confined spaces like a submarine.

1. Say your buddy is 6’ tall and fins add 18"-24". Assuming your buddy exits first, how do you keep from getting kicked in the face all the way down the passageway? .....//.........

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Basic Cave Diving -a blueprint for survival. 5th edition. 1986. Page 38. If you find something better, I want to know about it.


IMHO, Exley was way ahead of his time.

Cave Diver:

Practice ...

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Why not just get a longer hose if that is all you are depending on? What if you rigged it so the loops of extra hose pulled successively; say 2' at a time? Then would in matter if the hose was longer? In the event of an air sharing emergency that occurred in unconfined conditions, you wouldn’t have to deal with as big a loop of loose hose.

Cave divers may practice this sort of thing but I can’t see wreck divers spending much time at it under real conditions.

Cave Diver:

…It will take a whole lot less strain to pull a reg out of the recipients mouth than it will to pull the fitting off, unless it already has a problem. They're not going to have that much strain on it. The recipient leads out, and his is not gonna swim faster than his gas supply can keep up...

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I was thinking more of open sea conditions than caves — high current and the trailing diver getting hung up as the lead diver was heading for the hatch or up the anchor line. It is difficult for me to imagine that the lead diver won’t be holding on to the hose in a real emergency to prevent getting the second stage from getting yanked out of their mouth… which could be bad situation itself.

Given that most hoses come off the first stage at a right angle to the direction of strain in this case, the fitting would be quite vulnerable. It would not be hard to tie-off a strain relief to the cylinders.

Cave Diver:

… Possibly. But if it comes loose, or you have to share air temporarily, or do a drill, how are you going to restow it? ...

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Interesting point, practice drills are a factor I had not considered. I am not too concerned about accidental deployment since you can rig it to require a substantial pull to release. I suppose you could wrap it around your neck or stuff in your harness for a quick and dirty fix on accidental deployment. It sure seems like all that hose could become a rat’s nest when you go on your backup regulator in adverse conditions.

Thanks for the insight.

lowviz:

…If you find something better, I want to know about it...

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Trying to understand all the factors the lead to the 7' hose and discussing sort-comings is one means of determining “something better”.

Which Subs..... Seen a couple Uboats off NC's coast.

Akimbo:

Trying to understand all the factors the lead to the 7' hose and discussing sort-comings is one means of determining “something better”.

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If it wasn't for the word "copyright" I'd just scan and post the answer. Buy the booklet, It's about 8 bux for a cheap reprint, I shelled out way too much for an original copy. However, I consider it to be well worth what I paid.

Akimbo:

Why not just get a longer hose if that is all you are depending on? What if you rigged it so the loops of extra hose pulled successively; say 2' at a time? Then would in matter if the hose was longer? In the event of an air sharing emergency that occurred in unconfined conditions, you wouldn’t have to deal with as big a loop of loose hose.

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Logistics for one thing. Some people have tried 9' hoses. It doesn't stow as well, doesn't add significant length to get you out of the way of full frog kicks to make it worth the extra effort. If your passage is too tight to go side by side, you're probably using a modified frog kick anyway, so you're not *that* close to getting kicked by your buddy, and if you do (at least if we do) we are cognizant of the fact that our buddy is in close proximity and take some of the power out of the kick. Worse case scenario, following diver will grab the lead diver shin and push them forward by providing the propulsion for the team.

Cave divers may practice this sort of thing but I can’t see wreck divers spending much time at it under real conditions.

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How real do you need it to be? Single file in open water can work just fine for practice. You don't need to be in confined conditions to work out the issues.

I was thinking more of open sea conditions than caves — high current and the trailing diver getting hung up as the lead diver was heading for the hatch or up the anchor line. It is difficult for me to imagine that the lead diver won’t be holding on to the hose in a real emergency to prevent getting the second stage from getting yanked out of their mouth… which could be bad situation itself.

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In an open seas condition you won't be lead/follow position. Side by side swimming or face to face during ascent works just fine. The only reason for single file is navigating restrictions that dont allow side by side.

Given that most hoses come off the first stage at a right angle to the direction of strain in this case, the fitting would be quite vulnerable. It would not be hard to tie-off a strain relief to the cylinders.

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Mine don't. Proper hose routing is part of configuring gear properly. If you feel better adding a strain relief, it's your gear so do as you wish. I just don't see it as big enough an issue to matter. My fittings are protected enough that I'm not worried about hitting them and shearing it off and I just dont see enough strain being put on it from an air share to cause a problem.

Interesting point, practice drills are a factor I had not considered. I am not too concerned about accidental deployment since you can rig it to require a substantial pull to release. I suppose you could wrap it around your neck or stuff in your harness for a quick and dirty fix on accidental deployment. It sure seems like all that hose could become a rat’s nest when you go on your backup regulator in adverse conditions.

Thanks for the insight.

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S-drills are an important part of the pre-dive procedure to make sure the hose is routed properly and not caught on something. An air share emergency is not the time to figure out that the hose is hung up or routed improperly and won't deploy. That's one of the beautiful things about wrapping the hose, it deploys and stows easily.

lowviz:

Basic Cave Diving -a blueprint for survival. 5th edition. 1986. Page 38. If you find something better, I want to know about it.


IMHO, Exley was way ahead of his time.

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The picture depicted there with the lead diver swimming slightly below the second diver works on the assumption that the passage is sufficiently high to allow that position. That's not the only position possible for a single file exit.