Scenario;
Cave has four sumps, first two will be done with 300bar 7's and the second two with 232bar 7's. Tanks will be side mounted.

Question;
What is the best way of carrying the 232 7's through the first two sumps?

Had a dive through Peak Cavern Resurgance on Saturday with them mounted like this;





Anyone got any better ideas?

Johnny I'd recommend that you lose the snap gates as they're just waiting to catch line.

The Badger said:

Johnny I'd recommend that you lose the snap gates as they're just waiting to catch line.

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Cheers Badger
Which ones?
I used two clips for the rear cyliders (instead of one) to get them lower so that they did not get in the way of my arms, I will replace the top one with a screwgate as that one can stay on my harness. To get rid of that one I would have to extent the loop from the cylinder but that would make it sit too low when I use it as my primary tank.

I would have to say that the two snap gates at the bottom *do* look nicely sited to catch line. Is there are reason (bar cost) that they cant both be replaced with screw gates (or one mallion attached to clip on harness one screwgate on bottle.

Spoke to johnny today on the phone about this. We argued the toss - and the being able to dump the bottles quickly came out as a clear winner. but a good point about flipping the crab.

Ive had enough trouble with stuck screwgates on the nice clean gritstone edges of the peak district - let a alone down muddy cold caves so Im hearing you on that one.

Er, bit confused here. The reply that I posted bears no resemblance to what is written above. These are not my words at all! What's going on here? Is someone editing what's written without the author's consent?

Errm :? :? :?

I wrote that - Im sure I didn't edit your post - just did a quote. - Maybe I did hit the edit button by mistake - Sorry if that was the case - as you made some very valid points.

Joel - I read your reply soon after you posted it; it was several paragraphs long and made some very good points. It was definitely there on the diving section. Having just checked it now "your" posting is totally different (and far shorter). It would be useful to get to the bottom of this problem.

Joel - any chance of recreating your post ?

Years ago I did several dives in Joint Hole using four cylinders. I used a chest harness and waist band made of shock-cord. I found this system very good, it was easy to put bottles in and out and they never fell off. It also gives good weight distribution. I also found that all four cyclinders had their "individual place" - I never had any trouble mixing up guages or regulators.

A particular weakness of your idea is that you can't conveniently drop one stage cylinder, continuing on three /you could, but you would be very unbalanced). That might not be appropriate if the two pairs of tanks have different gas mixtures, but of they all contain air, it's useful to be bale to dump one of the tanks

How to make such a chest harness....


Take a length of 8-10mm shock cord. Tie a smallish loop with an overhand knot in the middle. Put this in the middle of your chest. Take the ends around your body to the small of your back and tie a second overhand knot, just in-line (no loop). Now take one end over each shoulder. (For each end now do the following, I've only described it for one) Tie a simple overhand knot, loop the end over the part running over your chest and back into the overhand knot.

(The waist loop is just a simple loop of shock cord which you wear around your waist.)

At this point you should have a sort of bizarre "bra". The loop you tied at the very beginning is the "handle". You can grab hold of it and pull the chest loop out, and hook it over the pillar valve of one or more tanks. The reason why the shoulder loops are not firmly tied but looped over the chest loop is so that the chest loop can expand to the size of the load. The bottom end of the tanks go in the waist band.

John Cordingley showed me this system. I don't know whether he invented it himself, but it worked great for me. I even caved between sumps on occasion with a third cylinder in position on my chest and it still never fell off.

I realise that a picture would be worth any amount of words trying to describe this solution!

Mark

It was I who wrote the "spoke to johnny" post above after pressing what I thought was the quote button, I did then change my mind - and delete what I thought was the quote bit.. It turns out - it must have been the edit button I hit by mistake, and I deleted joels post - just leaving my comments.

Many apologies Joel.



I'll have a word with bubba to see if he has some sort of archive of it.

If not - do you want to post up the general gist - as you did indeed make some very valid and well thought out points.

Sorry again.

MSD - you're right, it was JNC who invented this shock sord system for use when diving side mounted on the main tanks (after seeing a shock cord system in use with back mounted tanks in France in the early 90s). There is a detailed description of it and diagrams in CDG Newsletter 127 (April 1998) pages 3 - 5. Any CDG member should be able to access this via the password protected area of the CDG website.

This system has been used extensively by side mounted British cave divers since the early 1990s and works well in most situations. However your system (in the pictures) might be better if you're intending caving between sumps. The shock cord method can be used to carry big heavy tanks but only in the water! Taking tanks on and off underwater is dead easy.

Haven't got anything useful to say about mounting your cylinders John but the diving kit and Ben Moon muscle vest is an original but effective look for the summer party season in Castleton.

Well I reckon it's most important to be comfortable under water. The chest elastic system obviously isn't totally secure abover water (but you'd be surprised what you can do without the tanks falling out!), but you can always secure them in a better way between sumps.

If there is a sigificant amount of caving to be done, caving with four tanks on is a bit of a non-starter anyway. Better to shuttle them through 2 at a time.

Another option is to have other combinations. That depends on the length of the sumps and whether all the tanks have the same mixture (or at least can be used as back-up, for example you can't count on a deep mixture for backup if the oxygen content is too low for shallow diving). For example, if the first sump is long, chest mount a 12 and continue on 2 7s and a third side-mounted smaller cylinder (which you use for sump 2). That way you dump as much of the load as soon as possible without having to carry it between sumps.

Obviously you also need to calculate your thirds margins carefully when playing this kind of game. I have dived on 2 4 litre tanks and a 12 on the chest before now. That's a bit extreme, although you can still manage to be within "thirds" provided you calculate carefully what your "dump" and turn-around points should be.

Mark

Now then Pitlamp - do you know JNC? He used to supply tea to the needy in Castleton - a very useful bloke to know!

Dan.

Oohh, have you splashed out on one of thoes fancy Dragon harneses Johnny?

Enjoy the trip you lucky thing!

danthecavingman said:

Now then Pitlamp - do you know JNC? He used to supply tea to the needy in Castleton - a very useful bloke to know!

Dan.

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Simon said:

Oohh, have you splashed out on one of thoes fancy Dragon harneses Johnny?

Enjoy the trip you lucky thing!

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JB said:

Haven't got anything useful to say about mounting your cylinders John but the diving kit and Ben Moon muscle vest is an original but effective look for the summer party season in Castleton.

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Aye. He still does it youth. Where's that picture taken of you leaning against the wall of that big rift passage?