Carrying a Pony....

[M_Bipartitus]

Since motorcitydiver is in Michigan, and I hope he takes advantage of the local wrecks (as I hope to soon.) If diving near or in wrecks it should be better (IMHO) to sling, as the sling is more streamlined and less likely to get snagged on a wreck or nearby fishing lines. Also if it does get snagged on something it is easier to get off, or to cut free if it's on the side/ front of the diver.

Matt

 

[The Kraken]

Sorry for the Hi-Jack, guys, but . . .

Merry Christmas, M Bipartitus !!!!

We miss ya !!!!

The Kraken and Yellow Angel Fish

 

[in_cavediver]

Fundementally we agree. To compare, let me rephrase the cases. (mind you, for me, its always case 2 iregardless of tank size)

Case 1, independent doubles of disimilar tank size - IE, 80 + 19, 30 or 40
- This case is exactly as you describe. Incorporate tank into gas plan and you
can dive them like independent doubles. 2 1sts, 2 2nds, just like doubles. You
argue whether the 19 is big enough but it really a personal choice and
dependent on the dive.

Case 2 - small pony tank (6, 13 and 19)
- This is the case I spoke of. This is when you are looking to maintain you're
personal redundant gas. I would advocate excluding it from the gas plan and
based on the size (6-13), be cautious of wanting this as my primary octo
supply for my buddy. Remember, we are now carrying the pony because we
don't trust our buddy to be there and don't want to CESA. Depending on the
dive, we may or may not consider the 19 big enough. (personal choice).

Your last point about the double failure is moot. 2 normal rec divers can't survive the double failure scenario without either a CESA or another divers. The idea of 2 2nds on a pony tells me to look at other gear options. If you need that, you really need a different gear set. (either 2 pony's, doubles etc)

I began slinging my pony when it became diffucult to reach it back mounted. I do not agree about not including the pony in the "gas plan." That is why it is being carried, it represents your emergency backup and if buddy diving it also likely represents his as well. Pony bottles are mostly used with singles and that is what I am talking about. The typical single tank is 70 to 85 cf. A 20 cf pony represents 20% of that volume and a 30 represents 30% of that volume. How much "gas" do you think is going to be left in an aluminum 80 after a 90 foot dive (30 minutes at 90 feet is no deco per Navy Tables). Well, for me, quite a bit, more than enough for a generous safety stop but not enough for a buddy. I am going to probably leave bottom at 1200 psi, surface at 300 psi. That is not enough for a buddy and the donor diver. Now let's look at this, 1,000 psi on an aluminum 80 represents 26 cf. The numbers indicate that a 19/20 cf (that is approximately what I am off bottom with to begin with assuming a normal and no failure dive) bottle should get a buddy out of trouble or yourself and that a 30 cf bottle would be plenty. Within no deco limits down to 100 feet the 19 cf bottle should be plenty to return a buddy to the surface or yourself. From 130 feet the 30 will do nicely. Now, ok, double failure, your buddy has a system failure and goes to your pony. You also have a failure--oops--the pony does not have an octapus so now the two of you buddy breath from the pony, on a 30 cf bottle from 90ish feet the 15 cf each will get you to the surface but not much more. A 40 would do it cleanly. So there are the things that go into selecting the size pony for your single tank dive. yeah, if your on doubles then you don't generally need the pony. That is why I have my Double 50s set up with dual regulators. I dive the Double 50s as if they were a SINGLE 80 cf tank. That leaves 20 cf over for emergency--exactly the same as an 80 cf single with a 20 cf pony. Doubles are great but you cannot rent doubles at vacation resorts, they are rarely available even in Florida or California for rent, you can carry travel bands and build them up or set then up as doubled singles but then you realize of course that your single BC is not going to work for that so you have to carry two sets of gear for diving singles and doubles---that is a lot of carry on.

There was a thread a few weeks ago about having an octapus on your primary rig and a pony and it was pretty much 50/50, some do not have a octapus if they dive a pony, some do because they don't want to have to set up the regulator different for every dive(it occurs to me that not everybody has about 20 different dive sets--lol). For me, if I am on a single 80 cf tank and I carry the pony then it will not have an octapus and the octapus is the pony regulator. This represents a much higher level of redundancy than a single 80 with a single first stage and two seconds. The pony obviously provides an independent air source with a complete regulator of it's own. With the pony side slung it is quickly available, a 40 inch hose gives the pony second stage plenty of room to manuver. It is important to remember that a conventional octapus is for air sharing only, it is not true redundancy. Carrying an octapus is not a bad thing with a pony, just probably not needed but I don't see a problem with it and in fact do so from time to time--but consider the typical isolation manifold doubles. Typical doubles have two independent regulators, neither would typically have an octapus second stage so you have two complete regulators. Well, that is exactly what you have with a single and a pony, two complete regulators so why carry an octapus any more so than with doubles? I don't really recall ever seeing doubles with twin regulators and an octapus on either or both but --well--once I did, he also had two computers and three consoles and I sort of lost count and this was in Alexander Springs which is at most 30 feet deep. I was on a single 72 and Pico Mistral, I wanted to talk to him but he got in after me and got out before me--go figure.

Merry Christmas.
N

 

[Flea Dog]

Back to carrying/mounting a pony bottle.

I have used to Reef Scuba pony bracket. It fits a 19 cu ft pony very nicely. Very easy to change as lng as you can rethread your BC strap correctly. I spoke to Reef scuba about using two with a 30 cu ft pony, they said it would be fine. Only problem is the reg on my 30 is even with my tank reg, (same height.) This gets a little tight to work the valves etc., so I sling the the thirty.

Leisurepro has about the best price on it.

http://www.leisurepro.com/Prod/RSAX...l&AdvSrchSortField=Relevance&SortDesc=0&Hit=1

 

[Nemrod]

"Your last point about the double failure is moot. 2 normal rec divers can't survive the double failure scenario without either a CESA or another divers. The idea of 2 2nds on a pony tells me to look at other gear options. "


I don't know, if one of the divers had a pony and his buddy had a failure and he went to the diver with the pony and then in some strange twist of fate the donor diver had a failure then they could get to the surface on the pony--maybe--by buddy breathing the pony--since unlike the typical singles rig (no pony) a double failure would result in a forced ascent (what you call a CESA). Therefore, the pony does provide a extra level of redundancy for a singles buddy team, if you can buddy breath--AND--the point I did not make before was that it is my thinking that may be easier to do if the pony were side slung with a 40 inch hose (or a standard hose). If it were back mounted it would still be possible of course to buddy breath the pony I suppose but somehting just makes me think it easier if it up front. The other advantage would be having either a button spg or a standard spg on a short hose on the pony, perhaps quite useful on larger pony bottles. I am using the Mark V type first stage which is a turrent style piston first stage and very reliable, at least in the 25 years I have been using them. The turrent allows easy routing of the hose from stowed to deployed when the pony is slung.

Actually, I have nothing against back mounted, I used to do it that way. My bracket was homemade. It uses two large nylon tie-straps that secure a aluminum tray to the main tank. This tray looks something like a single pice STA. The tray then has two adjustable clamps with thumb screws that secure the pony to the tray. In my last use of it I switched to circle clamps on the main and nylon straps on the pony to the adapter. I bent the tray from 0.60 aluminum as I recall. I later made another on the same principle but it had a slot in the center that I would thread the cam band through thus locking it to the tank. This did not work as well because the single point attachment via cam band would allow the pony to rotate somewhat. If I were to make another today it would be designed to work with the double cam band back plate. It would be open slotted on both ends so that loosening the double cam bands of the back plate would allow the pony bracket to be slipped into place. The pony would still attach to the adapter via stainlesss steel circle clamps (large hose clamps). The tray I am describing is like a Vee but with two bends rather than a single bend so that the Vee is flat--has a foot--of about one inch. BTW, I saw a PVC device very similar to what I am describing, also homemade. It looked to be made from PVC four or six inch pipe (?), cut in half and then partially flattened probably by heating. It was a gray PVC. Anyways, no need to spend major money on simple pony brackets. If I get a chance I may dig through my piles and piles of gear and see if I can dig it up.

The one I did picture, the slung bottle, was made using instructions from DocIntrepid I think so I credit him with it, he had a link to someplace I have long lost.

Another odd rig I once saw being used was the Hawaiin Harness with the pony attached to the LH frame of the rig again using circle clamps around the pony and the frame--no adapter needed.

Now here is something, see the pic below and disregard everything but the yellow hose thing. That is a SeaTurtle second stage regulator--just a simple tilt valve in a small mouthpiece you bite on to breath. I am thinking to get rid of the conventional second on my pony for solo diving and use the SeaTurtle straight to a Mark V. Simple, streamlined and reliable but may need an OPV in that set up.

Edited--I just clicked on the link from the laughing guy and see that it is similar to what I used to make except that it has a curved foot against the main tank which would allow it to be stable with but a single attach point, clever, at 40 dollars, well, if you have no access to tools, fire and axes then perhaps it is the way to go.
N

 

[GeorgeC]

This one detail though is significant. I advocate the (3) 2nds, with (1) stowed on the pony stage style to completely isolate the pony from the main gas supply and emergency procedures. Using the octo as the pony 2nd incorporates the pony into you gas plan as this is now your buddy's reserve to end the dive. Not a good idea is its a 6cft or 13cft pony. On a 40cf bottle, its not a major issue.

The way to look at is this, with one 1st and 2nd on each bottle, you have one access means for one diver on each bottle. Sometimes its better (especially with smaller pony tanks) to keep the backgas accessible by two divers at the same time.

I follow your point and agree. However, I dive a 30cft pony and all of the other divers who dive singles also dive a 20cft or greater pony. This is a mandatory boat policy. Between my buddy and me we have 4 regs connected to 4 separate gas sources. I don't think 6 regs are necessary in this config.

 

[GeorgeC]

Please delete double post

 

[MB104]

I have a 19 cf pony that I use when diving a single tank. I use the "Pony Tamer" to attach it to the side of my tank, which has been very good to me. I offset the weight with a trim weight on the other side, either on my backplate or in the BC using a zip tie. The bracket is attached by using metal bands. The bracket has a "male" or "female" which go together. A pin is used to secure it together. I have been using this method for several years, but now that I've doubled my tanks it is a moot point. If you want to attach a pony, this is a consideration. You may want to consider a larger pony, like a 30, since a 19 has its limitations.

 

[shadragon]

Found this simple rig when I was looking for a mount for my 40 cf.

http://www.oceanscan.com/underwater/scuba.htm

Simple and fits all sizes of tank. Fast changeovers and stays put, so no shifting center of gravity. Seeing as this is my emergency air source I have no desire to hand it off and am quite happy to have it secured against my main tank as I dive singles. Was about $40 CDN for the kit.

 

[in_cavediver]

I follow your point and agree. However, I dive a 30cft pony and all of the other divers who dive singles also dive a 20cft or greater pony. This is a mandatory boat policy. Between my buddy and me we have 4 regs connected to 4 separate gas sources. I don't think 6 regs are necessary in this config.

I agree with your assessment. In your specific case, there isn't a great reason to have another alternate as you can all dive as different tank size independent doubles. (and everyone has this config which is important)