First, UP has a wealth of knowledge. His comments are sometimes pointed, but he is usually right.
The comments about air in a tire relate to the fact that Nitrox and/or trimix are more suitable gasses for diving than air.
Second, I think that the next size up from a 13 is a 19. Its too d*** small for safe ascents, IMHO. I tested one as follows. I went to the pony, returned to the line, fouled the hook and ascended at a safe rate while making safety stops. I ran out before I hit the surface.
Moreover, that test was done at a normal breathing rate. I suspect that if I had actually needed the pony, my rate would have gone through the roof and I would have run out earlier.
Those small bottles DO belong on a store shelf, IMHO, since they most probably won't perform their intended function of getting you to the surface.
I understand that pony's are an intermediate step between nothing and a full set of doubles. They have their place as it is somewhat disingenuous to tell someone to buy doubles. However, the size your proposing is a pacifier. It is comforting, but does nothing. In fact, it may be more dangerous than nothing if you try to rely upon it.
My sizing recommendation stands.
P.S. Why are you using a combination power inflator/octopus. Have you tried ascending from depth with it?
P.P.S. Consider your mounting choice. You have created an entanglement hazard. Sling mounting the bottle and using elastic fabric to hold the reg hose frees your arm, streamlines you and makes it possible to move/drop/replace the bottle if necessary.
Just my 0.02
The comments about air in a tire relate to the fact that Nitrox and/or trimix are more suitable gasses for diving than air.
Second, I think that the next size up from a 13 is a 19. Its too d*** small for safe ascents, IMHO. I tested one as follows. I went to the pony, returned to the line, fouled the hook and ascended at a safe rate while making safety stops. I ran out before I hit the surface.
Moreover, that test was done at a normal breathing rate. I suspect that if I had actually needed the pony, my rate would have gone through the roof and I would have run out earlier.
Those small bottles DO belong on a store shelf, IMHO, since they most probably won't perform their intended function of getting you to the surface.
I understand that pony's are an intermediate step between nothing and a full set of doubles. They have their place as it is somewhat disingenuous to tell someone to buy doubles. However, the size your proposing is a pacifier. It is comforting, but does nothing. In fact, it may be more dangerous than nothing if you try to rely upon it.
My sizing recommendation stands.
P.S. Why are you using a combination power inflator/octopus. Have you tried ascending from depth with it?
P.P.S. Consider your mounting choice. You have created an entanglement hazard. Sling mounting the bottle and using elastic fabric to hold the reg hose frees your arm, streamlines you and makes it possible to move/drop/replace the bottle if necessary.
Just my 0.02
... why someone would say the air in a pony bottle belongs in tires or a pony bottle belongs in a store window.
