Single tank Sidemount with HP100... weighting on the opposite side?

I'm used to diving with double Steel HP100's sidemount, however this weekend I'm diving a place where it makes more sense to do Single Tank sidemount. Anyone know how much weight will be needed on my right side to counterbalance the Steel 100 on my left? I also will probably take my AL40 for backup and sidemount it on my right.
I'm guessing 5 or 6 lbs.
I realize the balance will shift some between full and empty, but hopefully the Steel 100 won't be as bad as an Aluminum.
thanks- E.

A steel HP100 is somewhere around -3.5 empty to -8.5 full. An AL40 is around -1 full. If its for redundancy and it stays full, then you are probably right at around 5 pounds. That will put you in the middle of the buoyancy swing of the hp100. If you are going to breath off of the 40, you may need another pound or two.

Also, the lever arm from the tank to where you put the weight might be different. If the weight is closer to your body than where the tanks sit, you might be able to take off a pound or so.

Actually, an HP100 will be about .5 to 7lbs negative empty and 8.5 to 15lbs negative full (depends on the brand). The most common are in the 1lb to 8.5lb range.

Questions for the OP -

Have you ever done a single cylinder sidemount dive before?
Where are you diving that this would make more sense?
Why does it make more sense?

lulz

ucfdiver:

lulz
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You always have the coolest pictures...

Having recently "tested" a single HP100 dive in sidemount, it's doable ... but it's also effort. Unless there's a really compelling reason, I'd not choose to do it that way.

And if you're planning to sling a 40 on the right side anyway, why not just take the second 100 and leave the 40 home? I am having a hard time seeing what diving a 100 on one side and a 40 on the other side gains you ...

... Bob (Grateful Diver)

At the risk of being obvious,why not just put it on your back?

As acold saltwater,primarily open water diver with back problems who is considering sidemounting as a way to ease out of twin backmounted 100 hp's and who had thought perhaps out of backmounting to ease up the pain, I also recently asked almost the same question in a separate thread.
I have not yet heard and cannot at this time see any reason to sidemount a single cylinder.I can however see a few reasons why when looking at planned gas use in the 70-75 minus cubic foot range depending on the cylinder and its pressure to allow adequate redundancy of gas that anyone adverse to carrying extra tanks for no more reason than balancing themselves and or adding more ballast weight in the case of using alu 80's , not to mention most times using an alu 40 I have a richer mix than my back gas aboard. (I have considered sidemounting a couple of these alu 40's for shorter dives but find 80 cu feet limiting when compared to a pumped up lp95.I can see maybe using lp 72's although I do not own any.)

While I had hoped to free myself from my backplate and wing.I see that one must use different systems in different situations where each system's merits and strength's are best for the individual and or team.
Regretfully, i will stick with a back mounted Faber lp 95 and 40 cu ft for now and whenever i find a suitable sidemount BCD and the time to train myself to competency for either broken up 100 hp's twins or paired lp 95s and a deco bottle or 2 i will consider throwing cash at that specific task for sidemounting.

Estaff. Here are three ways to deal with your situation that have absolutely nothing to do with sidemounting a single cylinder as it sounds like a PITA to me although I have never done it with anything larger than an alu 40 for inspecting a vessels hull.
Stick the 100 hp back on a backplate and wing and sling your 40 when diving this dive plan , take both 100 hp's and carry a pile more stuff for no reason at all beyond trim or add to your personal tank farm to get yourself a couple smaller matched tanks for these occasions is what i hear.

Bill