drysuit inversion in sidemount?

[tbone1004]

have you ever dove twinsets?

This question is very easy to answer. Sidemount tends to naturally push your CoG down, same with most rebreathers, so floaty feet are a non issue, backmount has the manifold up on your head so it is trying to push you face down. It is that simple, nothing to do with hanging below rigs, or being easy to align your back/thighs. Doubles want to push you nose down into the dirt, and sidemount tends to want to push your feet down. Don't believe it? Ask why a lot of sidemount rigs have trim weights on the shoulders for wetsuit diving and guys in twinsets are putting on heavier fins and use tail weights.... It's all about center of gravity and on sidemount it is around your hips vs twins that are up at your shoulders

 

[Razorista]

'balanced rig' is not a sidemount innovation tbone

 

[tbone1004]

you don't get it, this has absolutely nothing to do with being in a balanced rig or not because most divers in doubles will never be in a balanced rig, same with most sidemount divers because of the amount of gas we are carrying in warm water. The weights in discussion have nothing to do with buoyancy, they are only there for trim.

The natural tendency of twin sets are to push you head down. This is because the first stages are up higher on the body, and you have a 2lb manifold sitting at or above your collar bone pushing you down. When you are diving in a drysuit, any air in the feet will have a tendency to push your center of gravity even farther forward causing you to go head down. This is countered by wearing heavy fins like the Scubapro Jet Fins that are the gold standard, wearing ankle weights or gaiters, and using tail weights to help bring the center of gravity down..

Natural tendency of sidemount removes the manifold, lowers the first stages considerably, and on most rigs attaches the lower attachment point below the waist. This causes you to go head up. To counter this in sidemount, we remove the heavy fins in favor of neutral fins like the OMS Slipstreams, Dive Rite XT's or a slew of other recreational fins you would never see guys in twinsets using, this helps to bring the CoG farther up, and in wetsuits, it is not uncommon to put trim weights on the shoulders to help bring the balance point up to the middle of the diver. In a drysuit, you don't have to have the trim weights because instead of using negative buoyancy up top to bring the diver to a flat trim position, you use positive buoyancy at the bottom. Same net effect of bringing the center of gravity towards the middle to facilitate flat trim.

 

[Razorista]

I do get it and mostly agree, but not completely.

You are turning a config specific factor into a general fact.
There are the flat bottomed tanks for example that give the twinset more weight at the bottom than at the top.

There are also a lot of divers who are not using heavy fins or ankle weights with a twinset.

And what about single tank backmount configs without any manifold or independent doubles?
Or upside down configurations.
Do those also offer sidemount equivalent flexiblity with drysuit problems?

 

[tbone1004]

the flat bottom tanks in twinsets help to balance but are not available in the US market and since that is where the OP is from, are not relevant to the discussion. These are advantageous for twinset diving obviously and detrimental in sidemount.

Most divers do not use ankle weights, however the Scubapro Jetfins are the standard and are considered heavy fins. Very uncommon to see neutral or floaty fins used with technical diving twinsets

Single tank backmount has a significant amount of weight distributed above the hips due to the steel backplate, however if using a stab jacket and a boat load of lead, you will tend to be feet heavy, though this is in the technical diving subforum so twinsets are what it is being compared to. Single tank sidemount with a single AL80 or even twin tank sidemount with al80's are not nearly as prone to being foot heavy as steel tank sidemount setups.

Inverted doubles are not common enough to warrant discussion, though tend to behave more similar to sidemount in terms of trim

 

[Razorista]

the flat bottom tanks in twinsets help to balance but are not available in the US market and since that is where the OP is from, are not relevant to the discussion. These are advantageous for twinset diving obviously and detrimental in sidemount.

Weigths between the tanks are there to have the whole set trimmed, aren't they? Even without the diver attached.

Most divers do not use ankle weights, however the Scubapro Jetfins are the standard and are considered heavy fins. Very uncommon to see neutral or floaty fins used with technical diving twinsets

I do not feel much of a difference and the numbers support that - the steel heel strap is the heaviest part of the rubber fins when submerged and most 'normal' fins have those as an extra too.
They give a nice cozy feeling of having done something about the floaty feet, but I do not see how they could help otherwise.
In a backmount config they also have other uses, however.

Single tank backmount has a significant amount of weight distributed above the hips due to the steel backplate, however if using a stab jacket and a boat load of lead, you will tend to be feet heavy, though this is in the technical diving subforum so twinsets are what it is being compared to. Single tank sidemount with a single AL80 or even twin tank sidemount with al80's are not nearly as prone to being foot heavy as steel tank sidemount setups.

I do not see any sidemount setup as 'prone to being foot heavy'. That's just with poorly positioned tanks.

Inverted doubles are not common enough to warrant discussion, though tend to behave more similar to sidemount in terms of trim

I want to see those. Most I see could be called clumsy but generally move just like any other backmounter.

 

[Bennno]

I do not see any sidemount setup as 'prone to being foot heavy'. That's just with poorly positioned tanks.

Please stop, you have no clue what you're talking about. I've seen several of your youtube videos and many of you're posts on German boards, they clearly show that YOU have no idea how to properly position you tanks. Please stop and take a course, please.

 

[Razorista]

... I've seen several of your youtube videos and many of you're posts on German boards, ...

Watch more! Perhaps you can learn something ;-)

 

[Bennno]

You're not a good diver, you are not willing to learn and you give dangerous advice to people. Noboby can and should learn anything from you. This is why you are banned from every German forum.

I will not further comment in this and I'm sure even beginners recognize that you have not idea what you are talking about.

 

[tbone1004]

I would not start arguing with Bent on that...

You might not feel the difference, but buoyancy and physics don't lie. Jet fins are more negative than slipstreams, with or without spring straps. That is a fact. Even at 1lb per fin, you have a moment arm of minimum 4lbft below the center of gravity. This is not insignificant. If this was insignificant, than all of the sidemount and CCR divers wouldn't have sold their jet fins in favor of OMS Slipstreams, Dive Rite XT's, Mares Avanti Quattros, etc etc.