Hollis SMS 100

[Aotus]

And what do need a lower dump for?

The BIG problem is that the butt-plates over the rear of the wing on the SMS rigs end up pushing the air out of the bottom of the wing when heavy steel tanks are attached. You can adjust your tanks and weights to accommodate this, but if you then switch to AL tanks on your waist, it's like you suddenly have a whole extra 6" of wing at the bottom, and unlike the top of the BC, there is no bungee to compress the area and keep the gas even. Using my SMS75, it meant I was suddenly VERY butt-light and it was a real problem getting enough weight low enough to correct for it. Also, with the inflator and dump reversed, the gas had to move all the way from by butt to my shoulder to dump, and that meant going WAY out of trim to dump...

You can dump your wing without a lower dump while staying in trim, that's a FACT!

I'm not making this stuff up Benno. Good for you that you haven't experienced these issues, but that does not invalidate the experience of others. Using AL80s and a wetsuit, I was not able to dump my SMS75 this summer without leaving trim, or reaching behind my back and squeezing the low part of the wing to move air towards the top dump near my shoulder. That is a fact. Using steels (with or without a drysuit) not an issue, using AL80s is a problem.

Razor has the dumps on the side and no lower dump and it's also designed by real SM divers. Cave divers.

I don't know what you have against bottom dump valves, but I think your definition of side dump(on the razor) fits in our definition of bottom dump... that is, it is not at the top like on the SMS100(and SMS75), which is, if you recall, the topic of this thread. Also, it's weird that you're so critical of the stealth, another bottom-dump wing that is, you cannot deny, designed and used by "REAL" sm cave divers, one prolific SM cave explorer specifically, Patrick Widmann.

Back to the point of this thread...We already agree that the SMS BCs are no good for AL80s. My whole position in this thread is that the SMS100 is not ideal because it is limited to functioning well with steels, and not because there is anything special about steels, but because the way they are mounted functionally changes the shape of the wing so that the gas is not allowed to sit in the lumbar region. I argued that the problem with using AL80s is that the pressure on the low part of the wing when using steels(via door handles) is gone, the whole wing is suddenly functional again, and the air is stuck in the low position. Thus, a low dump may resolve that problem. As Andy pointed out, BP/W setups do well with a low dump. Because the triangular shape in the SMS75 wing, and in effect also the SMS100 (from bungees over the top of the wing, top also constricted by CA or other mods), the gas will be over the low back. This is by design for ideal trim, which, you know all about. Tell me then, what is the point of having the dump valve so far from where the gas is intentionally kept? I'll grant you that the ease of tugging at the dump valve when on the chest is comforting, but if so many "real sm" divers with stealths and razors can reach behind them, is there a reason we cannot?

If others CAN use a bottom dump, what is the benefit of top dumps for us? What is the benefit of the SMS BC? I would argue that the most significant benefit of the SMS100 and SMS75 is not for specialization for use with steels - there are "real SM" rigs with bottom dump valves that work fine for steels. Rather, (1)the top-dump of the SMS BCs make it a little easier to reach a dump valve for (hyperactive?) buoyancy tweaking. Also, (2)top-dumps allow for dumping when the diver is head-up, which is not a position that we cave divers are supposed to take, but in FL caves it's not unusual to see a slightly knee-low diver. Together, one could argue, these "benefits" enable and even promote poor buoyancy control and trim, in addition to reducing the efficacy(or at least efficiency) in dumping gas.

The next question for the new SM diver considering the SMS100 or SMS75 is, where should the inflator be? Can I just leave it on the top of the SMS100? The answer depends on your application. In cave diving, we don't want something like the elbow of an inflator hose sticking out behind our head - it isn't protected by the manifold of a double set when you dive sm. So a bottom-mounted inflator still makes sense. It's my opinion that more and more wings are becoming razor-esque or stealth-esque for a reason. This model - bottom dump, bottom inflator, wing volume limited to the lumbar area - WORKS! So, congratulations big innovators Razor and XDEEP, you worked it out, and now you're going to be copied forever with tiny tweaks by everyone else claiming that they've reinvented SM diving.

That's just my position, not gospel. YMMV.

 

[bamafan]

I'm not making this stuff up Benno. Good for you that you haven't experienced these issues, but that does not invalidate the experience of others. Using AL80s and a wetsuit, I was not able to dump my SMS75 this summer without leaving trim, or reaching behind my back and squeezing the low part of the wing to move air towards the top dump near my shoulder. That is a fact. Using steels (with to without a drysuit) not an issue, using AL80s is a problem.


I don't know what you have against bottom dump valves, but I think your definition of side dump(on the razor) fits in our definition of bottom dump... that is, it is not at the top like on the SMS100(and SMS75), which is, if you recall, the topic of this thread. Also, it's weird that you're so critical of the stealth, another bottom-dump wing that is, you cannot deny, designed and used by "REAL" sm cave divers, one prolific SM cave explorer specifically, Patrick Widmann.

Back to the point of this thread...We already agree that the SMS BCs are no good for AL80s. My whole position in this thread is that the SMS100 is not ideal because it is limited to functioning well with steels, and not because there is anything special about steels, but because the way they are mounted functionally changes the shape of the wing so that the gas is not allowed to sit in the lumbar region. I argued that the problem with using AL80s is that the pressure on the low part of the wing when using steels(via door handles) is gone, the whole wing is suddenly functional again, and the air is stuck in the low position. Thus, a low dump may resolve that problem. As Andy pointed out, BP/W setups do well with a low dump. Because the triangular shape in the SMS75 wing, and in effect also the SMS100 (from bungees over the top of the wing, top also constricted by CA or other mods), the gas will be over the low back. This is by design for ideal trim, which, you know all about. Tell me then, what is the point of having the dump valve so far from where the gas is intentionally kept? I'll grant you that the ease of tugging at the dump valve when on the chest is comforting, but if so many "real sm" divers with stealths and razors can reach behind them, is there a reason we cannot?

If others CAN use a bottom dump, what is the benefit of top dumps for us? What is the benefit of the SMS BC? I would argue that the most significant benefit of the SMS100 and SMS75 is not for specialization for use with steels - there are "real SM" rigs with bottom dump valves that work fine for steels. Rather, (1)the top-dump of the SMS BCs make it a little easier to reach a dump valve for (hyperactive?) buoyancy tweaking. Also, (2)top-dumps allow for dumping when the diver is head-up, which is not a position that we cave divers are supposed to take, but in FL caves it's not unusual to see a slightly knee-low diver. Together, one could argue, these "benefits" enable and even promote poor buoyancy control and trim, in addition to reducing the efficacy(or at least efficiency) in dumping gas.

The next question for the new SM diver considering the SMS100 or SMS75 is, where should the inflator be? Can I just leave it on the top of the SMS100? The answer depends on your application. In cave diving, we don't want something like the elbow of an inflator hose sticking out behind our head - it isn't protected by the manifold of a double set when you dive sm. So a bottom-mounted inflator still makes sense. It's my opinion that more and more wings are becoming razor-esque or stealth-esque for a reason. This model - bottom dump, bottom inflator, wing volume limited to the lumbar area - WORKS! So, congratulations big innovators Razor and XDEEP, you worked it out, and now you're going to be copied forever with tiny tweaks by everyone else claiming that they've reinvented SM diving.

That's just my position, not gospel. YMMV.

I agree with most of this except I do like a top dump for backmounted stages. With Aluminum tanks I front mount my stages because it is easier and with the light aluminum tanks I can still reach my scooter d ring. This is not true with heavy steel tanks and front mounted stages. One thing that wasn't mentioned about the SMS's is with the door handles mounted on top of the wing as you inflate the wing the tanks at some point rise. With heavy steel tanks this is your center of gravity and the tanks will tend to be level thus forcing your hips down. I had this issue and was horrified when I saw myself on video. YouTube and Facebook are full of examples of this as it cause people to drop their knees.

 

[DevonDiver]

Even Hollis' new SM wing, the Katana, is now following the English/Mexican Cave design tradition. It's a major step forward for Hollis... and it's been getting very positive reviews thus far.

I'm seeing a recent trend with American SM manufacturers to acknowledge the needs of aluminium cylinder divers (a larger market share globally).

The latest rigs from companies like Hollis and DiveRite are better suited to cope with both steel and aluminium tanks... and also emulate designs that are more modular and lightweight for travelling and warm water diving.

SMS100 was flawed from the outset for many sidemount needs. In fairness, it was several design 'generations' ago... and it was pretty innovative when first released. Even for drysuit / steel cylinder diving.... serious users were sending their SMS100 to Edd Sorensen for his modification package. Those mods, in turn, influenced design of the Halcyon Contour and, later, the SMS75.

The XDeep Stealth Tec shows design evolution in the opposite direction - the English/Mexican Cave heritage adapting for increased lift requirements, suiting both high-level tech/overhead and steel cylinder divers... Whilst simultaneously solving the 'turtleshell' issue that had plagued high buoyancy warm water rigs previously.

 

[Bennno]

what is the point of having the dump valve so far from where the gas is intentionally kept?

Doesn't matter where most of the gas is kept, it'll move up through the dump either way. The SMS75/Edd mod is special case due to the way the wing behaves when you use it with AL. My rig doesn't do that and the other rigs don't do it either. The SMS75 let's the buttom of the wing unfold upwards there are no steels weighing down the BP, as you have already noted... that's way the SMSs suck for diving with ALs.

If others CAN use a bottom dump, what is the benefit of top dumps for us?

As I already mentioned. When you're in a dry suit you have to move to dump the wing and the suit. The guys that tell you how great the valve position is are mostly warm water divers, IMHO. The Stealth guys put the dump where it is because there is no other place to put it.

So, congratulations big innovators Razor and XDEEP, you worked it out, and now you're going to be copied forever with tiny tweaks by everyone else claiming that they've reinvented SM diving.

If the Stealth is NOT a Razor copy, the Stealth's release date is one hell of an coincident... and so is the z-system and a whole bunch of other systems. The weight system is better for sure, but IMHO Steve is the one who did the innovation, he had a fresh take on the old-school UK harness... he also did youtube marketing very well and kind of innovated that (that's not a knock).
I can tell you why the Razor is copied so much. It's dirt cheap to make! Ridiculously cheap to make, especially the systems that don't have any metal parts like the Razor and you make it in a low wage country like xdeep does it in Poland. A Razor-Style wing requires very little sewing which is a major cost factor when making bcds. Look a rigs like the Armadillo, it probably costs twice as much to make (if not more), but sells for pretty much the same retail price.

 

[Bennno]

In fairness, it was several design 'generations' ago... and it was pretty innovative when first released.

Huh? Didn't Hollis just rip-off of the Recon? It's almost a carbon copy.

Whilst simultaneously solving the 'turtleshell' issue that had plagued high buoyancy warm water rigs previously.

I have not seen a Razor-type rig that doesn't get bulky when it actually has to carry some gas.

 

[Aotus]

If the Stealth is NOT a Razor copy, the Stealth's release date is one hell of an coincident... and so is the z-system and a whole bunch of other systems. The weight system is better for sure, but IMHO Steve is the one who did the innovation, he had a fresh take on the old-school UK harness... he also did youtube marketing very well and kind of innovated that (that's not a knock).
I can tell you why the Razor is copied so much. It's dirt cheap to make! Ridiculously cheap to make, especially the systems that don't have any metal parts like the Razor and you make it in a low wage country like xdeep does it in Poland. A Razor-Style wing requires very little sewing which is a major cost factor when making bcds. Look a rigs like the Armadillo, it probably costs twice as much to make (if not more), but sells for pretty much the same retail price.

I agree that the razor was the biggest innovation, or so is my understanding based on my shabby knowledge of the long and interesting history of SM. I think the stealth 2.0 classic was different in enough ways to think it a new innovation, for better or worse. I don't want to list features, but isolating lift to the lumbar region was a good move that most other big brand rigs still don't quite commit to. The new tec/rec versions do this too, but the covering over the bladder itself makes it look more like a razor or diamond (or katana) in shape, for streamlining, without losing the advantage of keeping all the gas around the lumbar and close to the dump valve. That is, again, my understanding. I have a stealth tec, but have little experience with it yet.

 

[Aotus]

I agree with most of this except I do like a top dump for backmounted stages. With Aluminum tanks I front mount my stages because it is easier and with the light aluminum tanks I can still reach my scooter d ring. This is not true with heavy steel tanks and front mounted stages. One thing that wasn't mentioned about the SMS's is with the door handles mounted on top of the wing as you inflate the wing the tanks at some point rise. With heavy steel tanks this is your center of gravity and the tanks will tend to be level thus forcing your hips down. I had this issue and was horrified when I saw myself on video. YouTube and Facebook are full of examples of this as it cause people to drop their knees.

Good points. I somehow forgot about the top mount stages issue, and I haven't tried it myself. That Michur guy has great videos showing an absurd number of tanks that we can swim round with and still use the bottom dump of this stealth classic.

I didn't even think of the knees-down issue you described! I am on the buoyant side (adapted to diving, lot's of extra "bioprene"), so I'm not sure I have ever filled my sms75 enough to get that effect.

 

[Bennno]

... but isolating lift to the lumbar region was a good move that most other big brand rigs still don't quite commit to.

I don't think it's good. That's one of the reasons I don't like the stealth rigs. When you breath down your tanks and you're in a dry suit you WANT some lift further up, otherwise you'll be top-heavy.
This is also a warm water thing, in a wet suit you're tend to be more foot-heavy anyways so it doesn't really matter.

... without losing the advantage of keeping all the gas around the lumbar and close to the dump valve.

Why do you see this as an advantage? The gas move up and out either way. The Hollis rigs are kind of odd, other rigs don't behave like they do.

 

[DevonDiver]

Drysuit... trim.... dumping

 

[DevonDiver]

I have not seen a Razor-type rig that doesn't get bulky when it actually has to carry some gas.

That's the nature of English / Mexican Cave style rigs using triangle/rectangle /diamond shape wings.

There's a few rigs that use baffles inside the wing, which prevents turtleshell, but limits max buoyancy.

I do like the Stealth Tec because it provides sufficient lift for most tech purposes but doesn't billow much at all.