Problems on Hollis sms 75 for Alu Cylinders? Just back from a sidemount class...

[stanleychan]

I have taken a sidemount course last weekend. My instructor was once trained by Edd using Hollis sms 100. However, he used SS cylinders all along his instructor training period so he didn't have much experience in divng an sms 100 style sidemount BC with Alu cylinders. He uses razor when diving in warm water with Alu cylinders all the time.

So even though I finised this course I still can't find a proper way to attach the Alu cylinders to my sms 75. When I attach the bottom bolt snap to the rail on the soft pad, the cylinders will fly up nearly 90°. That was very terrible.

I referred to the user's manual of hollis sms 75 and found that the diver in the demo picture of "final configuration" doesn't use the rail on the soft pack. It is very streamlined. However, I couldn't see the details of how he attach the cylindes. So, it will be appreciated that anyone could show me your configuration.

And when diving with Alu cylinders and wetsuit, it will cause a head down trim if you put two leads on your shoulder. So I would also like to know how you arrange your lead position and attachment method.

Looking forward to your suggestions....​

 

[FiddlerOnTheRoof]

Anytime I use AL80's on my SMS75 I put 3pd weights on the tanks and still use the door handles or rails. You can also attach D rings on your waist line and attach the AL80s there. Seems to work for some people.

 

[rongoodman]

How about the thick rubber rings on the waist belt that the Stealth 2 uses? Instead of having to move the tank to a more medial D-ring as the butt lightens, you slide the ring forward on the webbing.

 

[Patoux01]

Next time, find an instructor that is interested in getting things to work
Add a d-ring on the waist strap, ideally a sliding ring (just like the stealth), or 2 d-rings. Clip the tanks there, when they get tail floaty, clip to the front or push the ring forward. Nice and easy.
For the stage/deco, that one could be clipped to the buttplate I guess, except if there's another attachment point closer to your body (under the buttplate? I only know so much of the sms75)

I wouldn't put weights on a tank, they're heavy enough out of the water to handle.

 

[FiddlerOnTheRoof]

Next time, find an instructor that is interested in getting things to work
Add a d-ring on the waist strap, ideally a sliding ring (just like the stealth), or 2 d-rings. Clip the tanks there, when they get tail floaty, clip to the front or push the ring forward. Nice and easy.
For the stage/deco, that one could be clipped to the buttplate I guess, except if there's another attachment point closer to your body (under the buttplate? I only know so much of the sms75)

I wouldn't put weights on a tank, they're heavy enough out of the water to handle.

Putting weights on the tanks is a very common practice here in the US, not so much in Europe. Sliding D rings in my opinion would be the best way to go. I prefer my steel 100's with the SMS75. The weights on the tanks for me is just a quick solution when I travel.

Also the best thing I ever got for the SMS75 was the weight back mounted attachment...

 

[stanleychan]

I've thought about putting weights on the Alu cylinders, but it might let your feet down.

In addition, when diving with wetsuit, I just need 1.5 - 2kg weight. So, even if you put 1kg on each cylinder, they could still float up as the gas in it become less.

Sliding ring is a good choice, plan to buy one.

 

[Sidemount_Stu]

Out of interest if you're diving mainly Ali tanks, what made you go for an SMS75? I'm not suggesting it's a bad rig, but it's really designed for steel cylinders in it's primary use, hence the rails.

If diving Ali's all the time, i'd have gone for something like the stealth, Diamond, Razor etc.....

As others have already said, sliding D ring is a good option, or failing that, 2 x D ring on each side of the waist, 1 positioned as normal, roughly in line with the hip/arm pit line and the other further forward. Start the dive on the rear most D rings and as the butts get floaty, move the boltsnap to the forward D ring.

 

[stanleychan]

Out of interest if you're diving mainly Ali tanks, what made you go for an SMS75? I'm not suggesting it's a bad rig, but it's really designed for steel cylinders in it's primary use, hence the rails.


If diving Ali's all the time, i'd have gone for something like the stealth, Diamond, Razor etc.....

As others have already said, sliding D ring is a good option, or failing that, 2 x D ring on each side of the waist, 1 positioned as normal, roughly in line with the hip/arm pit line and the other further forward. Start the dive on the rear most D rings and as the butts get floaty, move the boltsnap to the forward D ring.

Thanks for you advice
That I come to hollis sms 75 is because my diving environmnt in China. If I dive in my country, most of the dive sites being fresh cold water from 4℃ to 16℃, and the cave system in Guangxi province is of karst land feature with low temprature and strong currents (to advance to a cave diver is on my schedule). So there are possibilities to use drysuit and steel cylinders.

And when I do fundive in warm southeast Asian countries, though being better to use razor/stealth, there are some circumstances not suitable for sidemount, I have to use single tank backmount. So I think the multi-use hollis sms 75 is a compromise for various needs. Yes, sms 75 is a bulcky BC. But I don't want to take both a sm bc and a BP/W along my journey.



---------- Post added April 15th, 2015 at 04:07 PM ----------

I found a sliding ring called "LB-Sliding Ring" but didn't know where to buy. Does anyone knows? or recommend some alternates? :blinking:

 

[Patoux01]

I'm not aware of any dealer in your part of the world, there's one in France, there's obviously Santiago Pintado in mexico, Steve Martin sometimes has a few (UK / malta).
They'd be very expensive for you imo.

Alternate: a simple sliding tri-glide, they exist for boating, however not all D-rings do a nice job on them is seems... haven't tried them.

 

[DBF]

These are the two types of weight systems we have made for the sms75. To get the weight further back

The first is for single back mount and sidemount with out the need to remove it. It bolts into the twin tank mounts. Sit outside of a 12lt faber tank. But it is bulky.

The second has lead roofing sheet sandwiched between checker plate and rubber. Same weight as first but 12mm high. For sidemount only, uses the same mounts


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