SMS 50 mod.. would this be retarded?

Finally got to dive the darn thing. I think I like it.

A couple of things, do you think it would be totally retarded to put weight pouches on the cam bands instead of hard weights on the cam bands? I really do not need weights on the first half of a dive, but on the second half they really need them. I'm thinking if I put weight pouches I could add two two lb weights midway through the dive(s)

Also, which D rings do you clip what to? I'm thinking it might be easier to clip the safety clip at the top of the tank to the lower d rings with the side straps and clip the bungee clips to the top D rings...

Not awful, but it's a lot of unnecessary work mid-dive to move weights from on place to another. If you need weight at the end (AL80?) I recommend leaving the weights on them for the whole dive. Also, weight pockets are fine if you don't own your own weights. I recommend leaving the weights on the cambands just because once you get everything positioned how you want it there's no point in moving anything.

Another good option to this (and what I've started migrating towards for Alu tanks) is a sliding d-ring like is done on the Razor/Stealth. Those are BUILT for alu tanks, whereas the SMS50 isn't built on very much sidemount knowledge....so a bit of fiddling is required to get it right. Sliding d-rings (or multiple waist-attachment points) are a great way of dealing with floaty bottoms as you can REALLY fiddle with it until you get it right. With the SMS50's very limited lift, you won't be diving negative steels anyway....so migrating towards an alu-specific setup is something I'd advise.

As for where to clip to, it depends on what your bungee is doing and on where your BCD is sitting relative to your body. The "safety clip" as you're calling it should be on a leash long enough that it doesn't really affect the location of the tank. The bungee should have preference, because where it's clipped influences where the tanks ride. I'd find which ring you like your bungee clipped to and then clip your "safety clip" to another d-ring.

After all the time you have monkey-ing around with your rig and asking about sidemount on internet forums it would be WAY easier to just take a course with a reputable instructor. I know you don't want to but if these guys get a hold of a picture of you in the water they're gonna humiliate the snorkel out of ya.

victorzamora:

Not awful, but it's a lot of unnecessary work mid-dive to move weights from on place to another. If you need weight at the end (AL80?) I recommend leaving the weights on them for the whole dive. Also, weight pockets are fine if you don't own your own weights. I recommend leaving the weights on the cambands just because once you get everything positioned how you want it there's no point in moving anything.

Another good option to this (and what I've started migrating towards for Alu tanks) is a sliding d-ring like is done on the Razor/Stealth. Those are BUILT for alu tanks, whereas the SMS50 isn't built on very much sidemount knowledge....so a bit of fiddling is required to get it right. Sliding d-rings (or multiple waist-attachment points) are a great way of dealing with floaty bottoms as you can REALLY fiddle with it until you get it right. With the SMS50's very limited lift, you won't be diving negative steels anyway....so migrating towards an alu-specific setup is something I'd advise.

As for where to clip to, it depends on what your bungee is doing and on where your BCD is sitting relative to your body. The "safety clip" as you're calling it should be on a leash long enough that it doesn't really affect the location of the tank. The bungee should have preference, because where it's clipped influences where the tanks ride. I'd find which ring you like your bungee clipped to and then clip your "safety clip" to another d-ring.

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victorzamora,

Thanks for your on topic and thoughtful reply.

I wasn't thinking so much "move weights around mid dive" as much as a scenario like this: I do an open water dive where on the first dive I breathe both tanks down to 1750 and on the second dive breathe both tanks down to 500 each with a short surface interval between. On the first dive I leave the weights out of the pouches. On the second dive I pop the weights in. I understand that on one long dive I'd need the weights in the whole time. It's that when I have the weights on during the first dip my bc is inflated to the max and I'm severely overweight.

So, AL80s will have about a 5# weight swing per tank. This means 10# total buoyancy. The SMS50 has 23# of lift. You shouldn't be overweighted. If you are, you need to check your weighting to ensure you're actually neutral with a fully empty bladder at 15ft with empty tanks. If so, there's no reason the SMS50 shouldn't provide plenty of lift. I didn't mention wetsuit compression, but most wetsuits don't compress 13 pounds....and I hope you're not diving a wetsuit like that with the SMS50. The SMS50 was really intended for warm water only, anyway, and is a fairly flawed design in need of some help.

As to placing weights between dives, I personally think that's not a good strategy for success. You shouldn't have to fiddle like that. It's not a BAD idea to do it between dives, it simply shouldn't be necessary. I'm assembling a rig with NO bcd right now for alu dives. Your SMS50 shouldn't be "inflated to the max."

As for what tiki_bill said, I agree wholeheartedly. If you take a good SM course, the VARIOUS threads you started asking very basic SM questions wouldn't have been needed. I'm an Aerospace Engineer with an innate understanding of physics and physical properties, but time with an instructor saved me the frustration, time, and cost that I would have racked up alone. Going to an instructor helped tremendously. I feel like a fairly squared away SM diver, and I'm STILL considering taking an SM class to really reinforce what I know.

Easy solution. Take a sidemount class and don't go into the cave unless you get cave training.

SWAMPY459:

It's that when I have the weights on during the first dip my bc is inflated to the max and I'm severely overweight.

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It makes sense, because that is when you are most negative (full weight of gas, plus weight to compensate for anticipated gas usage and to compensate for exposure protection buoyancy).

That said, if your BCD is fully inflated to deal with two AL cylinders - there's something significantly wrong. In a 3mm wetsuit and 2x Al80s, I can easily make do with a tiny 6lb Trim Pillow for buoyancy.

What rig/buoyancy capacity are you using that needs to be so fully inflated?

What exposure protection are you using (wet/dry, thickness, size)?

What's your calculation on weighting?

First, work out the weighting necessary for you and your rig (no cylinders). One easy method for that is to sink yourself at the end of your long hose (cylinder at the surface), then add/subtract weights until you've got a natural, relaxed horizontal hover with no air in the BCD. It won't be much...

Second, go online and find the buoyancy specifications for the cylinders. Use those numbers to anticipate the extra weight you need to offset cylinder buoyancy at the end of the dive (for AL80 ~3lbs per cylinder).

DevonDiver:

It makes sense, because that is when you are most negative (full weight of gas, plus weight to compensate for anticipated gas usage and to compensate for exposure protection buoyancy).

That said, if your BCD is fully inflated to deal with two AL cylinders - there's something significantly wrong. In a 3mm wetsuit and 2x Al80s, I can easily make do with a tiny 6lb Trim Pillow for buoyancy.

What rig/buoyancy capacity are you using that needs to be so fully inflated?

What exposure protection are you using (wet/dry, thickness, size)?

What's your calculation on weighting?

First, work out the weighting necessary for you and your rig (no cylinders). One easy method for that is to sink yourself at the end of your long hose (cylinder at the surface), then add/subtract weights until you've got a natural, relaxed horizontal hover with no air in the BCD. It won't be much...

Second, go online and find the buoyancy specifications for the cylinders. Use those numbers to anticipate the extra weight you need to offset cylinder buoyancy at the end of the dive (for AL80 ~3lbs per cylinder).

Click to expand...

It's an akona 3mm wetsuit with hood and boots, no gloves.

The BC is a hollis sms 50 with two pounds in each shoulder pocket and two on each side in added weight pockets on the belt (total of 8 lbs of lead)

That had me way over inflated at the beginning so about halfway through I removed the 4 lbs from the belt and it felt great and weighted correctly... until the tanks got floaty and started butterflying.

I wonder if just putting 2 lbs on each tank and no weight in the bc would work?

edit, (I know that with the wetsuit and nothing else, it takes about 6 lbs to get me neutral. That's without the bc)

When your cylinders start getting light then attach them to a more forward sitting D ring on the waist belt, or use a sliding D-ring, solves the issue without the need for weight on the cylinders.