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Sidemount or Backmount?

Discussion in 'Cave Diving' started by Tickler, Dec 12, 2013.

  1. Tickler

    Tickler Solo Diver

    # of Dives: 500 - 999
    Location: Florida
    I Have been cavern certified for a while not and am soon going to be moving forward with my certification. The next steps as I am sure you all know requires complete redundancy including 2 first stages. I think that instead of investing in H-valves on all of my tanks, I want to go ahead and jump to having 2 tanks. I am wanted to hear other troglodytes opinions on the pros and cons of diving 2 tanks sidemount vs. diving backmount doubles. What sort of set up would you recommend? The shop nearest me does have a killer deal on the Hollis sms100 but do you think I should stick with a BP/W set up or does it matter?

    Thanks for your help.
  2. Doppler

    Doppler Dive Equipment Manufacturer

    I declare a conflict of interest... see my signature! LOL

    BUT the one thing I wanna point out Chris... try out an SMS75 from Hollis before you invest in the larger SMS100. Unless you are gonna dive with scooters, multiple stages etc. the 75 will be a better fit for your needs.
    Coztick likes this.
  3. tomfcrist

    tomfcrist NAUI Instructor

    # of Dives: I'm a Fish!
    Location: Virginia, USA
    I think you will find back mount easier to learn out of the gate, but side mount isn't difficult to master with a good instructor. Side mount is really beneficial when diving low overhead but wide restrictions, where back mount is slightly better in high relief passages and wrecks. Whichever direction you go, best of luck to you, and find a good cave instructor.
  4. Tickler

    Tickler Solo Diver

    # of Dives: 500 - 999
    Location: Florida
    I can get the sms100 for the same amount it would cost me to order in a 75- should I still go with the 75 or get the 100 and have some room to grow into it as I gain experience?
  5. Doppler

    Doppler Dive Equipment Manufacturer


    In truth, Chris, it's difficult to access correctly without seeing you and seeing you in the water. You should speak with your instructor. There are several great ones... many who teach cave in both BM and SM. Listen to what they tell you because there are pros and cons to each. After more than 20 years cave diving in BM, I only teach SM now so I am naturally biased :)

    However, I honestly feel that the modifications made to the SMS75 design translate into a better all-round system out of the box than most anything else.
  6. Tickler

    Tickler Solo Diver

    # of Dives: 500 - 999
    Location: Florida
    Why did you switch from BM to SM? What about it do you like more?
  7. TSandM

    TSandM Missed and loved by many. Rest in Peace ScubaBoard Supporter

    I am a backmount diver who has taken an OW sidemount course. Here's my take: The vast majority of the cave that is out there to dive, and ALL the cave anyone should be doing as a novice cave diver, is accessible in either configuration.

    If you already own a backplate setup which is properly adjusted for you, going to doubles is a matter of buying a wing (say $300) and slapping on a set of doubles. You will have to spend some time learning how to distribute your weights and manage your posture to trim out in the doubles.

    You will have to spend time adjusting and weighting a sidemount setup, and also figuring out how to arrange the hardware on the tanks, to trim that out.

    Walking in backmounted doubles is annoying, but walking in sidemounted tanks is no better. Sidemounted tanks can be taken to the water one by one, but if you are going up and down three flights of stairs to do it, I have personally found one trip with the doubles is actually easier.

    Sidemount is currently wildly popular. It's fun -- when you get the tanks settled properly, you're extremely stable in the water. But it's a bigger hassle to set up and get into, and doesn't offer as many convenience advantages as I thought it would before I tried it. And by the time you NEED sidemount, you will be a number of classes and probably a lot of gear down the cave diving road. :)
    SanDiegoSidemount and Doppler like this.
  8. Glenn08

    Glenn08 Contributor

    How much air do you need ? Do you want an isolation valve between the twin tanks ? I use twin 50's mounted valves-down with a Selpak manifold. I wanted two independent regulators, but not an isolation valve. I can access all of my air from either regulator. My 72's were to long to wear valves-down comfortably.
  9. Doppler

    Doppler Dive Equipment Manufacturer

    My very first adventure in a cave (as a kid in England) was "sidemount." VERY different to what I dive and teach now... BUT

    My major issue was what SM guru Lamar Hires at DiveRite calls a "lifestyle choice." I switched because after 20-odd years wearing and teaching in what was often a pair of honking great big double 16 litre steel tanks (coupled with horrible posture when sitting at a desk writing... just threw my shoulders back) my T3 vertebra is... what's the polite term... compromised. My doc gave me a simple choice and the obvious solution was to move away from BM.

    What Lynne mentioned above is all very germane which is why I suggested speaking with a cave instructor that teaches both. That's the best way to get an unbiased view in my opinion. (I do not subscribe to Lynne's suggestion that "by the time you NEED sidemount, you will be a number of classes and probably a lot of gear down the cave diving road." I know of several folks who moved from a single cylinder to SM without ever putting on a set of twins. However, they have had good instruction and take direction well.)

    Whichever way you decide to go, cave diving is wonderful. ENJOY
    Johanan, Randy g and Tickler like this.
  10. theskull

    theskull Divemaster

    # of Dives: 2,500 - 4,999
    Location: St. Louis, MO
    Doppler made the most important points, as he always does. After years of diving BM doubles I chose to learn Sidemount because we had students who wanted me to teach it. After a dozen dives I was hooked, and sold off all my BM gear.

    Another related fact: Backmount doubles will require committing to a number of expensive gear choices that will be hard to sell later when you move to Sidemount--a few sets of manifolded banded tanks, bigger wing, V-weights, etc.
    Going directly to Sidemount only requires a new harness, another reg, and buying or borrowing any tanks you can get hold of-as long a any 2 of them are pretty well matched to each other in size and weight.

    In my area, about half of the BM divers have switched to Sidemount, and noone starts down the BM path anymore--learning Sidemount from the start is just easier, less expensive, and more natural. Plus, you never have to do the dreaded behind-the-head valve drill!

    Coztick, Johanan, Randy g and 3 others like this.

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