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Wreck Diving on Sidemount or Backmount Doubles

Discussion in 'Wreck Diving' started by cklaus, Sep 6, 2020.

  1. ToneNQ

    ToneNQ ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Australia
    BM is much easier to penetrate the narrow doorways, passages and hatches in wrecks. To use SM you spend a lot of time rolling sideways, it works but its suboptimal. Side mount is for low passages, ie caves, but its also very comfortable for solo diving and very flexible because its single tanks. But for wreck diving, if it's an option, I much prefer a BM twin set. Much quicker to gear up on the boat and much easier to manoeuvre inside the wreck.

    There's some good youtube videos of SM courses on the Gozo wrecks. Those dives are 23°C at wreck depth (under the thermocline) and 35-40m in depth. The spend a bit of time either rolled over, or unclipping a tank to push it forwards. With BM those wrecks are easy, straight through. Most of the engine rooms would be too tight in SM.
    divad, NothingClever and Dark Wolf like this.
  2. grantctobin

    grantctobin ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Chicago
    Unfort divemaster doesn’t mean anything in terms of overhead environment or technical training. I’d argue that on average it’s a net negative. Poo on SDI for allowing limited penetration at the recreational level with a single tank. Unequivocally f that.

    Let’s assume that you’re in a drysuit and drygloves with a large amount of undergarments to loft (as you really must be in this area to do any extended range diving). Let’s also assume the local levels of sidemount training and backmount training available to you are on par with one another (they’re not).

    In doubles, gearing up is as clean as sitting on the bench, necklacing your reg, connecting your suitgas, and routing your long hose. Stand up, fit through the gate, and jump off the boat. Deco bottles either tied to a down line or clipped onto you either by yourself or by crew depending on your strength level. Either way, the deco bottles are not really part of the ballast equation and at most, are ~5lb negative (50%/70’ AL80 bottle) so clipping them onto yourself at 10’ or 20’ is of no concern if they’re on a downline. There’s never a point when you’re in the water when all of your ballast is not on you. The general choice in the area are HP100s/LP85s (less so bc the Midwest doesn’t really cave fill), HP119s/LP95s. This helps alleviate the need of a massive amount of weight stored somewhere. While I think AL80 doubles are great wetsuit tanks, they’re not my top choice in a drysuit.

    In sidemount, there’s three ish ways to get your bottles to you. Having them passed to you from someone on the boat, a downline, or by clipping them onto your harness while on the boat. Option 1 is pretty reckless and even worse with steel cylinders, so we’ll skip that. Option 2 involves one cylinder being clipped on while on the boat and one on a down line. Doable in aluminum cylinders, more difficult or reckless with steel cylinders. Now you need to add whatever portion of your ballast the down line cylinder accounted for onto your harness and are overweighted. Clipping bottles off with drygloves underwater is a pain depending on the harness/glove/attachment point/boltsnap combination and if you accidentally drop one, it’s gone. Connecting a wing inflator across your chest in dry gloves with 1-2 pairs of liners is difficult at best and a fools errand at worst.

    Which brings us to option 3, or attaching your SM cylinders while on the boat. You’ll likely need to add leashes to the top of your cylinders to avoid stretching the bungee. So now, to get geared in, you need to put your harness on (with light can, whatever necessary weight, suit gas, suit heater...and finding a place for all of that). Clip in one bottle top and bottom, connect the bungee, run the necklaced reg around your neck, connect your wing. Then, now 50% wider than you were prior, you need to do the same on the other side. Cool taken care of. Sweet, you’ve done your modified S drill, gas is on, and you’re ready to stand up. Except now you’re taking up twice the bench width of your compatriots. If you’re out of Hammond and diving the Hume, it’s nbd if the boat isn’t full. Full boat or one of the corner seats, you’re either in the way of other divers or the last off the boat because of the amount of help and space you need. The Alma out of MKE has more space on the bench but it’s difficult to sit down effectively to put your fins on with sidemount cylinders clipped on in general. Now, you just have to jump off. Ouch, the forward gates on the Seaquest aren’t wide enough to do a giant stride safely so you need to fall in half sideways. The rear isn’t that much wider. Same story with the gate on the Molly V or the Alma, though iirc the Alma is slightly wider and might work if you’re naturally narrow and with 7” cylinders. Can’t easily clip on SM deco bottles hunched over (because you’re main bottles are already on and you can’t sit straight) and being hinged over with your primary bottles on covers where those deco bottles should be getting clipped.

    Sweet, now you’re in the water and diving. All is well. Wait, is the wreck upright? Hallways work better in backmount if they are. But now you’re in sidemount and swimming canted. Admittedly nbd if the wreck is on its side. Dive comes to an end. Ah poo now you need to get out. Did you unclip your leashes in water and now need to reclip them? (hint leave them clipped). Are your deco bottles as cleanly doffed underwater as they are in backmount? No, not if they’re laying where they should be. It’s even more difficult when you have a 70-100mm dry glove ring in your way. Storm rolled in and now you’ve got 3’+waves and you’re less balanced and trying to fit in a smaller pocket/gate relative to your girth than your backmount friends. Smack goes the SM cylinder against the gate or the ladder or the rack. Wait I thought sidemount was supposed to make maneuvering on the surface easier? Once the process of getting you in a seat is finished, most people seem to need help unclipping themselves from their gear.

    Cold water sidemount is a burden on the crew, your body, and the boat. There’s a small number of people that manage it, but for most it’s a pis poor idea. Learn SM when you actually need it and tip real well on those boats if you don’t need it but think it’s cool.
    SavDiver, LiteWeight, divad and 6 others like this.
  3. DiveTucson

    DiveTucson Dive Shop

    This! SM is a tool for a specific job and boat diving in the Great Lakes or Open Ocean wrecking it is almost never the right tool!

    To many “lifestyle” SM divers.
  4. cklaus

    cklaus Registered

    # of Dives: 200 - 499
    Location: Chicago, IL
    Thank you grantctobin. That was an full and understandable answer which helps me see the value of BM over SM. I know there are good reasons the techs are diving BM and it seems like you've listed many.

    We agree about DM. I don't like listing my "qualifications" as all too often certs/training/qualifications don't make a good diver.

    I know I have far more to learn before I consider myself a true wreck diver. As I continue my training, I hope to meet you on a boat and earn your respect.

    grantctobin likes this.
  5. cklaus

    cklaus Registered

    # of Dives: 200 - 499
    Location: Chicago, IL
    Thank you for your answer and YouTube suggestion. This info is very helpful in my deciding which direction I want to head.

  6. NothingClever

    NothingClever ScubaBoard Sponsor ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: Red Sea and Atlantic Ocean
    I’d characterize nearly all of the realm of SCUBA diving as a lifestyle.
    lsmike, Paul M, shoredivr and 3 others like this.
  7. Diving Dubai

    Diving Dubai Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: Dubai UAE
    I’m going to fundamentally disagree with @grantctobin and say that I think he’s overstated the negatives of using SM

    However, it is a fact that a lot of SM divers are ill prepared and, their rig is ill conceived for oat diving, meaning that they do become a burden

    I’m more than happy to dive SM in OW off boats, from all sizes - Ribs upwards

    My group is very intolerant of divers that faff gearing up, because for a large proportion of the year, the surface air temp is +105F. While underwater it’s going to be the low 70’s. People (me included) get hot and grumpy real fast!

    So for me I adopted Ring bungees and my tanks are clipped on and off on the boat. Inside wrecks, SM and BM both have their strengths and weaknesses, and if we’re going down that route then we should claim RB are not suitable for wrecks, which is clearly nonsense

    ONe needs to look at the big picture. By that I mean the overall logistics, from loading your car with kit, then day before, to unloading it when you get back home. There are so many permutations that it’s impossible to say BM/SM is better. Realistically you go with a the system which has the least amount of downsides

    The absolute most important point especially with SM is to adapt and configure your kit so that it meets the demands of your chosen diving environment, and whether your SM, BM doubles of BM single with pony, Make sure you can handle your kit without needing assistance (that’s not to say if offered you shouldn’t accept help, just you need to be self sufficient for those times when you have to be)

    Having tried both, it was an easy decision for me to use SM over BM doubles, others may think differently and that’s fine

    But to say categorically that SM off a boat in OW wrecks is bad, is plain wrong
    Cdncoldwater, lsmike, Paul M and 6 others like this.
  8. grantctobin

    grantctobin ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Chicago
    Are you in drygloves w 400g undergarments?

    Unrelated and debatable, choker systems (DR ring bungee system) categorically suck, esp for AL cylinders.
    rjack321 likes this.
  9. Jim Lapenta

    Jim Lapenta Dive Shop

    # of Dives: 500 - 999
    Location: Canonsburg, Pa
    I dive SM off of boats in a drysuit, 5mm gloves, hood, etc with an additional 40 stage. I don't have any issues but then, I see a fair number of people who do. Usually, those who received poor training or learned on their own. I am totally self-sufficient in gearing up but will also gladly accept help, if offered with fins, handing me my stage or right cylinder, etc., but don't need it.
    I see others who are a hot mess, to say the least. They can't get their cylinders clipped or bungees hooked in without help. They take up a lot of room and time. I don't hurry to get geared up but try to be as efficient and well thought out as possible. I'm often ready to go sooner than some in BM doubles.
    That said, there are times when it makes more sense to just dive BM. I have gone on day trips where there was 18 people on the boat. Crowded but still manageable. But the depths were only to 100-120 ft. I didn't need sidemount for that. Mix of rec and tech divers with plans for little to no deco. So an LP119 filled to 3200 PSI and a 40 of 50% was all I needed for each dive. I still had 140+ cu ft of gas which was plenty for that dive with a few minutes of deco. Actually 25 min bottom time with 15 min of deco and enough gas for the second dive with a similar profile.
    After diving SM pretty much exclusively for months, it felt like having nothing on and was quite enjoyable.
    There are also some boats that don't like to see SM divers and a few who actually discourage people from using it.
    Other boats offer challenges with ladders, Fin on Christmas tree types are easy and the most friendly if the walkway at the top is wider. Narrower ones may require you to turn sideways but they still work. Other ladders that require fins off may be narrow enough that to safely navigate them you need to doff and hand up one cylinder. Some boats are cool with that, others not so much.
    Best to ask ahead and be honest about your level of experience and whether or not you'll need help.

    On a side note. Whether or not SDI permits limited penetration is irrelevant. They do as an option with line use as an option BUT any decent wreck class is going to require the use of a line for any penetration as part of the class. I'm an SDI wreck instructor and TDI Adv Wreck Instructor. My SDI wreck class is 6 dives vs the minimum of 3. Limited penetration only occurs on the last 2 with lines. The first 4 dives are all outside with heavy emphasis on why recreational wreck divers have no business penetrating a wreck without overhead training. Dive 4 is all about line use. Dives 5 and 6 are in the light zone penetration with a line using multiple tie-offs. These are after covering in class the number of ways you can die in an overhead as short as two body lengths if you don't know what you are doing.

    Just because an agency says you can do it, doesn't mean you should. I've seen people I would refuse to do the full recreational wreck class with unless they had a serious change in attitude. Outside only for them.
    Cdncoldwater, lsmike, JBFG and 4 others like this.
  10. Diving Dubai

    Diving Dubai Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: Dubai UAE
    No, of course not. In the summer the Air temps can be at 120F, top 20m 96F, and 75 below that. We have our own challenges. If I were wearing thick gloves then my kit will be configured with snaps that I can manipulate.

    This really isn’t that difficult..

    That’s a debate for sure. I switch between steel 12l and Al 80 depending, and test I have a version of ring bungees

    My system has been tweaked by guys who’ve go a few 1000 dives rigged like this, so their critical eye and minor tweaks to optimise the rig was invaluable.

    Now you may not agree, and that’s fine. My rig has been designed so that I can enter th water with both tanks and a dpv, and climb out quickly (after handing off the dpv)

    You’d probably really freak to find out my (non penetration slings) have accessory pockets on the cam bands again perfectly optimised for my environment - which is generally jumping into insane (to some) current’s.. no down lines, no time for mincing at the surface attaching bungees

    Hence my comment above, that the primary concern is to adopt a rig that matches your environment and is configured as such, rather than generalising that only one type of rig is suitable. There is NO one size size fits all
    lsmike, jdeblese, shoredivr and 5 others like this.

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